Structural change in the international horticultural ...

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Scientia Horticulturae 125 (2010) 1–15

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Review

Structural change in the international horticultural industry: Some implications for plant health Katharina Dehnen-Schmutz a , Ottmar Holdenrieder b , Mike J. Jeger c , Marco Pautasso c,∗ a

Warwick HRI, University of Warwick, Wellesbourne, Warwick, CV35 9EF, UK Forest Pathology & Dendrology, Institute of Integrative Biology, Department of Environmental Sciences, ETH Zurich, 8092 Zurich, Switzerland c Division of Biology, Imperial College London, Silwood Park, Ascot, SL5 7PY, UK b

a r t i c l e

i n f o

Article history: Received 28 August 2009 Received in revised form 19 February 2010 Accepted 25 February 2010 Keywords: Agriculture Cut ﬂowers Globalization Greenhouses Invasion biology Network theory Ornamentals Phytosanitary regulation

a b s t r a c t The horticultural sector has seen much structural change both nationally and internationally over the last decades, but the implications for plant health have been neglected. We review in the context of the risk of emerging plant diseases recent developments including the movement towards a global horticultural market, the rise of the horticultural industry of many developing countries, and the economic integration of the European Union. North America is typically well ahead of other regions in economic developments, and in horticulture this is shown for example by the growing importance of Mexican growers. Asia is rapidly catching up also in horticulture, with China and India becoming key producers. Australia and New Zealand show the impact of change in horticulture extension services. The Eastern enlargement of the EU is having profound inﬂuences on fruit and vegetable growers both in the new and in the old member countries. Similar developments are taking place in South America and Africa. In all continents, there is a general trend towards fewer and larger horticultural growers, an increasing role of supermarkets and a concentration of the retail pathways. These developments have consequences for the control of plant pathogens and invasive species. Technical issues seem to be of lesser consequence in terms of structural change compared with labour and trade aspects. However, examples can be found where technical innovations have opened up new opportunities or provided solutions to pressing problems, as can be seen in the hardy nursery stock and ornamental industry in the UK. Future technical, economic and social impacts on the sector are likely to play a key role for securing a diverse and reliable food supply for the still expanding world’s population. Recent advances in modelling disease spread in complex networks representing trade pathways should be used to target control of introductions of new plant pathogens. There is a need for more long-term research on how structural change in the horticultural sector will affect and be affected by climate change. © 2010 Elsevier B.V. All rights reserved.

Contents 1. 2.

3. 4.

A global horticultural expansion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Horticultural trends in individual countries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2.1. The Americas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2.2. Africa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.3. Asia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.4. Australia and New Zealand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.5. Europe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.6. The UK hardy nursery stock industry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Implications for plant health . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Challenges for future plant health . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

1. A global horticultural expansion ∗ Corresponding author. Tel.: +44 020 75942533. E-mail address: [email protected] (M. Pautasso). 0304-4238/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.scienta.2010.02.017

The increase of the global human population of the last decades has been accompanied by a rapid rise in horticultural crop pro-

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duction (vegetables, fruits, wine, etc.), including the production of ornamental plants and ﬂowers (Menini, 1987; Lawson, 1996; Harrison, 2003; Janick, 2007; Hoffmann, 2009). This phenomenon has been made possible by the increased adoption of free market policies and trade agreements, which have reduced trade barriers to plant shipments among different countries of the world, although hurdles in the horticultural trade are in many cases still substantial (Rae, 2004). At the same time, the global horticultural expansion has been enabled by continuous product improvement. This, in turn, was a consequence of advances in breeding and tissue culture propagation, which have brought lower real product costs and year-round availability. The latter has led to a rapid expansion of horticultural capacities in countries able to supply products during the winter months in the Northern hemisphere. The global horticultural and ﬂoricultural expansion has thus been beneﬁcial to many emerging economies, although many challenges still persist (De Groot, 1999; Norman, 2003; Humphrey, 2006). Developing countries are indeed generally trying to develop horticulture industries to increase export revenues and to beneﬁt rural communities (Warrington, 2005; Lumpkin, 2007). Technical innovations in greenhouse horticulture (e.g. soil-less production; Jiang and Yu, 2007) are likely to be essential to maintain sustainability of food production in the face of the predicted widespread water shortages (Elomaa et al., 2008; Van Kooten et al., 2008). In spite of the many developments in the horticultural production of most countries of the world, there has been insufﬁcient attention to how such international structural change can affect the risk of spreading invasive plants, diseases and pests (McRae and Wilson, 2002; Brasier, 2008; Evans and Waller, 2010; Hulme, 2009; Drew et al., in press). There have been attempts to improve plant inspection policies at countries’ borders using probabilistic models (Surkov et al., 2007, 2008a,b, 2009; Mwebaze et al., 2010), but such commendable approaches need to be complemented by modelling how structural change in the importance of producers, wholesalers and retailers in the international trade pathways affects the likelihood of plant epidemics occurring. Moreover, much literature is appearing documenting rapid developments in the horticultural and ornamental industry of many countries and this still needs to be summarized in the context of plant health. In this review, we summarize selected literature on recent horticultural developments including the emergence of an international horticultural market, the relatively rapid growth of the horticultural industry of many developing countries, and the consequences for this sector of the increasing economic integration of countries belonging to or aspiring to membership of the European Union. We focus on horticulture but include examples from ﬂoriculture, the production of ornamentals, or agriculture in general wherever relevant for the issues considered. Whenever possible, we point out consequences of these structural changes for the likelihood of introduction of new plant pathogens and other invasive species. We point out horticultural trends in (i) the Americas, (ii) Africa, (iii), Asia, (iv) Australasia, (v) as well as in European countries. As an example where there has been both structural change and threats from new plant pathogens, we summarize economic and technical developments of the UK hardy nursery sector. Some implications for plant health, research needs and likely future challenges are then discussed. 2. Horticultural trends in individual countries 2.1. The Americas The horticultural industry in North America is one of the most dynamic of the world. It is thus often a precursor of structural changes which propagate to other countries with a more or less

prolonged delay. Consolidation and structural changes have long affected the North American ﬂoricultural market (Haines, 1998). This development has been further spurred by several free trade agreements between Canada, the USA and Mexico (Dempster, 1989; Meilke and Van Duren, 1996; Furtan and Van Melle, 2004; Olper and Raimondi, 2008). The large-scale movement of horticultural products and ornamental plants within and from/to outside the North American continent has certainly increased the likelihood of transferring unwanted species (Bandyopadhyay and Frederiksen, 1999; Timmons, 2005; Gullino and Garibaldi, 2007; Gamliel, 2008). New horticultural trends include (i) the entry in the market of publicly traded ﬂoriculture companies, (ii) external purchase by growers of main ﬂoral products supplying the North American market (Haines, 1998), and (iii) the increased horticultural production in high tunnels; the latter development can have direct impacts on plant disease management, including the enhanced possibility to make use of biological control (Carey et al., 2009; Pickett Pottorff and Panter, 2009). As with many other states of the USA, Florida’s ornamental plant nurseries underwent substantial structural changes in the 1980s/1990s (Hodges et al., 1996). In Florida, as in other states, slower market growth and an increasing competition has led to larger ﬁrms. At the same time, horticultural players tried to increase their product diversity. They also expanded their connectivity to distant markets, thus leading to a lower seasonality of sales. Adding long-distance trade connections to a horticultural system is likely to lower the threshold at which a plant disease epidemic may occur thus making it possible for diseases to become out of control – an insight obtained from network theory applied to trade pathways (Pautasso and Jeger, 2008). An additional trend is the shift in wholesale outlets from landscapers to retailers and other market channels (Andrade and Hinson, 2009). The vegetable greenhouse industry in Florida was surveyed in 1991, 1996, and 2001 (Tyson et al., 2001). A 50% increase in average acreage occurred over the 10 years investigated, together with changes in production media and dominant crops. Generally speaking, the evolution of the vegetable and wholesaler industries in the USA is a very rapid phenomenon (Perez, 1998; Park and McLaughlin, 2000; Hine et al., 2005). This rapidity makes the life of plant health inspectors harder, as measures aimed to counteract shifts and twists of the trade always take some time to be adopted fully. In Mexico, there is currently a rapid growth of the vegetable greenhouse industry (Steta, 2004). This has grown from 50 ha in 1991 to 350 ha in 1997, and from 1000 ha in 2001 to 2700 (estimated) in 2004. This development has been driven by the demand from the USA and by aggressive promotion of suppliers also from Europe. Increased links from Mexico to Europe and the USA could become a major pathway of plant pathogen introductions, especially in an age of climate warming. The vegetable greenhouse industry is seen as a key factor for creating technological innovation in the Mexican agriculture. There has also been a key role of the rapid development of the supermarket sector in Mexico in the 1990s for shaping the fruit and vegetable supply chain, with a shift away from traditional wholesalers (Schwentesius and Gomez, 2002). Structural change is affecting also the horticultural industry of South American countries (e.g. Faiguenbaum et al., 2002). Horticultural exports from Central and South America are increasing (Rae, 2004), particularly from countries such as Ecuador, Chile and, to some extent, Colombia (Lawson, 1996; del Banco Mundial, 2004; Pizarro Yanez, 2007). Increasing horticultural trade among South American countries and towards other continents will increase the likelihood that known and unknown pathogens from these regions will be introduced to and become established in previously unaffected cropland (Hodgetts et al., 2009).

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A report highlights the importance of biotechnology for the horticultural industry in Brazil (Cardoso Costa et al., 2006). This is also apparent in relation to plant diseases; for example, because of phytosanitary restrictions, there is an increasing demand for meristem-derived propagative material (Cardoso Costa et al., 2006; Öktem, 2006; Kalinina and Brown, 2007). Recent developments in DNA barcoding show that molecular techniques can provide novel diagnostic tools to contain the risk of introductions of exotic organisms through the horticultural trade (López-Moya et al., 2000; Skottrup et al., 2008; Seem, 2009; Glover et al., 2010). In Brazil as in other tropical countries, there is a tendency towards including new native ornamental species in the trade (Cavelier and Lee, 1999; Tombolato, 2006), which could enlarge the pool of potentially invasive exotic species to other countries. In Argentina, the vegetable production in the area surrounding Buenos Aires has experienced much modernization (Benencia and Souza Casadinho, 1993; Benencia, 1994; Benencia and Quaranta, 2003). In this as in other regions of South America, technological innovation coexists with the persistence of traditional working relations such as the migration of seasonal workers (Miranda, 1999). It is possible that such seasonal migrations also facilitate movement of plant pathogens. What we know is that cheap labour and transport are making horticultural products from countries such as Argentina, Brazil and Chile competitive for consumers in Australia and Japan (George et al., 2005).

ticulture in developing countries, however, has also implications for plant health, as in many cases knowledge about management of plant pathogens in these settings is limited (Prain et al., 2007). As in other continents, local supermarkets are increasingly inﬂuencing horticultural production, for example in Kenya (Neven and Reardon, 2004; Neven et al., 2009) and Egypt (Alaa, 2004). The trend towards concentration of the food retail trade implies on the one hand new opportunities to improve control for plant pathogens due to the decreased number of traders. On the other hand, the enlarged reach and magnitude of trade pathways make it more likely that, without control, long-distance spread of invasive species in general will occur. In Africa, the ornamental plant trade has been shown to lead to the escape and naturalization of introduced plant species (Waage et al., 2008). For example, the presence of exotic plant species in Kruger National Park, South Africa, is well correlated with historical human presence (Foxcroft et al., 2008). For Iridaceae from Southern Africa, introduction of a species to other regions has been shown to be strictly dependent on whether that species is being traded as an ornamental (Van Kleunen et al., 2007). Hence, increased trade and production of ornamentals will be associated with increased colonization and propagule pressure both for plant species and for their parasites and pathogens. This development is of concern, given that colonization and propagule pressures are key variables in determining the likelihood of success of exotic invasions (Lockwood et al., 2009; Simberloff, 2009).

2.2. Africa

2.3. Asia

A new trend affecting the international horticultural industry has been the development of exports from developing countries in the last 15–20 years (Lawson, 1996; Gehrig et al., 2009). For example, fruit and out-of-season vegetables produced in Zambia are exported almost exclusively to the UK, but not so much ornamentals (e.g. gladioli and roses) – these mostly go to the Netherlands (Anon, 1998). This pattern could have implications for the spread of diseases of fruit and vegetables vs. ornamentals, as the Netherlands are major redistributors for the European market. Market studies of ﬂoricultural (Anon, 1987) and horticultural products (Labaste, 2007) show the market potential for exporters in developing countries. In the 1990s, there has been an increasing export of fresh vegetables produced in a number of countries in sub-Saharan Africa. The production and the processing in Africa of these vegetables for export are structured by large retailers in Europe (Dolan and Humphrey, 2000) but adoption by African growers integrated in the international market of new technologies which can make plant disease management more effective is still patchy (Nzomoi et al., 2007). UK supermarkets have then joined an Ethical Trading Initiative to show their commitment to develop social welfare and environmental standards in the African horticultural industry (Hughes, 2001, 2006; Freidberg, 2003; Mannon, 2005; Hughes et al., 2008), but little attention has been given to the issue of unwanted plant pathogens (Areal et al., 2008). In Africa, horticulture has a long history (Janick, 2002; Greenﬁeld et al., 2005). However, only recently has horticulture in African urbanized areas become an important source of income, particularly for women (Moustier, 2007; Victor, 2007; Parrot et al., 2008). Although urban horticultural development can bring positive effects in terms of e.g. micro-credit projects and production of perishable vegetables in close proximity to consumers, there are also negative issues such as the poor working conditions and over-use of pesticides in many export-oriented ornamental farms (Maloba et al., 2008). Structural change in the international horticulture should not only be seen in the context of plant health, but also ﬁrst and foremost from the perspective of the health of horticultural workers and of the safety of the food produced (Diao, 2004; Levasseur et al., 2007; Cross et al., 2009a,b). The rise of urban hor-

Similar predictions are likely to hold also in Asia. The domestic seed market in Japan grew by a factor of 1.6 between 1980 and 1990, increasing in all seed sectors including ornamental plants (Maekawa, 1996). This was before the slowdown of the Japanese economy, which is now being experienced by the rest of the world. Whether economic recessions are accompanied by positive sideeffects such as a temporarily lower risk of exotic plant pathogen outbreaks due to the reduction in international trade does not seem to have occupied many minds lately. Even in a time of crisis, the Japanese horticultural industry is becoming increasingly internationalized. It is investing elsewhere in Asia where production costs are lower and from where producers can supply the Japanese market. At the same time, Japan’s horticulture is investing substantially in biotechnology. However, the private horticultural sector has many small enterprises and is thus relatively fragmented. It is therefore not surprising that Hemmi (1990) predicted that 25–30% of Japanese farms would have disappeared by 2000. Indeed, the share of the total income derived from agriculture for the average farm holding declined from 44% in 1965 to 13% in 1987. Many young farmers moved from state-controlled (rice) to uncontrolled products including ornamental plants and glasshouse horticulture. In 1980, Japan was almost entirely self-sufﬁcient for vegetables, but imports have grown rapidly in the last decades, due to low price and good quality of the imported horticultural products, and the aging horticultural farmers in Japan (Kawano, 2000). This development has implications for pest risk assessments in Japan. Vegetable seedling grafting is emerging as a technique to lower the risk of disease losses in Japan’s horticulture (Oda, 2007). As in the case of Japan, horticulture has a long tradition for China, where production of ornamentals is embedded in the traditional culture, and ﬂower cultivation had in the past assumed mystic connotations (Janick, 2003). The recent economic development in China has been accompanied by an even faster growth of the ﬂoral industry (Wang and Wu, 2007). This is one of the most dynamic and fastest-growing industries in China (Fang, 2005; Yang et al., 2008). The introduction of a ﬂower certiﬁcation system will improve the competitiveness of the Chinese industry on the international market and could help in diminishing the risk of importing

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and exporting new pests. However, the magnitude of the increase in the trade of ornamental plants from and to China could well offset any reduction in risk of introductions achieved with the adoption of best practices (Ding et al., 2008; He, 2009; Huang et al., 2009). A similar development can be observed for greenhouse horticulture (Qiu et al., 2008; Xue and Revell, 2009) and for soil-less production, whose area has grown from less than 1 ha at the beginning of the 1980s to more than 1000 ha in 2005 (Jiang and Yu, 2007, 2008). Soil-less horticulture has potential also in other Asian regions with poor soils and unreliable or excessive water availability (Montri and Wattananpreechanon, 2007; Irfanullah et al., 2008). Rapid production, higher yields and year-round availability are all factors contributing to the success of these innovative techniques (Campbell, 1994), but in the long-term they might be counterbalanced by new diseases adapted to plants growing in such enhanced conditions. In India, horticulture is becoming increasingly important to ensure sufﬁcient food for the growing human population (Kaul, 2008), but certiﬁcation issues to ensure plant health and product quality should not be disregarded (Kreamer and Kirby, 1994). Despite the increasing importance of India’s horticulture during the last decades, the lack of disease-free planting material is a limiting factor for many growers (Kaul, 1997). How climate change will affect the seasonal monsoon and the frequency of abnormal drought conditions may be an additional hurdle for India and neighbouring countries (Awasthi and Pareek, 2008; Johnson et al., 2009). 2.4. Australia and New Zealand In New Zealand, deregulation in 2001 has led to signiﬁcant changes in the apple industry (Dobbs and Rowling, 2006). This industry is currently described in New Zealand as in a state of turmoil, in spite of technological improvements, with many growers on the brink of ﬁnancial ruin, possibly due in part to the world oversupply of fruit. Apple production in the whole southern hemisphere is estimated at about 5 million tons for 2008, whilst China’s production in the same year reached around 27.5 million tons (from ca. 5 million tons 20 years before; van Schaik, 2008). Deregulation and privatization are likely to have affected also other horticultural sectors. For example, the previously government-funded horticulture extension service, a key factor in the country’s strategy to maintain plant health, has been seriously undermined by privatization (Warrington et al., 2004). Even for a remote country such as New Zealand, systematic control of all plant imports is unfeasible. The New Zealand government is thus moving to targeted surveillance for the pests posing the most potential risk to semi-natural ecosystems and to agriculture (Stephenson et al., 2003). The horticultural industry in Australia accounted for roughly 17% of total agricultural production by value in 1991/92 (Thompson and Kirby, 1994). Whilst most processed horticultural exports from Australia go to Europe or North America, fresh fruit export products are usually exported to Australia’s neighbours (e.g. Hong Kong, Indonesia, Malaysia and Singapore). Since 1990, Industry Development Ofﬁcers have facilitated knowledge exchange and the adoption of new technologies, linking actual and potential stakeholders (Mann and Thompson, 2006). Australia, however, possibly due to its geographically and historically isolated position, remains one of the few countries with a sound or at least strict policy regarding control of introductions of potential plant pathogens (Shivas et al., 2006; Rayment, 2006; Eagling, 2007). 2.5. Europe In Europe too there is a need for an increased appreciation of the consequences for the spread of agricultural diseases of the continuing reduction in trade barriers due to the European integration

and globalization processes (e.g. Brasier, 2005, 2008; Letode, 2005; Perrings et al., 2005; Gese, 2006; Klein, 2006; Arzt et al., 2010). In the current 25 European Union countries there are approximately 12,000 cultivars of 45 vegetable crops in cultivation (La Malfa and Bianco, 2006). Most cultivars are hybrids. New varieties are needed to create new products, to improve quality and to increase the sustainability of production. Janick (2005) argues that the selection process of new varieties has to reconcile production and processing aspects with current and anticipated consumer demands. We argue here that issues of plant health in a framework of long-term sustainability need to be considered. There is still very little information available across the EU on horticultural structural change. Jacobsen and Rothenburger (2004) provide a comparison of general trends in the horticulture production (industry structure, number of employees, area under cultivation, production levels, pesticide regulation) of various European countries (Belgium, Denmark, France, Germany, Hungary, the Netherlands, Spain). The EU harmonization of permitted phytosanitary chemicals is seen as a potential reduction in the competitive advantage of countries which still have not achieved much regulation of the usable active components of fungicides and insecticides. Jacobsen and Bokelmann (2004) analyse the competitiveness of the German horticultural sector compared to the one of various other European countries. They report that German horticulture has stricter environmental requirements than Southern European countries, but less than the Netherlands, Belgium and Denmark. These three countries also tend have a more favourable farm structure than in Germany, although this is compensated by the difﬁculties in recruiting seasonal workers. Odenstad and Holmstrom (1975) compare the inﬂuence of the increased energy prices due to the oil crisis of the 1970s on the horticultural sector for various Western European countries (Austria, Denmark, Finland, Great Britain, Italy, the Netherlands, Norway, Switzerland, and Western Germany), with more substantial impacts in colder countries. The issue of increases in energy prices on the economic outlook for horticultural growers could become again relevant should the oil supply become scarce in the near future. In this scenario, production may become even more convenient in countries with more favourable climate or where horticulture has adopted energy efﬁciency improvements and renewable energy technologies (van der Velden et al., 2004; Suri et al., 2007; Bakker et al., 2008; Vox et al., 2008; Bakker, 2009; Gruda et al., 2009). Not to be forgotten is also the impact of the EU enlargement on the horticultural industry of Eastern European nations, e.g. Hungary (Burger, 1996) and Poland (Holubowicz and Bralewski, 2004). From 1990 to 2000, in the former East Germany the fruit production area decreased by about 70%, the vegetable growing area was reduced to 15% of its original size, and the production of ornamentals in greenhouses was cut by about 80% (Bokelmann and Lentz, 2000). These numbers show how unconnected with developments in the West was the agriculture of these socialist countries. Although East Germany had many privately owned horticultural farms, their production capacity was often not enough to obtain a sufﬁcient income for family farms under market conditions. Horticultural cooperatives in East Germany had a larger size than the average farm in West Germany, but had lower capital equipment per land or labour unit, obsolescent machinery and techniques, and thus lower productivity (Bokelmann and Lentz, 2000). Nevertheless, in Eastern European countries other than the former East Germany, horticultural production has grown again after some structural reforms due to the lower labour prices. Eastern enlargement is thus having repercussions on the horticultural industry of EU countries themselves (e.g. Lehtimaki, 2002; Jacobsen and Bokelmann, 2004; Jacobsen and Rothenburger, 2004). Similar developments and interactions are taking place within the horticulture sector of the former Soviet Union (Onistschenko, 1981;

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Shumeiko, 1984; Shefﬁeld, 1996) and of Mediterranean countries such as Morocco and Turkey (Codron et al., 2004) but not much attention has been paid to how these developments need to be tackled from a plant health strategy perspective. For northern regions such as Scandinavia and Siberia, horticulture is still limited by winter temperatures and late spring frost (Khabarov, 1999) and production could be made easier by climate warming (although this may also complicate matters by facilitating the introduction and activity of plant pathogens and bugs (Parikka and Lemmetty, 2009; Tuovinen, 2009)). In Bulgaria and Albania, there is already a remarkable production of medicinal and aromatic plants, mainly ˜ et collected from the wild (Evstativea et al., 2008; Torres-Londono al., 2008). There is not just a need to improve the traceability and safety of the collected plant material (Mathe and Mathe, 2008), but also to assess the risk that this increasing trade could spread plant diseases. Zapata and Cortina (1984) show that the Spanish horticultural industry had to go through similar structural changes as currently experienced by Eastern European countries when Spain joined the European Community in 1986. More recently, Garcia Alonso et al. (2001) examine the relationships between employment, total costs and gross margins in the agrarian sector in Andalusia. Employment is the critical resource in crops with some kind of protection from weather vagaries. Economic efﬁciency of labour is higher in non-protected crops. An analysis of the productivity of Spanish cooperatives in the horticultural sector from 1994 to 2002 shows that efﬁciency has increased, possibly in relation to changes in management factors (labour quality, capital intensity and environmental performance; Galdeano-Gomez et al., 2006). Recent trends in the horticultural industry in Spain include the development of organic farming and a growing importance of products for export markets (Alvarez-Coque and Valdes, 1997; Nuez et al., 2002). A review of horticultural policy in France from the end of the 2nd World War to 1975 (Montigaud, 1978) suggests that this policy has followed the stages of the general economy: planned economy (1945–1955), return to liberalism (1955–1961), industrialization (1961–1970) and stabilization (1970–1975). In the Ile-de-France region, one of the most economically advanced parts of France, most horticultural enterprises are small (almost 80% have 1–2 paid employees), and two thirds of the ﬁrms are mainly involved with marketing (Anon, 1999). Such structural fragmentation may not make sense from a logistic and ﬁnancial point of view, but it is possible that it could be less risky from the point of view of plant disease epidemics, as it may avoid the presence of superconnected nodes, which typically tend to reduce the threshold for a disease to spread, other things being equal – another insight from network modelling (e.g. Jeger et al., 2007; Harwood et al., 2009; Moslonka-Lefebvre et al., 2009). At the whole country level, France is a leading importer of both fresh fruit and vegetables (mainly from Spain and Morocco), but it also re-exports much of its imports to Germany and other Northern European countries (Serrurier, 2009a,b). West Germany’s horticulture during the 1970s was affected by the two energy crises (1972/73 and 1979/80). These were accompanied by a substantial growth in unit size of enterprises (Storck, 1984), although this development in part pre-dated the oil crises (Rothenburger, 1973). Germany’s market for cut ﬂowers and ornamental plants has undergone fundamental structural change in the past 30 years due to changing consumer demand and supply conditions (Schmidt, 1996). Innovation has spurred an intensiﬁed competition. There are three main market types in the German horticultural industry: (i) a growing market for price conscious consumers of standard products (retailing chains); (ii) an expanding market for a large diversity of high quality pot plants (specialist retailers); and (iii) a declining market for cut ﬂowers and high quality ornamentals demanding high standard of services (direct-

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selling small-scale producers). New forms of wholesale business are evolving (all day rather than early morning). Specialized fruit producers in Germany are currently decreasing their acreage (cultivation methods are intensifying). However, on the whole the industry is losing enterprises, and a few big producing companies grow most of the fruit. Currently, production costs of many fruit types are often higher than the revenues from sales (Steinborn and Bokelmann, 2007). In the Lower Saxony region, organic apple production achieves lower yield but a better income than integrated production due to higher product prices and lower overall labour costs (due to shorter harvest times for a lower production; Fricke and Gorgens, 2009). If organic fruit cultivation becomes more widespread, there will be consequences for the management of diseases, with non-chemical control measures often implying higher labour costs in the short term (Zürcher et al., 2003; Holb, 2009; Jonssson et al., 2010), but probably a more sustainable growing practice in the long-term (Reganold et al., 2001; Stockdale et al., 2001; MacRae et al., 2007; Gomiero et al., 2008; Granado et al., 2008; Mondelaers et al., 2009; Raviv, 2010). Many of the 170 businessmen in the horticultural sector surveyed by Grabnitz and Bokelmann (2004) foresee an intensifying structural change in the future of the (German) horticultural industry, with an increasing concentration at the retail trade level, a rising importance of large-scale purchasers, and a diminution in the role of wholesalers. Also in Sweden, fewer and larger units are likely to develop in the horticultural system and trade of the next decades (Nerelius, 2002). In this country, already in the 1970s, 5% of the horticultural ﬁrms covered 40% of the total greenhouse area (Donelius, 1976). Unlike Sweden, Italy has a favourable climate for nursery and fruit production but an unfavourable size structure (too many small producers) compared with other European countries (Steffen, 1992; Guzmán et al., 2009). The Italian cut ﬂower production has been through various periods of crisis (Steffen, 1992; Lunati, 2007), but has recently managed to increase its international competitiveness (Asciuto et al., 2008). Cupo (1979) pointed out that, although ﬂoriculture was declining nationally (at least in terms of area covered), it was increasing in the south of Italy, so regional differences would also need to be considered. Southern Italian growers can beneﬁt from the generally milder climate compared to the North, but this may facilitate the introduction of new plant pathogens and pests (Greco and Inserra, 2008; Vacante and Bonsignore, 2009). Italy is still the second largest producer of ﬂowers in the EU and there are innovative international business prospects for young scions and rootstocks for easy transportation. Italian agriculture is at the forefront of commendable developments such as the denomination of protected origin and protected geographical indications (Miccolis, 2009), the Slow Food movement (Jones et al., 2003; Lotti, 2010), and organic cultivation (Elia and Conversa, 2009). With regard to fruit and vegetable production, Italy plays a similar role as France in the European market, with both internal production and re-export of crops produced in other Mediterranean countries (e.g. Israel, Egypt and Turkey) towards northern countries (Casa and Bernardi, 2009; Mulazzani and Malorgio, 2009). The Netherlands are by far the biggest producer of cut ﬂowers in Europe. They also have a key role as re-exporters of cut ﬂowers produced in developing countries (Lunati, 2007). Also in the Netherlands, structural change in the horticultural industry has been, and is, taking place (Anon, 1975; De Vroomen, 1978; Voskuilen, 1989; Van Oosten, 1998, 1999; Klink and Van Visser, 2004). Farms are increasing in size and decreasing in numbers (De Vroomen and De Groot, 1991). There have been implications of the ban on soil disinfectants for the Dutch bulb industry on the structure of bulb farms. Given the key role in plant trade of the Netherlands, it is particularly important that the development and widespread adoption of innovative growing systems be reconciled

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with plant health considerations (Van der Lans et al., 2008). This applies of course also to other countries with an important presence of horticultural exports (e.g. Greece: Olympios, 2002; Turkey: Gubbuk et al., 2004; Baris and Uslu, 2009; and Israel: Gera et al., 2006; Loebenstein, 2006; Shtienberg, 2007; Katan, 2009). In Israel, however, there has been a trend during the 1990s towards increased production for the local market rather than for export, which is becoming more focused towards niche products (Erez et al., 1999). This development, if sustained, could be beneﬁcial from a plant biosecurity perspective, but maybe counteracted by the concurrent increase of horticultural imports into Israel from other countries. As with other countries, the horticultural industry in the UK is undergoing structural change (Folley, 1979; Ilbery and Bowler, 1995a,b; Ogier, 1996). This is not just affecting production, but also the many people working in farms and glasshouses (Errington and Gasson, 1996). An interesting comparative analysis of the development of the horticultural sector in Poland vs. Great Britain (1991–2002) is provided by Jablonska and Gac (2006). Whilst fruit production decreased in the UK (−5% yearly), it increased in Poland (+3%). In 2002, British fruit crop production was equal to only 10% of Polish fruits produced. Whilst vegetable production decreased in the UK (−2% yearly), it increased in Poland (+7%), where the overall vegetable production is 2.5 times larger than in the UK. However, the UK produces more ornamental plants than Poland. These trends might have implications for the likelihood of outbreaks of diseases of these crops in the two countries. 2.6. The UK hardy nursery stock industry The review has not yet mentioned trade in woody plants. However, this sector is very important in the land-based industries both in economic terms and in its potential to spread diseases within and among countries (Izhevskii, 2008; Elliott, 2009; Mohanan, 2009; Evans et al., 2010). There are some aspects speciﬁc to the health of trees (long life and thus chronic stresses, compartimentalization of wood decay, size of canopies), but some of the issues related to structural change are relevant also to the production, trade and health of woody plants (Gibbs et al., 1998; Anselmi, 2007a,b; Jankovsky et al., 2007; Avanzato et al., 2009; Talgø, 2009). Tree nurseries are one of the main pathways for the introduction of exotic plant pathogens, as they often mask pathogen symptoms due to the excellent growing conditions and the application of biocides (mostly fungicides). Once tree saplings are planted, transplantation stress can be followed by the action of latent pathogens (Kriel et al., 2000; Hendry et al., 2002). Examples of such latent pathogens include Gremmeniella abietina (Zeng et al., 2005) and Sphaeropsis sapinea (Stanosz et al., 2001; Flowers et al., 2003). Tree nurseries might be involved in the rapid large-scale dispersal of Chalara fraxinea, an ascomycete fungus now associated with common ash (Fraxinus excelsior) dieback in many European countries, although evidence for such a role of nurseries is still piecemeal (Kowalski, 2006; Schumacher et al., 2007a,b; Halmschlager and Kirisits, 2008; Bakys et al., 2009a,b; Ioos et al., 2009; Jankovsky and Holdenrieder, 2009; Kowalski and Holdenrieder, 2008, 2009a,b; Ogris et al., 2009, 2010; Szabo, 2009; Talgø et al., 2009). For other tree pathogens, such as Phytophthora ramorum (Goss et al., 2009; Mascheretti et al., 2009), the regional and international dispersal role of nurseries is well established (see Section 3 ‘Implications for plant health’). As a case study, we summarize aspects of the UK hardy nursery sector of relevance for the future development of plant health in this and similar countries. A 1993 survey (the ﬁrst for 20 years) of the UK hardy nursery stock sector aimed to provide a systematic picture of the size and structure of the industry in England and Wales (Crane et al., 1993). Annual sales reached £230–250

million, with £180–200 million as container plants. Ornamental shrubs accounted for 60% of the industry by value. Seventy-ﬁve percent of the total output was produced in 10% of the holdings. The wholesale market was the most substantial outlet (∼60% of the sales). The survey was then further developed, with an analysis of growers’ attitudes to changes regarding the business (Crane and Barahona, 1996). Margins increased to a maximum with total sales of £200,000 but beyond that economies of scale were lost. Labour was the single largest cost of production. The timing of supply in relation to the timing of demand was studied for selected nursery stock lines (Wermund and Wainwright, 2000). Factors inﬂuencing demand were price promotions, public holidays, season, ﬂowering time and to a lesser extent weather. Already in the 1980s, ﬂowers were moving away from speciality to commodity items: only top quality ﬂowers then commanded high prices. The industry needs to concentrate on large-scale production and uniformity with new varieties to meet consumer demand (Mulder, 1989). However, concentrating on large-scale and uniform production might be disadvantageous in terms of plant health risks (Yachi and Loreau, 1999; Bengtsson et al., 2000; Holdenrieder et al., 2004; Pautasso et al., 2005; Tscharntke et al., 2007; Hummel et al., 2009). The competitiveness and cost structure of the Irish hardy nursery stock industry relative to the UK and the Netherlands was evaluated (Thorne et al., 2002). The high proportion of ﬁxed costs in the Netherlands may be creating an inﬂexible production system leading to a loss in competitiveness. In all three countries there were economies in scale as size increased from small to medium, but not from medium to large. Issues arising from the Competition Commission’s investigations into the activities of supermarkets were examined (Renwick, 2000). Sectors analysed included ﬂower, ornamental and hardy nursery stock. The results highlight the economic pressures on the horticultural sector with year-on-year reductions in proﬁtability and important penetration arising from monetary conversion. Additional burdens on growers can be caused by losses incurred when aggressive and generalist pathogens such as Phytophthora ramorum are detected and reported to plant health authorities (Lane et al., 2007). Technical innovations in the UK hardy nursery sector have been manifold. The use of plastic materials (e.g. greenhouse building materials) in nursery crops is one example (Antill, 1989). The practicalities and economics of micropropagation have been compared with rooted cuttings of trees and shrubs in the amenity sector (Dixon, 1987). Technical innovations result also in this sector in future opportunities (Howard, 1987), but micropropagation can result in increased susceptibility to pathogens as it results in the large-scale production of clonal plants. If changes likely to affect the UK horticulture in the future (including ornamentals; Dixon, 2000) are early recognized, then growers can make use of these developments to withstand concurrent undesirable effects. However, conclusions and recommendations for hardy ornamental nursery stock production (e.g. the use of peat alternatives; Glass, 1993) are available for all growers, so that there is no inherent advantage in obtaining information about new trends, the key issue is the application of the innovations. Technical innovations of the last years have included the hardy nursery stock container system. This has implications for the loss of nutrients and pesticide concentrations (Harris et al., 1997). An integrated crop management system for hardy nursery stock is in fact particularly important for minimizing the environmental impact of crop protection practices (Hall et al., 1998). Innovation in irrigation systems is likewise taking place and needs to be related to the risk of spreading Phytophthora species. These are pathogens which generally thrive in water re-circulating water, as shown for example by the newly discovered P. ramorum (Werres et al., 2007). A development which is likely to gain importance on the research

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agenda is how to mitigate climate change impacts of the horticultural industry, as well as how to mitigate the impact of climate change on garden and orchard plants (Bisgrove and Hadley, 2002; Linderholm, 2006; Campra et al., 2008; Wand et al., 2008; Blignaut et al., 2009; Luedeling et al., 2009; Mahmuti et al., 2009; Primack et al., 2009). Climate change may also provide an opportunity to horticulture, as this might be able to adapt to new growing conditions by moving to more suitable crops. There have been several developments in urban forestry and arboriculture, including attitudes of the many stakeholders, in the 1990s (Johnson, 2001a,b). Interesting is also the model for new industry development in horticulture by Collins (2005). Collins builds a growth model with discontinuous change (punctuated equilibrium) and argues that the biological and environmental science of developing a new crop species must consider new industries as emerging social systems with economic objectives. It is indeed increasingly recognized that the dynamics of plant pathosystems are not just limited to the host-pathogen-environment triangle, but are also shaped by human factors in a variety of ways (Scholthof, 2007). Transforming the structure of horticultural industries is only one of the ways through which human beings can shape pathosystems throughout the world.

Table 1 Summary of selected structural developments in the horticultural, ﬂoricultural and/or ornamental industries and the relative potential implications for plant health. In some cases these implications are posed as questions. Structural development in the industry

Potential implications for plant health

Increase in the supply exported to long-distance markets due to reductions in trade barriers

Potentially reduced epidemic threshold for plant diseases spread by trade

Inclusion of new ornamental species in the trade

Increased likelihood of introductions of invasive plants/novel pathogens outside their current distributional range

Growing seasonal migration of horticultural workers

Dissemination of crop management knowledge counterbalanced by higher possibility of exotic plant and pathogen invasions?

Rise of peri-urban horticulture in developing countries

Possible over-use of pesticides; need for more knowledge of plant disease management

Concentration of the food retail trade in a lower number of growers and retailers

Better potential for disease control due to decreased number of pathways, but increased risk due to increased capacity and long-distance connections

Introduction of certiﬁcation systems

Adoption of best practices for propagation can diminish risk of plant epidemics

Privatization of extension activities

Lower-quality availability of know-how in controlling epidemics?

Development of soil-less production

Increased yields but also potential for new diseases?

Adoption of organic/biological requirements

Lower potential for evolution of pathogen resistance to pesticides?

3. Implications for plant health One important issue which is often underestimated is the impact of structural change in the world’s horticultural industries for plant health. Obviously, the easier it becomes for horticultural and plantbased products to be shipped from continent to continent, the easier it is to supply satisfactorily consumer demands, but the easier it is also for plant pathogens and other associated organisms to be introduced in new regions (Bandyopadhyay and Frederiksen, 1999; Jones and Baker, 2007; Smith et al., 2007; van der Putten et al., 2007; Brenn et al., 2008; Heather and Hallman, 2008; Surkov et al., 2008a,b; Garibaldi and Gullino, 2009; Miller et al., 2009; Noble et al., 2009; Kaluza et al., in press). There is evidence both from CABI Abstracts and from the Web of Science that ﬁrst reports of plant pathogens in a certain region or country have been steadily increasing over the last two decades. The main structural changes mentioned in the previous sections and their potential implications for plant health are summarized in Table 1. In the following, we provide some examples of recent plant health issues which have arisen from some of the discussed structural developments.

Fig. 1. Network of trade interactions of European countries. Figure based on the sum of imports and exports of ornamental horticultural products (excluding seeds, 2003; from International Statistics Flowers and Plants, 2004). Arrow thickness is proportional to trade volume. Albania, Andorra, Iceland, Kosovo, Liechtenstein, Macedonia and San Marino not shown for lack of data.

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An example of how an increase in long-distance trade can have serious implications for the plant health of various regions is provided by the Asian (Anoplophora glabripennis) and Chinese longhorn beetle (A. chinensis) (Tomiczek and Hoyer-Tomiczek, 2007). Both are quarantine species in Europe which have been nonetheless introduced with imports of bonsai or through wood-packaging material. These species are polyphagous, with A. glabripennis preferring Acer, Salix and Populus, section Aigeiros, whilst A. chinensis also feeds on Citrus (Van der Gaag and Scholte, 2007; Caroulle, 2008; Hu et al., 2009). The Asian long-horn beetle is native to China and Korea, has been recently reported and apparently eradicated from Yokohama, Japan (Takahashi and Ito, 2005), but has become a dangerous pest in the USA, affecting a wide range of deciduous trees (Biaooki, 2003). A. glabripennis has been now reported in Austria, France, Germany and Poland where eradication still seems to be possible (Tomiczek and Hoyer-Tomiczek, 2007; but see Benker and Bogel, 2006, 2008; Krehan, 2008), whereas the area already affected by A. chinensis in Northern Italy in 2007 (200 km2 ) and the number of infested trees were already too large for eradication to be considered achievable (Herard et al., 2006; Tomiczek and Hoyer-Tomiczek, 2007). Another recent issue which has affected the hardy nursery stock industry of various countries (including the USA and the EU) is Phytophthora ramorum, the oomycete responsible for Sudden Oak Death in the West Coast of the USA and for a wide range of symptoms on several ornamental species grown in nurseries and sold in retail outlets throughout the world (Neubauer et al., 2006; Grünwald et al., 2008; Hüberli et al., 2008; Kaminski and Wagner, 2008; Moralejo et al., 2008). Both in the USA and Europe, the trade in ornamental species susceptible to this pathogen has contributed

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to the transmission of this emerging plant epidemic (Prospero et al., 2009; Vercauteren et al., 2010). Guidelines for best practice in nursery management tailored to P. ramorum and the control program have managed to contain the epidemic in the trade (Suslow, 2008a,b; Xu et al., 2009). However, for this as for other similar plant pathogens, there is still the need to integrate realistic models of the ornamental trade in risk mapping exercises and modeling of dispersal in heterogeneous landscapes (Kelly et al., 2008; Harwood et al., 2009). There are many other exotic organisms creating problems in the horticultural industry of many countries (Mumford, 2002; Baker et al., 2005; McCullough et al., 2006; Martensson, 2007; Smith et al., 2007; Cowie et al., 2008, 2009; Drew et al., in press). Key examples are the western ﬂower thrip Frankliniella occidentalis (Kirk and Terry, 2003; Du et al., 2005) and various other thrip species (Masumoto et al., 2005; Morse and Hoddle, 2006), including Thrips palmi (Vierbergen, 2001) and Gynaikothrips ﬁcorum (Reinert, 1983; Pelikan, 1991; Laudonia and Viggiani, 2005). A major problem for the horticultural and ﬂoricultural production of many countries is also posed by the vine weevil, Otiorhynchus sulcatus (Lozzia, 1983; del Bene and Parrini, 1986; Moorhouse et al., 1992; Montanari and Trentini, 1996). Not to be overlooked are also plant viruses and pathogenic bacteria (Elorriota et al., 2003; Garg, 2005; Gottula and Fuchs, 2009; Olivier et al., 2009). In the UK, important horticultural pests include New Zealand and Australian ﬂatworms (Alford et al., 1996; Cannon et al., 1999; Boag and Yeates, 2001) and the whiteﬂy Bemicia tabaci (a statutory pest in the UK associated with the importation of ornamental plants and the issue of virus transmission). In the latter case, the B-biotype has a broad host range and adaptability to new host plants with an increased risk of accidental introductions on a wider selection of plants and in different seasons (De Coursey Williams et al., 1996). Related to structural change in international agricultural production (and in some cases causing damage to growers as weeds) are also invasive plants introduced as ornamentals (Reichard and White, 2001; Levine and D’Antonio, 2003; Burt et al., 2007; Dehnen-Schmutz et al., 2007a,b; Anagnou-Veroniki et al., 2008; Pemberton and Liu, 2009). A similar threat to plant health is posed by trade in moss (Peck and Moldenke, in press), bonsai (Roques and Auger-Rozenberg, 2006) and timber, where a recent increase in long-distance connections and volume traded can be observed (Ciesla, 2004; Piel et al., 2008; Skarpaas and Okland, 2009).

4. Challenges for future plant health Much of the phytosanitary regulation adopted to diminish the risk of introductions has involved North America, Australia, New Zealand and Europe (Anon, 1995; Lawson, 1996; Brasier, 2008; Miller et al., 2009; Castonguay, 2010), but there is a need for a coordinated effort with the other regions now involved in the global horticultural trade. Regulation frameworks and quarantine programs should take on board a wider range of stakeholders than has been traditionally the case (Kenis et al., 2007; Murphy, 2007; MacLeod et al., in press; Table 2). A balance should be achieved among the necessity to make sure that food production is distributed throughout the planet so as to avoid local famines and malnutrition (Sen, 1991; Daily and Ehrlich, 1996; Hazell and Wood, 2008), the environmental impacts of horticulture (Rothenburger, 1987; Conforti and Giampietro, 1997; Pretty, 2008) and the enhanced risks to plant health due to increased trade (Nickle, 2003, 2008; Rossman, 2009; Mwebaze et al., 2010). In order to achieve this balance, new applications of network theory should be more frequently adopted by plant pathologists, as these are directly relevant for the spread of disease in trade

Table 2 Illustrative examples of practical steps that could be taken to reduce the risk of exotic plant pathogen introductions and establishment in spite of the structural changes in the horticultural industries (modiﬁed from Viljanen-Rollinson and Cromey, 2002; Bokelmann, 2007; Pagowska and Lipa, 2008; Drew et al., in press). Order does not convey importance. Practical recommendations Increase awareness of plant health in the public/stakeholder perception Target information and intervention to high-risk air and ship travelers (e.g. farmers, forestry workers, outdoor tourists, plant breeders and collectors) Make sure imported planting material goes through ofﬁcial quarantine procedures Concentrate control on super-connected trade players and major pathways, but stay aware of minor risks Establish surveillance and monitoring programs to achieve early detection of the establishment of new plant pathogens Connect agri-environment schemes with plant health considerations Increase funds available for plant disease research and education at Universities and Research Institutions Provide long-term ﬁnancial support to agencies and scientists preparing risk assessment studies for exotic plant pathogens Facilitate research dissemination, exchange and review Support interdisciplinarity and involvement in plant health science of climate scientists, economists, social scientists, landscape planners and botanists

pathways. A network approach could help diminish the threat of undesired introductions due to the increasing horticultural trade. Unfortunately, recent developments in network epidemiology have been so far largely ignored in plant health regulation (Jeger et al., 2007; Brasier, 2008; Rodoni, 2009; MacLeod et al., in press). Models of disease spread in complex networks suggest that in the case of heterogeneity in the contact structure of the trade players (Fig. 1), control should be targeted towards super-connected nodes (horticultural growers, retailers, or wholesalers with many in- and out-going trade connections). Worryingly, the structure of national and international horticultural trade networks is still poorly documented. Fig. 2 shows a good correlation between number of links and trade volume of ornamental horticultural products for the EU countries in 2003. This implies that variation in the strength of links (i.e. trade volume) is concurrent with variation in number of links, thus making the effect of the heterogeneity in the contact structure on epidemic thresholds even stronger. There is, however, some asymmetry between imports from and exports to a given country (four examples are provided in Fig. 3). It remains to be investigated whether such asymmetry in traded volume could reduce the epidemic threshold similarly to the effect of an absence of correlation

Fig. 2. A positive relationship between number of trade links to a certain EU-15 (+Norway & Switzerland) country and the value of the import to that country (again based on ornamental horticultural products excluding seeds, 2003). Both number of links and import values include all countries (also outside the EU) with which trade is taking place for this particular commodity (same source as with Fig. 1).

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Fig. 3. Correlation between imports and exports of ornamental horticultural products for four European countries (a: France, b: Germany, c: Italy, d: the Netherlands). Same data and source as with Fig. 1.

between number of links in and out of nodes (Moslonka-Lefebvre et al., 2009). Climate change is another factor which will affect most countries on the planet and can only be tackled in a coordinated way. From the horticultural viewpoint, climate change is likely to be less damaging than for extensive cultivations in non-controlled environments. But the potential risk posed by climate change for horticultural growers should not be unduly minimized, given its likely long-term effects on plant pathosystems (Coakley, 1995; Chakraborty et al., 2000; Salinari et al., 2004; Ghini et al., 2008; Jeger and Pautasso, 2008; Garibaldi and Gullino, 2009; Miller et al., 2009; Desprez-Loustau et al., 2010). Climate change is predicted for example to make the Australian horticultural industry more vulnerable to the Queensland fruit ﬂy (Bactrocera tryoni; Sutherst et al., 2000). Modest increases in temperature are expected to cause signiﬁcant additional costs to fruit growers and could jeopardize the industry’s competitiveness. Much research is being carried out on the potential effects of climate change on agricultural and seminatural ecosystems (Garibaldi et al., 2004; Blignaut et al., 2009; Booker et al., 2009; Donaldson, 2009; Primack and Miller-Rushing, 2009; Webb et al., 2010; Pautasso et al., in press), which makes it challenging to remain up-to-date with the literature (Fig. 4) and to disseminate it effectively to policy-makers, farmers and consumers. It is nonetheless becoming increasingly recognized that increases in the frequency of droughts and ﬂoods as well as in the ground-level concentration of ozone and other pollutants will pose a substantial challenge to food security. The increasingly globalized horticultural industry is an important factor in securing a diverse and reliable food supply for the whole of humanity. Change in the structure of this industry has been widespread and profound, with a general tendency towards fewer and larger growers, but also newer developments such as

the direct sale of plants to customers through the internet (Giltrap et al., 2009) and an increased role of cooperatives of producers (Alvarez-Coque et al., 2009; Riedel et al., 2009). These are probably developments which would have been inevitable even without the adoption of free trade policies and the increasingly easier transport of crops from continent to continent. However, comprehensive, long-term and multi-scale analyses of structural features of the world’s horticultural sector and of their implications for the long-range transport of plant pathogens are still needed. There is an urgent requirement to include plant health considerations in guidelines for best practice in the horticulture and ornamental pro-

Fig. 4. Proportion of papers on ﬁrst reports of plant pathogens in CABI Abstracts and Web of Science (1991–2009) as of January 2010.

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duction, as well as certiﬁcation schemes in international trade and local planting (Petit-Jean, 2008; Jullien, 2009). Acknowledgements Many thanks to A. Ambrosino, R. Baker, C. Brasier, J. England, A. Finley, T. Harwood, B. Ilbery, A. Inman, G. Jones, R. Little, A. MacLeod, D. Maye, P. Mills, M. Moslonka-Lefebvre, J. Mumford, L. Paul, S. Pietravalle, N. Salama, M. Shaw and X. Xu for insights and discussions, and to T. Matoni, R. Smith and anonymous colleagues for helpful comments on a previous draft. This review was inspired by attending the 9th International Congress of Plant Pathology in Turin, August 2008 and the 2nd Epidemics Conference in Athens, December 2009, and partly funded by the Rural Economy and Land Use (RELU) Programme, UK. References Alaa, E., 2004. Analysis of the strength and weakness of Egyptian market chains for horticultural crops. Acta Hort. 655, 143–147. Alford, D.V., Lole, M.J., Emmett, B.J., 1996. Alien terrestrial planarians in England & Wales, and implications for horticultural trade. In: Brighton Crop Protection Conf. on Pests and Diseases – 1996, Nov 18–21, Brighton England, pp. 1083–1088. Alvarez-Coque, J.M.G., Sexton, R., Lopez-Garcia Usach, T., 2009. Estrategias de cooperacion de los productores de frutas y hortalizas. Una comparacion trasatlantica. Revista de Economia Publica. Social y Cooperativa 65, 193–216. Alvarez-Coque, J.M.G., Valdes, A., 1997. Las tendencias recientes del comercio mundial de productos agrarios. Interdependencia entre ﬂujos y politicas. Una ˜ sintesis. Revista Espanola de Economia Agraria 181, 9–30. Anagnou-Veroniki, M., Papaioannou-Souliotis, P., Karanastasi, E., Giannopolitis, C.N., 2008. New records of plant pests and weeds in Greece, 1990–2007. Hell. Plant Prot. J 1, 55–78. Andrade, M.A.V., Hinson, R.A., 2009. Making the choice between rewholesalers and other nursery market channels. HortScience 44, 372–376. Anon, 1975. Der Gartenbau im Strukturwandel. 39 pp. Anon, 1987. Floricultural products. A study of major markets. 333 pp. Anon, 1995. Chrysanthemum white rust. In: Proceedings of the NAPPO-Agriculture and Agri-Food Canada Chrysanthemum White Rust Workshop, Ottawa, Canada, September 15–16, 1994, Bulletin – NAPPO (No. 14), 82 pp. Anon, 1998. The horticultural industry in Zambia. Hortic. Internac. 6, 62–63. Anon, 1999. The horticultural sector in the Ile-de-France region. Lien Horticole 36 (45), 7–8. Anselmi, N., 2007a. Difesa delle specie arboree ed arbustive impiegate per il verde urbano. Informatore Fitopatologico 57, 26–38. Anselmi, N., 2007b. Problematiche ﬁtopatologiche nella gestione delle alberate urbane. Italus Hortus 14, 52–58. Antill, D., 1989. The use of low-level plastics on horticultural ﬁeld crops. Profess. Hort. 3, 83–87. Areal, F.J., Touza, J., Macleod, A., Dehnen-Schmutz, K., Perrings, C., Palmieri, M.G., Spence, N.J., 2008. Integrating drivers inﬂuencing the detection of plant pests carried in the international cut ﬂower trade. J. Enviro. Manage. 89, 300–307. Arzt, J., White, W.R., Thomsen, B.V., Brown, C.C., 2010. Agricultural diseases on the move early in the third millennium. Veter. Path. 47, 15–27. Asciuto, A., Carapezza, R., Galati, A., Schimmenti, E., 2008. The competitiveness of the Italian ﬂower and ornamental plant sector. New Medit. 7, 26–37. Avanzato, D., Vaccaro, A., Bevilacqua, D., 2009. A short review of nut industry in EU. Acta Hortic. 825, 41–48. Awasthi, O.P., Pareek, O.P., 2008. Horticulture based cropping system for arid region – a review. Range Manage. Agrofor. 29, 67–74. Baker, R.H.A., Cannon, R., Bartlett, P., Barker, I., 2005. Novel strategies for assessing and managing the risks posed by invasive alien species to global crop production and biodiversity. Ann. Appl. Biol. 146, 177–191. Bakker, J.C., 2009. Energy saving greenhouses. Chron. Hort. 49 (2), 19–23. Bakker, J.C., Adams, S.R., Boulard, T., Montero, J.I., 2008. Innovative technologies for an efﬁcient use of energy. Acta Hort. 801, 49–62. Bakys, R., Vasaitis, R., Barklund, P., Ihrmark, K., Stenlid, J., 2009a. Investigations concerning the role of Chalara fraxinea in declining Fraxinus excelsior. Plant Path. 58, 284–292. Bakys, R., Vasaitis, R., Barklund, P., Thomsen, I., Stenlid, J., 2009b. Occurrence and pathogenicity of fungi in necrotic and non-symptomatic shoots of declining common ash (Fraxinus excelsior) in Sweden. Eur. J. For. Res. 128, 51–60. Bandyopadhyay, B., Frederiksen, R.A., 1999. Contemporary global movement of emerging plant diseases. Ann. New York Acad. Sci. 894, 28–36. Baris, M.E., Uslu, A., 2009. Cut ﬂower production and marketing in Turkey. Afr. J. Agr. Res. 4, 765–771. Benencia, R., 1994. Horticulture in the Buenos Aires green belt – productive and economic organization and changes in the labor market. Desar. Econ. – Rev. Cienc. Soc. 34 (133), 53–73. Benencia, R., Quaranta, G., 2003. Reestructuracion y contratos de medieria en la region pampeana argentina. Eur. Rev. Latin Am. Carib. Stud. 74, 65–83.

Benencia, R., Souza Casadinho, J., 1993. Alimentos y salud: uso y abuso de pesticidas en la horticultura bonaerense. Realidad Economica 114–115, 29–53. Bengtsson, J., Nilsson, S.G., Franc, A., Menozzi, P., 2000. Biodiversity, disturbances, ecosystem function and management of European forests. For. Ecol. Manage. 132, 39–50. Benker, U., Bogel, C., 2006. Zum Erstauftreten des Asiatischen Laubholzbockkafers Anoplophora glabripennis (Motschulsky, 1853)(Cerambycidae, Coleoptera) in Bayern. Mitt. Deut. Ges. allg. angew. Entomol. 15, 63–66. Benker, U., Bogel, C., 2008. Latest news from the Asian Longhorned Beetle Anoplophora glabripennis (Coleoptera, Cerambycidae) in Bavaria. Mitt. Deut. Ges. allg. angew. Entomol. 16, 121–124. Biaooki, P., 2003. Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae) – pierwsze stwierdzenie w Polsce. Ochrona Roslin 47 (11), 34–35. Bisgrove, R., Hadley, P., 2002. Gardening in the global greenhouse: the impacts of climate change on gardens in the UK, 139 pp. Blignaut, J., Ueckermann, L., Aronson, J., 2009. Agriculture production’s sensitivity to changes in climate in South Africa. South Afr. J. Sci. 105, 61–68. Boag, B., Yeates, G.W., 2001. The potential impact of the New Zealand ﬂatworm, a predator of earthworms, in western Europe. Ecol. Appl. 11, 1276–1286. Bokelmann, W., Lentz, W., 2000. The development of the horticultural sector in eastern Germany since 1990. Acta Hort. 524, 157–164. Bokelmann, W., 2007. The German approach of horticultural education. Acta Hort. 762, 401–406. Booker, F., Muntifering, R., McGrath, M., Burkey, K., Decoteau, D., Fiscus, E., Manning, W., Krupa, S., Chappelka, A., Grantz, D., 2009. The ozone component of global change: potential effects on agricultural and horticultural plant yield, product quality and interactions with invasive species. J. Integr. Plant Biol. 51, 337– 351. Brasier, C.M., 2005. Preventing invasive pathogens: deﬁciencies in the system. Plantsman 4 (1), 54–57. Brasier, C.M., 2008. The biosecurity threat to the UK and global environment from international trade in plants. Plant Pathol. 57, 792–808. Brenn, N., Menkis, A., Grünig, C.R., Sieber, T.N., Holdenrider, O., 2008. Community structure of Phialocephala fortinii s. lat. in European tree nurseries, and assessment of the potential of the seedlings as dissemination vehicles. Mycol. Res. 112, 650–662. Burger, A., 1996. Horticulture and environment in the Hungarian plain. Acta Hort. 429, 385–392. Burt, J.W., Muir, A.A., Piovia-Scott, J., Veblen, K.E., Chang, A.L., Grossman, J.D., Weiskel, H.W., 2007. Preventing horticultural introductions of invasive plants: potential efﬁcacy of voluntary initiatives. Biol. Inv. 9, 909–923. Campbell, L.C., 1994. Beneﬁcial impact of precision nutrient management on the environment and future needs. Comm. Soil Sci. Plant Anal. 25, 889–908. Campra, P., Garcia, M., Canton, Y., Palacios-Orueta, A., 2008. Surface temperature cooling trends and negative radiative forcing due to land use change toward greenhouse farming in southeastern Spain. J. Geophys. Res. – Atmospheres 113, D18109. Cannon, R.J.C., Baker, R.H.A., Taylor, M.C., Moore, J.P., 1999. A review of the status of the New Zealand ﬂatworm in the UK. Ann. Appl. Biol. 135, 597–614. Cardoso Costa, M.G., Xavier, A., Campos Otoni, W., 2006. Horticultural biotechnology in Brazil. Acta Hort. 725, 63–72. Carey, E.E., Jett, L., Lamont, W.J., Nennich, T.T., Orzolek, M.D., Williams, K.A., 2009. Horticultural crop production in high tunnels in the United States: a snapshot. Horttechnology 19, 37–43. Caroulle, F., 2008. Fiche sanitaire: les longicornes asiatiques. Forêts de France 516, 31–32. Casa, R.D., Bernardi, R., 2009. Ortofrutta tra globalizzazione e localizzazione. Informatore Agrario 65, 30–32. Castonguay, S., 2010. Creating an agricultural world order: regional plant protection problems and international phytopathology, 1878–1939. Agric. Hist. 84, 46–73. Cavelier, A., Lee, R., 1999. Ornamental potential of Colombian native ﬂora. Acta Hort. 482, 369–376. Chakraborty, S., Tiedemann, A.V., Teng, P.S., 2000. Climate change: potential impact on plant diseases. Enviro. Poll. 108, 317–326. Ciesla, W.M., 2004. Wood and Wood Products as Pathways for Introduction of Exotic Bark Beetles and Woodborers. CABI Publishing, Wallingford. Coakley, S.M., 1995. Biospheric change – will it matter in plant pathology. Can. J. Plant Path. 17, 147–153. Codron, J.M., Bouhsina, Z., Fort, F., Coudel, E., Puech, A., 2004. Supermarkets in lowincome Mediterranean countries: impacts on horticulture systems. Develop. Policy Rev. 22, 587–602. Collins, R.J., 2005. A model of new industry development in horticulture. Acta Hort. 694, 41–46. Conforti, P., Giampietro, M., 1997. Fossil energy use in agriculture: an international comparison. Agr. Ecos. Env. 65, 231–243. Cowie, R.H., Dillon, R.T., Robinson, D.G., Smith, J.W., 2009. Alien non-marine snails and slugs of priority quarantine importance in the United States: a preliminary risk assessment. Am. Malac. Bull. 27, 113–132. Cowie, R.H., Hayes, K.A., Tran, C.T., Meyer, W.M., 2008. The horticultural industry as a vector of alien snails and slugs: widespread invasions in Hawaii. Int. J. Pest Manage. 54, 267–276. Crane, R., Barahona, C., 1996. The economics of hardy nursery stock production in England. Spec. Stud. Agr. Econ., University of Reading (No. 32), 173 pp. Crane, R., Errington, A.J., Woodlock, P., 1993. Hardy nursery stock production in England and Wales. Spec. Stud. Agr. Econ. (No. 23), 35.

K. Dehnen-Schmutz et al. / Scientia Horticulturae 125 (2010) 1–15 Cross, P., Edwards, R.T., Nyeko, P., Edwards-Jones, G., 2009a. The potential impact on farmer health of enhanced export horticultural trade between the UK and Uganda. Int. J. Env. Res. Public Health 6, 1539–1556. Cross, P., Edwards, R.T., Opondo, M., Nyeko, P., Edwards-Jones, G., 2009b. Does farm worker health vary between localised and globalised food supply systems? Enviro. Int. 35, 1004–1014. Cupo, C., 1979. Linee e limiti della ﬂoricoltura del Mezzogiorno. Rassegna Economica 43, 421–437. Daily, G.C., Ehrlich, P.R., 1996. Socioeconomic equity, sustainability, and Earth’s carrying capacity. Ecol. Appl. 6, 991–1001. De Coursey Williams, M., Bedford, I.D., Kelly, A., Markham, P.G., 1996. Bemisia tabaci: potential infestation and virus transmission within the ornamental plant industry. In: Brighton Crop Protection Conf. on Pests and Diseases – 1996, Nov 18–21, Brighton, England, pp. 63–68. De Groot, N.S.P., 1999. Floriculture worldwide trade and consumption patterns. Acta Hort. 495, 101–121. De Vroomen, C.O.N., 1978. Recent developments in the structure of nursery holdings in the ﬂower bulb district (of the Netherlands). Bedrijfsonwikkeling 9, 1023–1028. De Vroomen, C.O.N., De Groot, N.S.P., 1991. Bulb growing on sandy soils in the Netherlands without soil disinfectants. Acta Hort. 295, 47–52. Dehnen-Schmutz, K., Touza, J., Perrings, C., Williamson, M., 2007a. The horticultural trade and ornamental plant invasions in Britain. Conserv. Biol. 21, 224–231. Dehnen-Schmutz, K., Touza, J., Perrings, C., Williamson, M., 2007b. A century of the ornamental plant trade and its impact on invasion success. Divers. Distrib. 13, 527–534. del Banco Mundial, D., 2004. Colombia: competitividad agricola y rural. Planeacion y Desarrollo 35, 5–207. del Bene, G., Parrini, C., 1986. Note sulla biologia di specie di Otiorrhynchus (Coleoptera Curculionidae) dannose a piante ornamentali in vivai della Toscana. Redia 69, 341–359. Dempster, D., 1989. Implications of the Canada–United States trade agreement for horticulture in Canada. Can. J. Agr. Econ. 37, 1277–1282. Desprez-Loustau, M.L., Courtecuisse, R., Robin, C., Husson, C., Moreau, P.A., Blancard, D., Selosse, M.A., Lung-Escarmant, B., Piou, D., Sache, I., 2010. Species diversity and drivers of spread of alien fungi (sensu lato) in Europe with a particular focus on France. Biol. Inv. 12, 157–172. Diao, M.B., 2004. Situation et contraintes des systemes urbains et periurbains de production horticole et animale dans la region de Dakar. Cahiers Agricultures 13, 39–49. Ding, J., Mack, R.N., Lu, P., Ren, M., Huang, H., 2008. China’s booming economy is sparking and accelerating biological invasions. BioScience 58, 317–324. Dixon, G.R., 1987. The practicalities and economics of micropropagation for the amenity plant trade. Micropropagation in horticulture: practise and commercial problems. In: Proc. Inst. Hort. Symp., Univ. Nottingham School of Agriculture, 24–26 March 1986, pp. 183–196. Dixon, G., 2000. Changing fortunes. Horticulturalist 9, 7–9. Dobbs, M., Rowling, D., 2006. Revisiting the New Zealand apple industry: the impacts of change. Brit. Food J. 108, 574–585. Dolan, C., Humphrey, J., 2000. Governance and trade in fresh vegetables: the impact of UK supermarkets on the African horticulture industry. J. Develop. Stud. 37, 147–176. Donaldson, J.S., 2009. Botanic gardens science for conservation and global change. Trends Plant Sci. 14, 608–613. Donelius, H.G., 1976. Large-scale horticultural green house production – a preliminary analysis of growth and scale effects in 128 Swedish nurseries. Acta Hort. 55, 167–177. Drew, J., Anderson, N., Andow, D. Conundrums of a complex vector for invasive species control: a detailed examination of the horticultural industry. Biol. Inv., doi:10.1007/s10530-010-9689-8, in press. Du, Y.Z., Dai, L., Ju, R.T., Gu, J., Diao, C.Y., Gong, W.R., 2005. Risk analysis of alien invasive western ﬂower thrips, Frankliniella occidentalis (Pergande), in China. Sci. Agr. Sin. 38, 2360–2364. Eagling, D., 2007. Australian trade in agricultural food products – the challenge for plant pathologists. Australas. Plant Pathol. 36, 539–542. Elia, A., Conversa, G., 2009. Innovazione e qualità per il futuro dell’orticoltura. Informatore Agrario 65, 60–61. Elliott, M.L., 2009. Emerging plant diseases in Florida. HortTechnology 19, 717– 718. Elomaa, P., Joensuu, J.J., Korpelainen, H., Makinen, K., Niklander-Teeri, V., Pirhonen, M., Seppanen, M.M., Teeri, T.H., Valkonen, J.P.T., 2008. Plant biotechnology for deeper understanding, wider use and further development of agricultural and horticultural crops. Agr. Food Sci. 17, 307–324. Elorriota, M.A., Suarez-Estrella, F., Lopez, M.J., Vargas-Garcia, M.C., Moreno, J., 2003. Survival of phytopathogenic bacteria during waste composting. Agr. Ecosyst. Env. 96, 141–146. Erez, A., Spharim, I., Shalhevet, S., 1999. Horticultural research in Israel: past, present and future. Acta Hortic. 495, 439–447. Errington, A., Gasson, R., 1996. The increasing ﬂexibility of the farm and horticultural workforce in England and Wales. J. Rural Stud. 12, 127–141. Evans, H.C., Waller, J.M., 2010. Globalisation and the threat to biosecurity. In: Strange, R.N., Gullino, M.L. (Eds.), The Role of Plant Pathology in Food Safety and Food Security. Springer, Berlin, pp. 53–71. Evans, E.A., Crane, J., Hodges, A., Osborne, J.L., 2010. Potential economic impact of laurel wilt disease on the Florida avocado industry. HortTechnology 20, 234– 238.

11

Evstativea, L., Hardalova, R., Stoyanova, K., 2008. Trade and protection of medicinal and aromatic plants in Bulgaria. Zeitschrift für Arznei und Gewürzpﬂanzen 13, 151–152. Faiguenbaum, S., Berdegue, J.A., Reardon, T., 2002. The rapid rise of supermarkets in Chile: effects on dairy, vegetable, and beef chains. Develop. Policy Rev. 20, 459–471. Fang, Z.Y., 2005. Development of the horticultural industry and horticultural science and technology in China. J. Hort. Sci. Biotech. 80 (5), 511. Flowers, J., Hartman, J., Vaillancourt, L., 2003. Detection of latent Sphaeropsis sapinea infections in Austrian pine tissues using nested-polymerase chain reaction. Phytopathology 93, 1471–1477. Folley, R.R.W., 1979. Structure and scale in horticultural crop enterprises – basis of classiﬁcation. J. Agr. Econ. 30, 59–61. Foxcroft, L.C., Richardson, D.M., Wilson, J.R.U., 2008. Ornamental plants as invasive aliens: problems and solutions in Kruger National Park, South Africa. Enviro. Manage. 41, 32–51. Freidberg, S., 2003. Cleaning up down South: supermarkets, ethical trade and African horticulture. Soc. Cult. Geogr. 4, 27–43. Fricke, K., Gorgens, M., 2009. BIO: tiefere Erntemenge – bessere Preise. Schw. Z. ObstWeinbau 41, 289–293. Furtan, W.H., Van Melle, B.M., 2004. Canada’s agricultural trade in north America: do national borders matter? Rev. Agr. Econ. 26, 317–331. Galdeano-Gomez, E., Cespedes-Lorente, J., Rodriguez-Rodriguez, M., 2006. Productivity and environmental performance in marketing cooperatives: an analysis of the Spanish horticultural sector. J. Agr. Econ. 57, 479–500. Gamliel, A., 2008. High consequence plant pathogens. In: Gullino, M.L., Fletcher, J., Gamliel, A., Stack, J.P. (Eds.), Crop Bio-security: Assuring our Global Food Supply. Nato Science for Peace and Security Series C – Environmental Security, pp. 25–36. Garcia Alonso, C.R., Martin Lozano, J.M., Perez Hernandez, P.P., 2001. Structure and economy of protected crops in Andalucia: a comparative research. Acta Hort. 559, 699–704. Garg, I.D., 2005. Virus and virus-like diseases of potato and their management. In: Sharma, R.C., Sharma, J.N. (Eds.), Challenging Problems in Horticultural and Forest Pathology. Indus Publishing Company, New Delhi, pp. 200–222. Garibaldi, A., di San Lio, G.M., Gullino, M.L., 2004. Alcune considerazioni sui problemi ﬁtopatologici emergenti delle colture ornamentali. Informatore Fitopatologico 54, 19–32. Garibaldi, A., Gullino, M.L., 2009. Malattie emergenti su colture ornamentali nell’Italia settentrionale e aggiornamenti sulla difesa. Protezione delle Colture 4, 13–19. Gehrig, J., Masiunas, J., Itulya, F., Mwaja, V., 2009. The Kenyan export horticulture industry. Hortscience 44 (4), 1101. George, A.P., Broadley, R.H., Nissen, R.J., 2005. Can Australian horticulture survive and meet the global challenge? Acta Hort. 694, 289–294. Gera, A., Maslenin, L., Rosner, A., Zeidan, M., Weintraub, P.G., 2006. Phytoplasma diseases in ornamental crops in Israel. Acta Hortic. 722, 155–161. Gese, K., 2006. Die Phytosanitäre Grenzkontrollstelle Frankfurt/Main-Flughafen stellt sich vor. Gesunde Pﬂanzen 58, 201–204. Ghini, R., Hamada, E., Bettiol, W., 2008. Climate change and plant diseases. Scientia Agricola 65, 98–107. Gibbs, J.N., MacAskill, G.A., Lonsdale, D., Rose, D.R., Tilbury, C.A., 1998. The health of non-woodland trees in England in 1998. Arboricult. Res. Info. Note 147, 8. Giltrap, N., Eyre, D., Reed, P., 2009. Internet sales of plants for planting – an increasing trend and threat? EPPO Bull. 39, 168–170. Glass, P., 1993. A study of ornamental nursery stock and an investigation into peat alternatives in Europe and North America. 47 pp. Glover, R.H., Collins, D.W., Walsh, K., Boonham, N., 2010. Assessment of loci for DNA barcoding in the genus Thrips (Thysanoptera: Thripidae). Molec. Ecol. Res. 10, 51–59. Gomiero, T., Paoletti, M.G., Pimentel, D., 2008. Energy and environmental issues in organic and conventional agriculture. Crit. Rev. Plant Sci. 27, 239–254. Goss, E.M., Larsen, M., Chastagner, G.A., Givens, D.R., Grünwald, N.J., 2009. Population genetic analysis infers migration pathways of Phytophthora ramorum in US nurseries. PLoS Path. 5, e1000583. Gottula, J., Fuchs, M., 2009. Toward a quarter century of pathogen-derived resistance and practical approaches to plant virus disease control. Adv. Virus Res. 75, 161–183. Grabnitz, D., Bokelmann, W., 2004. Trends and tendencies – how experts of the horticultural sector expect business environment in the future. Acta Hort. 655, 225–232. Granado, J., Thurig, B., Kieffer, E., Petrini, L., Fliessbach, A., Tamm, L., Weibel, F.P., Wyss, G.S., 2008. Culturable fungi of stored ‘golden delicious’ apple fruits: a one-season comparison study of organic and integrated production systems in Switzerland. Micr. Ecol. 56, 720–732. Greco, N., Inserra, R.N., 2008. Exotic and non-exotic nematode plant pests: a potential threat to the Italian agriculture and environment. Redia 91, 103–109. Greenﬁeld, H.J., Fowler, H.D., Van Schalkwyk, L.O., 2005. Where are the gardens? Early iron age horticulture in the Thukela River Basin of South Africa. World Archaeol. 37, 307–328. Gruda, N., Ruhm, G., Bokelmann, W., Schmidt, U., 2009. Die Auswirkung von Heizölpreissteigerungen auf sächsische Gartenbauunternehmen - Teil I: Ausgangsund Energiesituation der Unterglasbetriebe. Berichte über Landwirtschaft 87 (1), 87–105. Grünwald, N.J., Goss, E.M., Press, C.M., 2008. Phytophthora ramorum: a pathogen with a remarkably wide host range causing sudden oak death on oaks and ramorum blight on woody ornamentals. Mol. Plant Path. 9, 729–740.

12

K. Dehnen-Schmutz et al. / Scientia Horticulturae 125 (2010) 1–15

Gubbuk, H., Polat, E., Pekmezci, M., 2004. Organic fruit production in Turkey. J. Fruit Ornam. Plant Res. 12, S23–S29. Gullino, M.L., Garibaldi, A., 2007. Critical aspects in management of fungal diseases of ornamental plants and directions in research. Phytopath. Medit. 46, 135–149. Guzmán, I., Arcas, N., Guelﬁ, R., Rivaroli, S., 2009. Technical efﬁciency in the fresh fruit and vegetable sector: a comparison study of Italian and Spanish ﬁrms. Fruits 64, 243–252. Haines, B., 1998. North American ﬂoriculture market consolidation. Flora Cult. Int. 8, 24–28. Hall, A., Slaney, L., Stevenson, R., 1998. A feasibility study on the use of integrated crop management for outdoor ornamentals. In: Brighton Crop Protection Conf.: Pests and Diseases – 1998, 16–19 November 1998, Brighton, England, pp. 619–624. Halmschlager, E., Kirisits, T., 2008. First report of the ash dieback pathogen Chalara fraxinea on Fraxinus excelsior in Austria. Plant Path. 57, 1177. Harris, G.L., Hodgkinson, R.A., Scott, M., Mason, D.J., Pepper, T.J., 1997. Impact of hardy ornamental nursery stock (HONS) systems on the environment: losses of nutrients and agrochemicals. Agr. Water Manage. 34, 95–110. Harrison, K.M., 2003. World trends driving horticultural expansion in emerging economies. In: De Groot, N., Wilson, G. (Eds.), Horticultural Science in Emerging Economies: Issues and Constraints. 26th Int. Hort. Congress, Aug 11–17, 2002, Toronto, Canada, pp. 115–125. Harwood, T.D., Xu, X.M., Pautasso, M., Jeger, M.J., Shaw, M.W., 2009. Epidemiological risk assessment using linked network and grid based modelling: Phytophthora ramorum and P. kernoviae in the UK. Ecol. Model 220, 3353–3361. Hazell, P., Wood, S., 2008. Drivers of change in global agriculture. Phil. Trans. R. Soc. B 363, 495–515. He, F.L., 2009. Price of prosperity: economic development and biological conservation in China. J. Appl. Ecol. 46, 511–515. Heather, N.W., Hallman, G.J., 2008. Pest Management and Phytosanitary Trade Barriers. CABI Publishing, Wallingford. Hemmi, K., 1990. Recent development in Japanese agricultural structure and its future prospects. Agr. Policy Proc. 164, 41–48. Hendry, S.J., Boddy, L., Lonsdale, D., 2002. Abiotic variables effect differential expression of latent infections in beech (Fagus sylvatica). New Phytol. 155, 449– 460. Herard, F., Ciampitti, M., Maspero, M., Krehan, H., Benker, U., Boegel, C., Schrage, R., Bouhout-Delduc, L., Bialooki, P., 2006. Anoplophora species in Europe: infestations and management processes. Bull. OEPP 36 (3), 470–474. Hine, S., Pritchett, J., Loureiro, M.L., Meyer, S., 2005. Vertical integration in produce markets: a Colorado cooperative’s strategic response to change. J. Agribus. 23, 93–108. Hodges, A.W., Haydu, J.J., Van Blockland, P.J., 1996. Adaptation to competition and structural change in Florida’s ornamental plant nursery industry, 1989–1994. In: Brumﬁeld, R.G. (Ed.), XIII Int. Symp. Hort. Econ., vol. 429, Aug 04–09, 1996, Rutgers, New Brunswick, NJ, pp. 309–316. Hodgetts, J., Chuquillangui, C., Muller, G., Arocha, Y., Gamarra, D., Pinillos, O., Velit, E., Lozada, P., Boa, E., Boonham, N., Mumford, R., Barker, I., Dickinson, M., 2009. Surveys reveal the occurrence of phytoplasmas in plants at different geographical locations in Peru. Ann. Appl. Biol. 155, 15–27. Hoffmann, D., 2009. Der Weinmarkt in der Welt. Agrarwirtschaft 58 (1), 83–90. Holb, I.J., 2009. Fungal disease management in environmentally friendly apple production – a review. In: Lichtfouse, E. (Ed.), Climate Change, Intercropping, Pest Control and Beneﬁcial Microorganisms. Springer, New York, pp. 219–292. Holdenrieder, O., Pautasso, M., Weisberg, P.J., Lonsdale, D., 2004. Tree diseases and landscape processes: the challenge of landscape pathology. Trends Ecol. Evol. 19, 446–452. Holubowicz, R., Bralewski, T.W., 2004. Strategies of development of horticultural breeding and seed production companies after Poland joins the European Union. Folia Universitatis Agriculturae Stetinensis 95, 127–130. Howard, B.H., 1987. Micropropagation in horticultural perspective, pp. 1–13. Micropropagation in horticulture: practise and commercial problems. In: Proc. Inst. Hort. Symp., Univ. Nottingham School of Agriculture, 24–26 March 1986. Hu, J., Angeli, S., Schuetz, S., Luo, Y., Hayek, A.E., 2009. Ecology and management of exotic and endemic Asian longhorned beetle Anoplophora glabripennis. Agr. For. Entom. 11, 359–375. Huang, Q.Q., Wu, J.M., Bai, Y.Y., Zhou, L., Wang, G.X., 2009. Identifying the most noxious invasive plants in China: role of geographical origin, life form and means of introduction. Biodiv. Conserv. 18, 305–316. Hüberli, D., Lutzy, B., Voss, B., Calver, M., Ormsby, M., Garbelotto, M., 2008. Susceptibility of New Zealand ﬂora to Phytophthora ramorum and pathogen sporulation potential: an approach based on the precautionary principle. Australas. Plant Path. 37, 615–625. Hughes, A., 2001. Global commodity networks, ethical trade and governmentality: organizing business responsibility in the Kenyan cut ﬂower industry. Trans. Inst. Brit. Geog. 26, 390–406. Hughes, A., 2006. Geographies of exchange and circulation: transnational trade and governance. Prog. Human Geog. 30, 635–643. Hughes, A., Wrigley, N., Buttle, M., 2008. Global production networks, ethical campaigning, and the embeddedness of responsible governance. J. Econ. Geog. 8, 345–367. Hulme, P.E., 2009. Trade, transport and trouble: managing invasive species pathways in an era of globalization. J. Appl. Ecol. 46, 10–18. Hummel, S., Donovan, G.H., Spies, T.A., Hemstrom, M.A., 2009. Conserving biodiversity using risk management: hoax or hope? Front. Ecol. Enviro. 7, 103–109. Humphrey, J., 2006. Horticulture: responding to the challenges of poverty reduction and global competition. Acta Hort. 699, 19–41.

Ilbery, B.W., Bowler, I.R., 1995a. Britain’s uncertain future in the international horticultural market. Outlook Agr. 24, 4–55. Ilbery, B.W., Bowler, I.R., 1995b. Horticultural change and the horticultural buildings and orchard replanting grant scheme in England. Enviro. Plan. C 13, 67–78. International Statistics Flowers and Plants, 2004. Institut für Gartenbauökonomie der Universität Hannover, Germany, vol. 52. Ioos, R., Kowalski, T., Husson, C., Holdenrieder, O., 2009. Rapid in planta detection of Chalara fraxinea by a real-time PCR assay using a dual-labelled probe. Eur. J. Plant Path. 125, 329–335. Irfanullah, H.M., Adrika, A., Ghani, A., Khan, Z.A., Rashid, M.A., 2008. Introduction of ﬂoating gardening in the north-eastern wetlands of Bangladesh for nutritional security and sustainable livelihood. Renew. Agr. Food Syst. 23, 89–96. Izhevskii, S.S., 2008. New pest of conifers in Europe. Zashchita i Karantin Rastenii 6, 35. Jablonska, L., Gac, P., 2006. Analiza porownawcza sektora ogrodniczego w Polsce i Wielkiej Brytanii [A comparative analysis of the horticultural sector in Poland and Great Britain]. Annales Universitatis Mariae Curie-Sklodowska. Sectio EEE. Horticultura 16, 155–164. Jacobsen, B., Bokelmann, W., 2004. Analysis of the competitiveness of the German horticultural sector. Acta Hort. 655, 365–370. Jacobsen, B., Rothenburger, W., 2004. Wettbewerbssituation des deutschen Gartenbaus im europäischen Vergleich – Analyse ausgewählter wichtiger Wettbewerbsfaktoren in der Gartenbauwirtschaft. Schriftenreihe des Bundesministeriums für Verbraucherschutz, Ernährung und Landwirtschaft, Reihe A, Angewandte Wissenschaft No. 504, 322 pp. Janick, J., 2002. Ancient Egyptian agriculture and the origins of horticulture. Acta Hort. 582, 23–39. Janick, J., 2003. History of Asian horticultural technology. Acta Hort. 620, 19–32. Janick, J., 2005. Horticultural plant breeding: past accomplishments, future directions. Acta Hort. 694, 61–65. Janick, J., 2007. The origins of horticultural technology and science. Acta Hort. 759, 41–60. Jankovsky, L., Bednarova, M., Haltofova, P., Palovcikova, D., 2007. The risk of introducing quarantine pests of importance to forest nurseries and forests in the Czech Republic. Comm. Inst. For. Bohem. 23, 67–72. Jankovsky, L., Holdenrieder, O., 2009. Chalara fraxinea – ash dieback in the Czech Republic. Plant Prot. Sci. 45, 74–78. Jeger, M.J., Pautasso, M., 2008. Plant disease and global change – the importance of long-term data sets. New Phytol. 177, 8–11. Jeger, M.J., Pautasso, M., Holdenrieder, O., Shaw, M.W., 2007. Modelling disease spread and control in networks: implications for plant sciences. New Phytol. 174, 179–197. Jiang, W.J., Yu, H.J., 2007. Twenty years development of soilless culture in Mainland China. Acta Hort. 759, 181–186. Jiang, W.J., Yu, H.J., 2008. Present situation and future development for protected horticulture in Mainland China. Acta Hort. 770, 29–35. Johnson, G.I., Weinberger, K., Wu, M.H., 2009. The vegetable sector in tropical Asia: importance, issues and a way ahead. Acta Hort. 809, 15–34. Johnson, M., 2001a. British urban forestry in transition - developments between 1993–1998, Part I. Arboric. J. 25, 59–92. Johnson, M., 2001b. British urban forestry in transition – developments between 1993–1998, Part II. Arboric. J. 25, 153–178. Jones, D.R., Baker, R.H.A., 2007. Introductions of non-native plant pathogens into Great Britain, 1970–2004. Plant Path. 56, 891–910. Jones, P., Shears, P., Hillier, D., Comfort, D., Lowell, J., 2003. Return to traditional values? A case study of Slow Food. Brit. Food J. 105, 297–304. Jonssson, A., Nybom, H., Rumpunen, K., 2010. Fungal disease and fruit quality in an apple orchard converted from integrated production to organic production. J. Sust. Agric. 34, 15–37. Jullien, J., 2009. Integrer les risques phytosanitaires des la conception paysagere. PHM Revue Horticole 510, 27–33. Kalinina, A., Brown, D.C.W., 2007. Micropropagation of ornamental Prunus spp. and GF305 peach, a Prunus viral indicator. Plant Cell Rep. 26, 927–935. Kaluza, P., Kölzsch, A., Gastner, M.T., Blasius, B., 2010. The complex network of global cargo ship movements. J. R. Soc. Interface, doi:10.1098/rsif.2009.0495, in press. Kaminski, K., Wagner, S., 2008. In vitro inoculation studies for estimating the susceptibility of ornamental plants to Phytophthora ramorum. J. Phytopath. 156, 480–486. Katan, J., 2009. Phytopathology in Israel: nine decades of research. Phytoparasitica 37, 333–336. Kaul, G.L., 1997. Horticulture in India – production, marketing and processing. Ind. J. Agr. Econ. 52, 561–573. Kaul, G.L., 2008. Horticulture and nutritional security strategies for sustained development of horticulture in India. Comp. Rev. Food Sci. Food Safety 7, 324–328. Kawano, T., 2000. Japan’s recent increasing import of horticultural produce. Acta Hort. 524, 117–129. Kelly, M., Liu, D.S., McPherson, B., Wood, D., Standiford, R., 2008. Spatial pattern dynamics of oak mortality and associated disease symptoms in a California hardwood forest affected by sudden oak death. J. For. Res. 13, 312–319. Kenis, M., Rabitsch, W., Auger-Rozenberg, M.-A., Roques, A., 2007. How can alien species inventories and interception data help us prevent insect invasions? Bull. Entom. Res. 97, 489–502. Khabarov, S.N., 1999. Ampliﬁcation of the biogenesis of intensiﬁcation processes in Siberian horticulture. Main directions. Russ. Agr. Sci. 7, 14–21. Kirk, W.D.J., Terry, L.I., 2003. The spread of the western ﬂower thrips Frankliniella occidentalis (Pergande). Agr. For. Entom. 5, 301–310.

K. Dehnen-Schmutz et al. / Scientia Horticulturae 125 (2010) 1–15 Klein, W., 2006. Der bayerische Pﬂanzenschutzdienst stellt sich vor. Gesunde Pﬂanzen 58 (1), 3–8. Klink, A., Van Visser, E.J., 2004. Innovation in Dutch horticulture: fresh ideas in fresh logistics. Tijdschrift voor Economische en Sociale Geograﬁe 95, 340– 346. Kowalski, T., 2006. Chalara fraxinea sp nov associated with dieback of ash (Fraxinus excelsior) in Poland. Forest Path. 36, 264–270. Kowalski, T., Holdenrieder, O., 2008. Eine neue Pilzkrankheit an Esche in Europa. Schw. Z. Forstw. 159, 45–50. Kowalski, T., Holdenrieder, O., 2009a. Pathogenicity of Chalara fraxinea. For. Path. 39, 1–7. Kowalski, T., Holdenrieder, O., 2009b. The teleomorph of Chalara fraxinea, the causal agent of ash dieback. For. Path. 39, 304–308. Kreamer, R., Kirby, K., 1994. India’s horticultural industry and the competition outlook in world markets. World Horticult. Trade & US Export Opport. 5, 8–14. Krehan, H., 2008. Asian Longhorn Beetle Anoplophora glabripennis (ALB) – eradication program in Braunau (Austria) in 2007. Forstschutz Aktuell 44, 27–29. Kriel, W.M., Swart, W.J., Crous, P.W., 2000. Foliar endophytes and their interactions with host plants, with speciﬁc reference to the Gymnospermae. Adv. Bot. Res. 33, 1–34. La Malfa, G., Bianco, V.V., 2006. Agrobiodiversità nel settore orticolo: espressioni e nuove esigenze. Atti del VII Convegno Nazionale sulla Biodiversità. Italus Hortus 13 (2), 31–44. Labaste, P., 2007. The European horticulture market – opportunities for Sub-Saharan African exporters. World Bank Working Papers, vol. 63, 113 pp. Lane, C.R., Hobden, E., Walker, L., Barton, V.C., Inman, A.J., Hughes, K.J.D., Swan, H., Colyer, A., Barker, I., 2007. Evaluation of a rapid diagnostic ﬁeld test kit for identiﬁcation of Phytophthora species, including P. ramorum and P. kernoviae at the point of inspection. Plant Path. 56, 828–835. Laudonia, S., Viggiani, G., 2005. Estese infestazioni di un tripide sui ﬁcus in Campania. Informatore Agrario 61, 73–74. Lawson, R.H., 1996. Economic importance and trends in ornamental horticulture. Acta Hort. 432, 226–237. Lehtimaki, S., 2002. The impact of EU enlargement on Finnish horticulture: the cases of Poland, Hungary and Estonia. In: Proc. 66th Eur. Sem. Eur. Assoc. Agr. Econ. (EAAE), Tallinn, Estonia, 20–22 May 1999, pp. 74–83. Letode, O., 2005. Luttes collectives: enjeux phytosanitaires et cadre reglementaire. Phytoma 580, 14–16. Levasseur, V., Pasquini, M.W., Kouame, C., Temple, L., 2007. A review of urban and peri-urban vegetable production in West Africa. Acta Hort. 762, 245–252. Levine, J.M., D’Antonio, C., 2003. Forecasting biological invasions with increasing international trade. Conserv. Biol. 17, 322–326. Linderholm, H.W., 2006. Growing season changes in the last century. Agric. Forest Meteor. 137, 1–14. Lockwood, J.L., Cassey, P., Blackburn, T.M., 2009. The more you introduce the more you get: the role of colonization pressure and propagule pressure in invasion ecology. Divers. Distrib. 15, 904–910. Loebenstein, G., 2006. Floriculture in Israel – closely linked to plant virus research. Acta Hortic. 722, 31–36. López-Moya, J.J., Fernández-Fernández, M.R., Cambra, M., García, J.A., 2000. Biotechnological aspects of plum pox virus. J. Biotech. 76, 121–136. Lotti, A., 2010. The commoditization of products and taste: slow food and the conservation of agrobiodiversity. Agric. Human Values 27, 71–83. Lozzia, G.C., 1983. Otiorrhynchus sulcatus nelle coltivazioni ﬂoricole del Lago Maggiore. Informatore Fitopatologico 33, 15–19. Luedeling, E., Blanke, M., Gebauer, J., 2009. Auswirkungen des Klimawandels auf die Verfügbarkeit von Kältewirkung (Chilling) für Obstgehölze in Deutschland. Erwerbs-Obstbau 51, 81–94. Lumpkin, T.A., 2007. Energizing global horticultural research for the developing world. Acta Hort. 759, 15–28. Lunati, F., 2007. L’ombra dell’Olanda sul futuro della ﬂoricultura italiana. Informatore Fitopatologico 57 (7–8), 3–6. MacLeod, A., Pautasso, M., Jeger, M.J., Haines-Young, R. Evolution of the international regulation of plant pests and challenges for future plant health. Food Security, doi:10.1007/s12571-010-0054-7, in press. MacRae, R.J., Frick, B., Martin, R.C., 2007. Economic and social impacts of organic production systems. Can. J. Plant Sci. 87, 1037–1044. Maekawa, T., 1996. The Japanese seed industry. In: Chominot, A., Daviron, B., Groffon, M. (Eds.), Globalisation des Economies Agricoles et Alimentaires: Situation et Prospective. Economie Rurale (No. 234–235), pp. 109–111. Mahmuti, M., West, J.S., Watts, J., Gladders, P., Fitt, B.D.L., 2009. Controlling crop disease contributes to both food security and climate change mitigation. Int. J. Agr. Sust. 7, 189–202. Maloba, K., Mosha, P., Otim, F.A., Kunda, M., 2008. Poor conditions for women working in African horticulture. Pesticides News 80, 20–22. Mann, L., Thompson, L., 2006. Change in Australian horticulture: the industry development ofﬁcer manager network. Acta Hort. 724, 329–333. Mannon, S.E., 2005. Risk takers, risk makers: small farmers and non-traditional agroexports in Kenya and Costa Rica. Hum. Organ. 64, 16–27. Martensson, A., 2007. Need for protective measures to combat potential outbreaks of Homalodiscia coagulata and Pierce’s disease in European viticulture. Acta Agric. Scand. B 57, 1–9. Mascheretti, S., Croucher, P.J.P., Kozanitas, M., Baker, L., Garbelotto, M., 2009. Genetic epidemiology of the Sudden Oak Death pathogen Phytophthora ramorum in California. Mol. Ecol. 18, 4577–4590.

13

Masumoto, M., Takahashi, G., Kawai, T., Kazushige, M., Oda, Y., Hayase, T., 2005. Additional list of thrips (Thysanoptera) intercepted at Japanese plant quarantine. Res. Bull. Plant Prot. Serv. Japan 41, 75–78. Mathe, A., Mathe, I., 2008. Quality assurance of cultivated and gathered medicinal plants. Acta Hort. 765, 67–75. McCullough, D.G., Work, T.T., Cavey, J.F., Liebhold, A.M., Marshall, D., 2006. Interceptions of non-indigenous plant pests at US ports of entry and border crossings over a 17-year period. Biol. Inv. 8, 611–630. McRae, C.F., Wilson, D., 2002. Plant health as a trade policy issue. Australas. Plant Path. 31, 103–105. Meilke, K., Van Duren, E., 1996. The North American free trade agreement and the Canadian agri-food sector. Can. J. Agr. Econ. 44, 19–37. Menini, U.G., 1987. FAO and horticultural research. Acta Hort. 211, 49–51. Miccolis, V., 2009. Calano le superﬁci orticole ma le produzioni restano stabili. Informatore Agrario 65, 55–59. Miller, S.A., Beed, F.D., Harmon, C.L., 2009. Plant disease diagnostic capabilities and networks. Annu. Rev. Phytopathol. 47, 15–38. Miranda, O., 1999. Modern technology, traditional relations: productive restructuring and seasonal work, in the fruit growing industry of northern Patagonia. Desar. Econ. – Rev. Cienc. Soc. 39 (153), 103–126. Mohanan, C., 2009. Bacterial diseases of teak (Tectona grandis L.f.) in forest nurseries and plantations in Kerala and their management. Indian J. Forestry 32, 131–136. Mondelaers, K., Aertsens, J., Van Huylenbroeck, G., 2009. A meta-analysis of the differences in environmental impacts between organic and conventional farming. Brit. Food J. 111, 1098–1119. Montanari, V., Trentini, L., 1996. Le principali avversità delle piante da orto in vivaio. Informatore Agrario Suppl. 52, 87–93. Montigaud, J.C., 1978. Economic policy and dynamics in the horticultural industry. Acta Hort. 55, 41–45. Montri, N., Wattananpreechanon, E., 2007. Soilless culture in Thailand. Acta Hort. 759, 187–193. Moorhouse, E.R., Charnley, A.K., Gillespie, A.T., 1992. A review of the biology and control of the vine weevil, Otiorhynchus sulcatus (Coleoptera: Curculionidae). Ann. Appl. Biol. 121, 431–454. Moralejo, E., Pérez-Sierra, A.M., Alvarez, L.A., Belbahri, L., Lefort, F., Descals, E., 2008. Multiple alien Phytophthora taxa discovered on diseased ornamental plants in Spain. Plant Path. 58, 100–110. Morse, J.G., Hoddle, M.S., 2006. Invasion biology of thrips. Ann. Rev. Entom. 51, 67–89. Moslonka-Lefebvre, M., Pautasso, M., Jeger, M.J., 2009. Disease spread in small-size directed networks: epidemic threshold, correlation between links to and from nodes, and clustering. J. Theor. Biol. 260, 402–411. Moustier, P., 2007. Urban horticulture in Africa and Asia, an efﬁcient corner food supplier. Acta Hort. 762, 145–158. Mulazzani, L., Malorgio, G., 2009. Market dynamics and commercial ﬂows in the Mediterranean area: triangular effects among the EU, the MPCs and Italy in the fruit and vegetable sector. New Medit. 8, 37–45. Mulder, A., 1989. Developments in ﬂower marketing. Fourth International Symposium on post-harvest physiology of ornamental plants, Herzliya, Israel, March 20–25, 1988. Acta Hort. 261, 319–326. Mumford, J.D., 2002. Economic issues related to quarantine in international trade. Eur. Rev. Agr. Econ. 29, 329–348. Murphy, D.J., 2007. Improving containment strategies in biopharming. Plant Biotech. J. 5 (5), 555–569. Mwebaze, P., Monaghan, J., Spence, N., MacLeod, A., Hare, M., Revell, B., 2010. Modelling the risks associated with the increased importation of fresh produce from emerging supply sources outside the EU to the UK. J. Agr. Econ. 61, 97–121. Nerelius, J., 2002. Den svenska tradgardsnaringens framtid [The future of the Swedish horticultural sector]. Sveriges Utsadesforenings Tidskrift 112 (4), 134–136. Neubauer, C., Gliessman, J., Beltz, H., 2006. Zu den Ausbreitungswegen von Phytophthora ramorum an Rhododendron und Viburnum auf Container-Stellﬂächen. Gesunde Pﬂanzen 58, 185–191. Neven, D., Reardon, T., 2004. The rise of Kenyan supermarkets and the evolution of their horticulture product procurement systems. Develop. Policy Rev. 22 (6), 669–699. Neven, D., Makokha Odera, M., Reardon, T., Wang, H., 2009. Kenyan supermarkets, emerging middle-class horticultural farmers, and employment impacts on the rural poor. World Dev. 37, 1802–1811. Nickle, D.A., 2003. A checklist of commonly intercepted thrips (Thysanoptera) from Europe, the Mediterranean, and Africa at US ports-of-entry (1983–1999). Part 1. Key to genera. Proc. Entom. Soc. Washington 105, 80–99. Nickle, D.A., 2008. Commonly intercepted thrips at US ports-of-entry from Africa, Europe, and the Mediterranean. III. The genus Thrips Linnaeus, 1758 (Thysanoptera: Thripidae). Proc. Entom. Soc. Washington 110, 165–185. Noble, R., Elphinstone, J.G., Sansford, C.E., Budge, G.E., Henry, C.M., 2009. Management of plant health risks associated with processing of plant-based wastes: a review. Bioresour. Technol. 100, 3431–3446. Norman, J.C., 2003. The horticultural industry in tropical Africa. Acta Hort. 621, 69–79. Nuez, F., Llacer, G., Ruiz, J.J., 2002. Horticulture in Spain. Chron. Hort. 42 (2), 25–29. Nzomoi, J.N., Byaruhanga, J.K., Maritim, H.K., Omboto, P.I., 2007. Determinants of technology adoption in the production of horticultural export produce in Kenya. Afr. J. Busin. Manag. 1, 129–135. Oda, M., 2007. Vegetable seedling grafting in Japan. Acta Hort. 759, 175–180.

14

K. Dehnen-Schmutz et al. / Scientia Horticulturae 125 (2010) 1–15

Odenstad, G., Holmstrom, S., 1975. Energiprisets inverkan pa jordbrukets produktionskostnader [Inﬂuence of energy prices on costs of production in agriculture in Sweden and some other West European countries]. Meddelande fran Jordbrukets Utredningsinstitut No. 2, 55 pp. Öktem, H.A., 2006. Plant biotechnology in Turkey. Acta Hort. 725, 73–79. Ogier, J., 1996. Horticulture – a century of change and progress in Guernsey. Acta Hort. 429, 547–552. Ogris, N., Hauptman, T., Jurc, D., 2009. Chalara fraxinea causing common ash dieback newly reported in Slovenia. Plant Path. 58, 1173. Ogris, N., Hauptman, T., Jurc, D., Floreancig, V., Marsich, F., Montecchio, L., 2010. First report of Chalara fraxinea on common ash in Italy. Plant Dis. 94, 133. Olivier, C.Y., Lowery, D.T., Stobbs, L.W., 2009. Phytoplasma diseases and their relationships with insect and plant hosts in Canadian horticultural and ﬁeld crops. Canad. Entom. 141, 425–462. Olper, A., Raimondi, V., 2008. Explaining national border effects in the QUAD food trade. J. Agr. Econ. 59, 436–462. Olympios, C.M., 2002. Vegetables in Greece: present situation and perspectives. Acta Hortic. 579, 31–36. Onistschenko, A., 1981. Trends in improving the organization of the USSR agroindustrial sector. Int. Z. Landwirtsch. 3, 231–235. Pagowska, E., Lipa, J.J., 2008. Voluntary codes of conduct as means limiting the spread of invasive alien species and quarantine pests. Prog. Plant Prot. 48, 47–51. Parikka, P., Lemmetty, A., 2009. Plant diseases in changing northern climatic conditions. Acta Hort. 838, 123–128. Park, K.S., McLaughlin, E.W., 2000. The US wholesale produce industry: structure, operations and competition. Acta Hort. 524, 197–204. Parrot, L., Dongmo, C., Ndoubme, M., Poubom, C., 2008. Horticulture, livelihoods, and urban transition in Africa: evidence from South-West Cameroon. Agr. Econ. 39, 245–256. Pautasso, M., Jeger, M.J., 2008. Epidemic threshold and network structure: the interplay of probability of transmission and of persistence in small-size directed networks. Ecol. Compl. 5, 1–8. Pautasso, M., Holdenrieder, O., Stenlid, J., 2005. Susceptibility to fungal pathogens of forests differing in tree diversity. In: Scherer-Lorenzen, M., Koerner, Ch., Schulze, E.D. (Eds.), Forest Diversity and Function. Springer, Berlin, pp. 263–289. Pautasso, M., Dehnen-Schmutz, K., Holdenrieder, O., Pietravalle, S., Salama, N., Jeger, M.J., Lange, E., Hehl-Lange, S., 2010. Plant health and global change – some implications for landscape management. Biol. Rev., doi:10.1111/j.1469185X.2010.00123.x, in press. Peck, J.E., Moldenke, A.R., 2010. Identifying pathways of biological invasion: can commercial moss harbor potential stowaways? Biol. Inv., doi:10.1007/s10530010-9686-y, in press. Pelikan, J., 1991. The Cuban-laurel thrips (Gynaikothrips ﬁcorum Marchal, 1908) in greenhouses in Czechoslovakia. Ochrana Rostlin 27, 287–291. Pemberton, R.W., Liu, H., 2009. Marketing time predicts naturalization of horticultural plants. Ecology 90, 69–80. Perez, A., 1998. The role of trade in US horticulture. Fruit Tree Nuts Situation Outlook Rep. 282, 22–27. Perrings, C., Dehnen-Schmutz, K., Touza, J., Williamson, M., 2005. How to manage biological invasions under globalization. Trends Ecol. Evol. 20, 212–215. Petit-Jean, M.F., 2008. Codes de bonnes pratiques en horticulture ornementale. PHM Revue Horticole 498, 21–24. Pickett Pottorff, L., Panter, K.L., 2009. Integrated pest management and biological control in high tunnel production. HortTechnology 19, 61–65. Piel, F., Gilbert, M., De Cannière, C., Gregoire, J.-C., 2008. Coniferous round wood imports from Russia and Baltic countries to Belgium. A pathway analysis for assessing risks of exotic pest insect introductions. Divers. Distrib. 14, 318–328. Pizarro Yanez, R., 2007. Chile, horticultura en el ﬁn del mundo. Horticultura Internacional 14 (59), 10–25. Prain, G., Arce, B., Karanja, N., 2007. Horticulture in urban eco-systems: some socioeconomic and environmental lessons from studies in three developing regions. Acta Hort. 762, 227–244. Pretty, J., 2008. Agricultural sustainability: concepts, principles and evidence. Phil. Trans. R. Soc. 363, 447–465. Primack, R.B., Higuchi, H., Miller-Rushing, A.J., 2009. The impact of climate change on cherry trees and other species in Japan. Biol. Cons. 142, 1943–1949. Primack, R.B., Miller-Rushing, A.J., 2009. The role of botanical gardens in climate change research. New Phytol. 182, 303–313. Prospero, S., Grunwald, N.J., Winton, L.M., Hansen, E.M., 2009. Migration patterns of the emerging plant pathogen Phytophthora ramorum on the West Coast of the United States of America. Phytopathology 99, 739–749. Qiu, H.J., Zhang, F.S., Zhu, W.B., Wang, H.B., Cheng, X., 2008. Reorientation of China’s agriculture over the next two decades. Outlook Agric. 37, 247–254. Rae, A.N., 2004. International trade in fruits and vegetables: barriers to trade, WTO proposals for reform and modelling alternative outcomes. Acta Hort. 655, 429–438. Raviv, M., 2010. Sustainability of organic horticulture. Hortic. Rev. 36, 289–333. Rayment, G.E., 2006. Australian efforts to prevent the accidental movement of pests and diseases in soil and plant samples. Comm. Soil Sci. Plant Anal. 37, 2107–2117. Reganold, J.P., Glover, J.D., Andrews, P.K., Hinman, H.R., 2001. Sustainability of three apple production systems. Nature 410, 926–930. Reichard, S.H., White, P., 2001. Horticulture as a pathway of invasive plant introductions in the United States. BioScience 51, 103–113. Reinert, J.A., 1983. Controlling Cuban laurel thrips in nurseries and landscapes. Am. Nurseryman 157, 63–66.

Renwick, A., 2000. Economic Results of Horticulture in the East and South East of England, pp. 43. Riedel, B., Bokelmann, W., Canavari, M., 2009. Regional competitiveness of fresh vegetable production in Europe: a cluster and value chain perspective. Acta Hort. 831, 147–152. Rodoni, B., 2009. The role of plant biosecurity in preventing and controlling emerging plant virus disease epidemics. Virus Res. 141, 150–157. Roques, A., Auger-Rozenberg, M.A., 2006. Tentative analysis of the interceptions of non-indigenous organisms in Europe during 1995–2004. Bull. OEPP 36, 490–496. Rossman, A., 2009. The impact of invasive fungi on agricultural ecosystems in the United States. Biol. Invas. 11, 97–107. Rothenburger, W., 1973. Zukünftige Strukturveränderungen im Gartenbau. Gartenbauwissenschaft 38, 455–478. Rothenburger, W., 1987. How can we improve the environmental and economic value of horticulture? Acta Hort. 203, 331–342. Salinari, F., Rettori, A., Gullino, M.L., 2004. Inﬂuenza dei cambiamenti climatici sulle ﬁtopatie. Informatore Fitopatologico 54, 27–33. Schmidt, E., 1996. The German market for ﬂoricultural products: an industrial economics’ approach. In: Brumﬁeld, R.G. (Ed.), XIII Int. Symp. Hort. Econ., vol. 429, Aug 4–9, 1996, Rutgers, New Brunswick, NJ, pp. 295–300. Scholthof, K.B.G., 2007. The disease triangle: pathogens, the environment and society. Nature Rev. Microb. 5, 152–156. Schumacher, J., Heydeck, P., Leonhard, S., Wulf, A., 2007a. Neuartige Schaden an Eschen: Ursachen und Situation in Deutschland. Allg. Forst. Z. Waldwirt. Umweltv. 62 (20), 1–3. Schumacher, J., Wulf, A., Leonhard, S., 2007b. Erster Nachweis von Chalara fraxinea T. Kowalski sp. nov. in Deutschland - ein Verursacher neuartiger Schaden an Eschen. Nachrichtenblatt des Deutschen Pﬂanzenschutzdienstes 59, 121–123. Schwentesius, R., Gomez, M.A., 2002. Supermarkets in Mexico: impacts on horticulture systems. Develop. Pol. Rev. 20, 487–502. Seem, R.C., 2009. Sensors and other nanotechnologies for plant epidemiological studies and disease management systems. In: Gadoury, D.M, Seem, R.C., Moyer, M.M., Fry, W.E. (Eds.), Proc. 10th Int. Epid. Workshop, Geneva, NY, USA, pp. 146–147. Sen, A., 1991. Public action to remedy hunger. Interdisc. Sci. Rev. 16, 324–336. Serrurier, M., 2009a. Le commerce des légumes frais: période de 1997 à 2007. InfosCtiﬂ 251, 20–27. Serrurier, M., 2009b. Le commerce extérieur franc¸ais des fruits frais: période de 1997 à 2007. Infos-Ctiﬂ 250, 14–21. Shefﬁeld, S.S., 1996. The horticulture sector of the former Soviet Union. Acta Hort. 429, 21–33. Shivas, R.G., Beasley, D.R., Pascoe, I.G., Cunnington, J.H., Cunnington, Pitkethley, R.N., Priest, M.J., 2006. Specimen-based databases of Australian plant pathogens: past, present and future. Australas. Plant Path. 35, 195–198. Shtienberg, D., 2007. The contribution of epidemiological research to plant disease management. Australas. Plant Path. 36, 510–515. Shumeiko, A.I., 1984. Forecasting development and improvement of territorial organization of horticulture in the Ukrainian SSR. Visnik Sil’s’kogospodars’koi Nauki 1, 11–15. Simberloff, D., 2009. The role of propagule pressure in biological invasions. Ann. Rev. Ecol. Evol. Syst. 40, 81–102. Skarpaas, O., Okland, B., 2009. Timber import and the risk of forest pest introductions. J. Appl. Ecol. 46, 55–63. Skottrup, P.D., Nicolaisen, M., Justesen, A.F., 2008. Towards on-site pathogen detection using antibody-based sensors. Biosens. Bioelect. 24, 339–348. Smith, R.M., Baker, R.H.A., Malumphy, C.P., Hockland, S., Hammon, R.P., Starzewski, J.C., Collins, D.W., 2007. Recent non-native invertebrate plant pest establishments in Great Britain: origins, pathways, and trends. Agr. For. Entom. 9, 307–326. Stanosz, G.R., Blodgett, J.T., Smith, D.R., Kruger, E.L., 2001. Water stress and Sphaeropsis sapinea as a latent pathogen of red pine seedlings. New Phytol. 149, 531–538. Steffen, K., 1992. Italy’s horticulture facing the single market: how a young business will grow big with small plants. Gartnerborse und Gartenwelt 92, 1834–1836. Steinborn, P., Bokelmann, W., 2007. Aktuelle Strukturen des Obstbaus in Deutschland. Erwerbs-Obstbau 49, 115–125. Stephenson, B.P., Gill, G.S.C., Randall, J.L., Wilson, J.A., 2003. Biosecurity approaches to surveillance and response for new plant pest species. N. Z. Plant Prot. 56, 5–9. Steta, M., 2004. Mexico as the new major player in the vegetable greenhouse industry. Acta Hort. 659, 31–36. Stockdale, E.A., Lampkin, N.H., Hovi, M., Keatinge, R., Lennartsson, E.K.M., Macdonald, D.W., Padel, S., Tattersall, F.H., Wolfe, M.S., Watson, C.A., 2001. Agronomic and environmental implications of organic farming systems. Adv. Agron. 70, 261–327. Storck, H., 1984. Structural changes in German horticulture during the last decade. Acta Hort. 155, 335–342. Suri, M., Huld, T.A., Dunlop, E.D., Ossenbrink, H.A., 2007. Potential of solar electricity generation in the European Union member states and candidate countries. Solar Energy 81, 1295–1305. Surkov, I.V., Lansink, A.G.J.M.O., Van der Werf, W., Van Kooten, O., 2007. Designing optimal phytosanitary inspection policy – A conceptual framework and an application. In: Lansink, A.G.J.M.O. (Ed.), New Approaches to the Economics of Plant Health. Wageningen, the Netherlands, pp. 39–54. Surkov, I.V., Lansink, A.G.J.M.O., van der Werf, W., 2009. The optimal amount and allocation of sampling effort for plant health inspection. Eur. Rev. Agr. Econ. 36, 295–320.

K. Dehnen-Schmutz et al. / Scientia Horticulturae 125 (2010) 1–15 Surkov, I.V., Lansink, A.G.J.M.O., van Kooten, O., van der Werf, W., 2008a. A model of optimal import phytosanitary inspection under capacity constraint. Agric. Econ. 38, 363–373. Surkov, IV., van der Werf, W., van Kooten, O., Lansink, A.G.J.M.O., 2008b. Modeling the rejection probability in plant imports. Phytopathology 98, 728–735. Suslow, K., 2008a. Determining the effectiveness of the federal order/interim rule on Phytophthora ramorum dissemination in nurseries. In: Frankel, S.J., Kliejunas, J.T., Palmieri, K.M. (Eds.), Proc. 3rd Sudden Oak Death Science Symposium. GTR-214, USDA FS, pp. 27–30. Suslow, K., 2008b. Recommended industry best management practices for the prevention of Phytophthora ramorum introduction in nursery operations. In: Frankel, S.J., Kliejunas, J.T., Palmieri, K.M. (Eds.), Proc. 3rd Sudden Oak Death Science Symposium. GTR-214, USDA FS, pp. 115–128. Sutherst, R.W., Collyer, B.S., Yonow, T., 2000. The vulnerability of Australian horticulture to the Queensland fruit ﬂy, Bactrocera (Dacus) tryoni, under climate change. Austr. J. Agr. Res. 51, 467–480. Szabo, I., 2009. First report of Chalara fraxinea affecting common ash in Hungary. Plant Path. 58, 797. Takahashi, N., Ito, M., 2005. Detection and eradication of the Asian longhorned beetle in Yokohama. Japan. Res. Bull. Plant Prot. Serv. Japan 41, 83–85. Talgø, V., 2009. Diseases and disorders on ﬁr (Abies spp.) grown as Christmas trees, boughs, and landscape plants in Norway; from seed to site. Ph.D. thesis, Norwegian University of Life Sciences, Department of Plant and Environmental ˘ Norway. Sciences, As, Talgø, V., Sletten, A., Brurberg, M.B., Solheim, H., Stensvand, A., 2009. Chalara fraxinea isolated from diseased ash in Norway. Plant Dis. 93, 548. Thompson, M., Kirby, K., 1994. Australia’s horticultural industry and the competition outlook in world markets. World Hort. Trade & US Export Opport. 4, 12–24. Thorne, F., Kelley, P.W., Maher, M., Harte, L., 2002. A comparative assessment of the competitiveness and cost structures of hardy nursery stock production in Ireland, the Netherlands and the UK. Farm Manag. 11, 269–278. Timmons, F.L., 2005. A history of weed control in the United States and Canada. Weed Sci. 53, 748–761. Tombolato, A.F.C., 2006. Genetic resources and breeding ornamentals in Brazil. Acta Hort. 714, 13–20. Tomiczek, C., Hoyer-Tomiczek, U., 2007. Der Asiatische Laubholzbockkafer (Anoplophora glabripennis) und der Citrusbockkafer (Anoplophora chinensis) in Europa – ein Situationsbericht. Forstschutz Aktuell 38, 2–5. ˜ P., Doka, D., Becker, H., 2008. Die Wildsammlung von Arznei- und Torres-Londono, Gewürzpﬂanzen in Albanien, untersucht an Beispielen aus dem Umland von Peshkopi (Region Dibër). Zeitschrift für Arznei und Gewüzpﬂanzen 13, 153–160. Tscharntke, T., Bommarco, R., Clough, Y., Crist, T.O., Kleijn, D., Rand, T.A., Tylianakis, J.M., Van Nouhuys, S., Vidal, S., 2007. Conservation biological control and enemy diversity on a landscape scale. Biol. Control 43, 294–309. Tuovinen, T., 2009. Risk of invasive arthropod pests related to climate change in the northernmost small fruit production area in EU. Acta Hort. 838, 151–154. Tyson, R.V., Hochmuth, R.C., Lamb, E.M., Hochmuth, G.J., Sweat, M.S., 2001. A decade of change in Florida’s greenhouse vegetable industry: 1991–2001. Proc. Florida Hort. Soc. 114, 280–283. Vacante, V., Bonsignore, C.P., 2009. Problemi emergenti provocati da insetti e acari dell’Italia meridionale. Protezione delle Colture 4, 25–31. Van der Gaag, D.J., Scholte, E.J., 2007. Anoplophora: een bedreiging voor Nederlandse loofbomen. Gewasbecherming 38, 37–41. Van der Lans, C., Beerling, E., Ramakers, P., 2008. Plant health in innovative growing systems. Bull. OILB/SROP 32, 219–225. van der Putten, W.H., Klironomos, J.N., Wardle, D.A., 2007. Microbial ecology of biological invasions. ISME J. 1, 28–37. van der Velden, N.J.A., Janse, J., Kaarsemaker, R.C., Maaswinkel, R.H.M., 2004. Sustainability of greenhouse fruit vegetables: Spain versus the Netherlands; development of a monitoring system. Acta Hort. 655, 275–281. Van Kleunen, M., Johnson, S.D., Fischer, M., 2007. Predicting naturalization of southern African Iridaceae in other regions. J. Appl. Ecol. 44, 294–306.

15

Van Kooten, O., Heuvelink, E., Stanghellini, C., 2008. New developments in greenhouse technology can mitigate the water shortage problem of the 21(st) century. Acta Hort. 767, 45–51. Van Oosten, H.J., 1998. Horticultural research in the Netherlands: changes and challenges for 2010. NRLO Rapport 98/26E, 29 pp. Van Oosten, H.J., 1999. Horticultural research in the Netherlands: changes and challenges for 2010. Acta Hort. 495, 427–437. van Schaik, M., 2008. De wereldappelproductie blijft stijgen. [The world apple production continues to grow]. Fruitteelt (Den Haag) 98, 14–15. Vercauteren, A., De Dobbelaere, I., Grünwald, N.J., Bonants, P., Van Bockstaele, E., Maes, M., Heungens, K., 2010. Clonal expansion of the Belgian Phytophthora ramorum populations based on new microsatellite markers. Mol. Ecol. 19, 92–107. Victor, A.-S., 2007. The dynamics of horticultural export value chains on the livelihood of small farm households in Southern Ghana. Afr. J. Agr. Res. 2, 435–440. Vierbergen, G., 2001. Thrips palmi: pathways and possibilities for spread. Bull. OEPP 31, 169–171. Viljanen-Rollinson, S.L.H., Cromey, M.G., 2002. Pathways of entry and spread of rust pathogens: implications for New Zealand’s biosecurity. N. Z. Plant Prot. 55, 42–48. Voskuilen, M.J., 1989. Leidschendam-Nootdorp-agriculture and horticulture in a redevelopment. Mededelingen-Landbouw-Economisch Instituut (No. 411), 82 pp. Vox, G., Schettini, E., Cervone, A.L., Anifantis, A., 2008. Solar thermal collectors for greenhouse heating. Acta Hort. 801, 787–794. Waage, J.K., Woodhall, J.W., Bishop, S.J., Smith, J.J., Jones, D.R., Spence, N.J., 2008. Patterns of plant pest introductions in Europe and Africa. Agr. Syst. 99, 1–5. Wand, S.J.E., Steyn, W.J., Theron, K.I., 2008. Vulnerability and impact of climate change on pear production in South Africa. Acta Hort. 800, 263–271. Wang, Y., Wu, D., 2007. The impact of ﬂower certiﬁcation on the development of Chinese ﬂoral industry. Forest Res., Beijing 20, 763–767. Warrington, I.J., Wallace, B.D., Scarrow, D., 2004. International perspectives in horticultural extension – a New Zealand viewpoint. Horttechnology 14, 20–23. Warrington, I., 2005. Building bridges and enhancing economic potential. Acta Hort. 694, 215–221. Webb, K.M., Ona, I., Bai, J., Garrett, K.A., Mew, T., Cruz, C.M.V., Leach, J.E., 2010. A beneﬁt of high temperature: increased effectiveness of a rice bacterial blight disease resistance gene. New Phytol. 185, 568–576. Wermund, U., Wainwright, H., 2000. Determining inﬂuencing factors of Hardy Ornamental Nursery Stock (HONS) sales. In: De Groot, N.S.P., De Kleijn, E.H.J., Csizinksy, A.A., Weerts, J. (Eds.), Proc. XXV Int. Hort. Cong., Aug 2–7, 1998, Brussels, Belgium, PT14, 524, pp. 73–79. Werres, S., Wagner, S., Brand, T., Kaminski, K., Seipp, D., 2007. Survival of Phytophthora ramorum in recirculating irrigation water and subsequent infection of Rhododendron and Viburnum. Plant Dis. 91, 1034–1044. Xu, X.M., Harwood, T.D., Pautasso, M., Jeger, M.J., 2009. Spatio-temporal analysis of an invasive plant pathogen (Phytophthora ramorum) in England and Wales. Ecography 32, 504–516. Xue, L., Revell, B.J., 2009. Which way forward for China’s vegetable exports? Brit. Food J. 111, 26–43. Yachi, S., Loreau, M., 1999. Biodiversity and ecosystem productivity in a ﬂuctuating environment: the insurance hypothesis. Proc. Nat. Acad. Sci. USA 96, 1463–1468. Yang, S.D., Long, M.H., Tang, Z.P., Huang, G.X., Egashira, K., 2008. Present status with some constraints and future development in the horticultural industry of Guangxi province China. J. Faculty Agr. Kyushu Univ. 53, 127–131. Zapata, M., Cortina, J., 1984. Horticultural structure of Murcia and the Spanish adhesion to E.E.C. Acta Hort. 155, 41–45. Zeng, Q.Y., Hansson, P., Wang, X.R., 2005. Speciﬁc and sensitive detection of the conifer pathogen Gremmeniella abietina by nested PCR. BMC Microbiol. 5, 65. Zürcher, M., Siegfried, W., Sacchelli, M., Hohn, H., Husistein, A., Bertschinger, L., 2003. Systemvergleichsversuch: integrierte und biologische Apfelproduktion. Teil I: Pﬂanzenschutz. Obst- und Weinbau 139 (21), 9–13.

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