Ruminant Nutrition Notes Extension Animal Husbandry Department of Animal Science North Carolina State University Drought and Flood Recovery: Part 2 Renovating Cool-Season Pastures Dr. Matt Poore NCSU Animal Science Many producers in the Piedmont and Mountains of North and South Carolina had long-term pasture damage due to hot dry weather last summer and fall. In the Coastal Plain, many producers with cool season pastures in a flood plain also suffered severe damage to stands due to prolonged flooding. Whatever caused the damage there are several things you should start doing now to ensure a successful pasture renovation. Site Assessment The first step in the renovation process is assessing the site and determining the extent of renovation that is needed. This could range from the use of a selective herbicide only, herbicide plus additional seeding, or a complete kill and replanting. There are two very important considerations in any of these systems. First, you should spend some time contemplating what caused the damage to the pasture in the first place. Well established cool-season perennials on adapted soils have a very long stand life, especially tall fescue, so often the stand failure is the result of overgrazing, soil fertility problems, or weed encroachment. Understanding the cause of the stand failure and developing an understanding of how management needs to change before renovating is a key to long-term success. Another critical piece of the site assessment is making sure that the physical layout of the farm will allow the careful management of the renovated pasture. It is critical to have enough crossfencing to allow very limited grazing of new stands, and it also is helpful to have the skills necessary to use temporary electric fence to further subdivide the renovated area, helping to reduce the chance of short grazing and to protect weak areas. Additionally, it is important to producers for understand that perennial pastures take several years to fully establish, so reducing stocking rate (or increasing days of hay feeding) on the farm will usually be necessary for successful establishment. Soil samples should be taken early in the process and a fertilizer/lime plan put into place. If soil pH is low then lime should be added as early as possible as it takes several months to start working. Low pH might be one of the reasons for losing the stand, and in that case it might take several years and applications of lime to reach a pH necessary for successful establishment. Phosphorus (P) and potassium (K) are both critical for vigorous growth of cool season perennial pastures. Most producers with cool season perennials also need to be using clovers, and they are especially sensitive to low soil nutrients and low pH.

Assessment of the plants present in the pasture is a critical step in determining how to proceed with the renovation. Determining the balance of desirable grasses, desirable legumes, and undesirable plants (weeds) will tell whether the pasture needs to be killed and completely renovated, or if a selective herbicide and rest will be sufficient for the stand to recover. The technique we usually employ for this is called the "Point Step" approach. To do this start by making a worksheet with columns for the plants you expect to find, and rows for each pasture to be assessed. If you don't know how to identify the plants you might need to take a reference book with you (like Southern Forages) or your extension agent or other knowledgeable advisor that can teach you to identify the species. For example in a tall fescue/clover pasture the main desirable grass species is tall fescue, but it might also include orchardgrass, bluegrass, dallisgrass or others. Also, you would expect to find white clover, and perhaps red clover. Weeds that are usually expected include annuals (e.g. buttercup, chickweed) and perennials (e.g. horsenettle, blackberry, hemp dogbane). If the assessment is done in spring then the winter annuals would be the major species found, but it is a good idea to make notes about evidence of the summer weeds mentioned (for example if horsenettle is a problem you will find the orange "berries" from the previous year). There will be a diversity of desirable and undesirable plants in most pastures, so have a category of "Other Desirable" and "Other Undesirable". Even if you can't positively identify all the species you can often can tell if they are desirable based on their morphology (spines? leafy? many stems?). Finally, put a column for "bare ground" which means no living plant is touched at that point. See the example of a simple Point-Step worksheet in this publication. To do the Point-Step assessment take the sheet on a clipboard and walk the pasture randomly just like you would take a soil sample. Assess a uniform area, again just like a soil sample, and time your point identification so that you mark at least 200 points in a pasture. Walk the number of steps you plan between each sampling point and on your last step identify the species that touches the tip of your shoe. Actually putting a mark on the end of your shoe will help you decide what species you are really stepping on. Make sure as you walk you make observations about issues with the pasture such as large bare areas, evidence of out-of-season weeds, and other issues that might need to be considered later. Once you cover the whole pasture, divide the number of each plant (or plant type) by the total points. This will give you a quantitative estimate of the stand of both desirable plants and the different weeds you will have to address. Again, if possible have someone with you that has experience with pasture renovation and plant identification. Figure 1. Point Step Worksheet Pasture #

1*

Tall Fescue

Orchard -grass

White Clover

Buttercup

Other Desirable

Other Undesirable

Bare Ground

IIII IIII IIII IIII IIII IIII IIII IIII IIII IIII 34

III

IIII IIII

IIII IIII IIII II

IIII

IIII

IIII IIII IIII 100 IIII IIII IIII IIII IIII 29

3

9

17

4

4

2 * Pasture 1 shows signs of heavy horsenettle and dog fennel population.

Total

The example given for Pasture 1 shows 100 total points, but keep in mind for most pastures a total of closer to 200 is better, with 100 being a minimum. Also, the total will not be an even number (100 or 200) so don't worry about that, just get the total. At the time of assessment this pasture had 50% of the points as desirable plants, 9% clover, 21% weeds, and 29% bare ground. This is probably the minimum number of points with a desirable plant for a pasture to be renovated with fertility management and herbicides. Another important bit of information about this example pasture is that the clover stand is low, so not that much will be sacrificed by using the selective herbicides. The high level of bare ground is especially problematic and probably shows a need for reduced grazing pressure. Herbicides will usually be necessary to clean up weed problems, regardless of the extent of renovation necessary. Use the composition of the weeds currently present to select the herbicide, and especially consider those summer weeds that might not be present now but that you saw evidence of. The example pasture has buttercup as the main weed at this point, but shows evidence of horsenettle and dog fennel. Dog fennel is an indicator of poor fertility and low pH, so keep that in mind. An application of 2-4 D now will control the buttercup without completely killing the white clover but will not have any residual effect on the summer weeds. A better choice might be Grazon Next HL in early summer, which would kill the clover (which is only 9% of the stand in this case), and give some control of other annual and perennial weeds during the coming growing season. If the butter cup has not bloomed yet, then an application of 2-4 D to take out the butter cup now, followed by a residual herbicide in early summer might be best. If the pasture is "weedy" (meaning more than 20% total weed points), especially if there are difficult to control perennial weeds, then a several year herbicide treatment would probably be prescribed. This might mean an initial treatment with glyphosate (RoundUp) if desirable species are low followed by several applications of Grazeon Next HL. Being aggressive with weed control to break up the weed cycle on these pastures will be key to long-term success. Renovation strategies Once you have assessed the pasture, a renovation strategy needs to be developed to reach your long-term goals. In fescue country, a major thing to consider is whether this might be an opportunity to convert toxic tall fescue to a non-toxic novel tall fescue or a warm-season grass. Fescue toxicosis causes many problems for cow-calf and growing cattle production, so don't miss an opportunity to kill a weak stand, plant it with a summer annual, and then back into an improved perennial. A key consideration, however, is that the novel fescue varieties or native warm seasons take a higher level of management to give optimal production. On many farms bermudagrass is an option, so keep it in mind as it is easier to manage than native warm seasons, although it does take a lot of nitrogen to thrive. It is a very rare situation where we would recommend Kentucky-31 infected fescue for the replant, so even if you feel there is only a need to overdrill the pasture, if it is toxic fescue seriously consider killing it and renovating into a non-toxic fescue or summer forage. As mentioned earlier the first step should always be to apply the fertilizer and lime. Your options then are to use a selective herbicide only, herbicide followed by fall drilling of grass over the existing stand, or killing with glyphosate, planting an annual and then following with a perennial. Eventually most producers will add clover to the stands, but that is generally more successful in the year following the grass establishment due to the very competitive nature of many of the new clover varieties that can hurt establishment of the grass. Also, allowing an extra year for

broadleaf weed control can be very helpful when weeds are present. In most environments here we recommend only planting cool-season grasses in the fall. So, if the stand is very thin with a lot of weeds, the best strategy is to kill the pasture with glyphosate and then plant a summer annual such as sorghum-sudan or millet. These summer annual grasses grow rapidly and form a dense canopy that smothers out weeds and toxic fescue seedlings that might sprout. Following the final harvest of the summer annual, spray glyphosate again and then plant the cool-season perennial. If there was a high population of weeds, or to increase the potential for elimination of toxic fescue seedlings, consider following the summer annual with a winter annual, then another summer annual, and finally plant the cool season perennial the second fall. Making the new planting successful There are many things to think about at the time of planting and during the following two years to make the new planting successful. First, remember that good pasture starts with good seed. Make sure seed is an improved variety adapted to your area. The best way to insure that you are planting the best species and variety is to talk to your extension agent and other advisors, other farmers and seed company representatives. If you have a large percentage of your farm in coolseason forages and have limited summer grazing, consider planting a warm-season grass; either bermudagrass, bahiagrass, or summer annuals. If you have plenty of warm-season grasses, then consider planting a non-toxic fescue, rescuegrass (Matua Brome or similar), orchardgrass, or a mixture of cool season species. When planting it is critical that you calibrate the drill and set the depth correctly for the species you are planting. It is possible to get a stand under the perfect conditions from broadcasting seed, especially for crabgrass, ryegrass and clovers, but in most cases we would recommend a no-till drill. Some farmers will chose to do tillage to kill weeds and incorporate lime and fertilizer, and in that case the seeding can be with a conventional grain drill, a Brilliion seeder or by broadcasting and running a cultipacker. For a number of reasons, most grass farmers have gone to a no-till drill for most of their cool season plantings. One of the biggest reasons for stand failure is too deep a planting depth, but most drills have a simple system for changing planting dapth. Drilling very small seeds (clover, crabgrass, etc.) too deep is very easy to do, given that they need to be planted no more than a 1/4-1/2 inch deep. Once the seeded forages start to emerge walk the field occasionally and scout for weeds. An early flush of broadleaf weeds such as buttercup, chickweed or henbit can really hurt the stand establishment, so keep an eye out for that and use appropriate herbicide to take those species out. Continue to monitor the stands and scout for pests that may be eating the seedlings (e.g. crickets). For most new seedings it is critical to stay off them until they develop a strong root system. Once they reach a grazable height you can flash graze them to remove tops, but don't graze them shorter than about 4 inches, and do everything you can to reduce cattle and vehicle traffic, feeding, etc. as these practices will damage the new plants. Often we recommend taking a hay cutting the first spring, but again don't cut too short, leaving a minimum of 4 inches of residue. Fertilize the crop as recommended and continue to treat it gently until the second year when you can graze it more aggressively.

Pasture renovation is sometimes needed due to an act of nature such as a flood or severe drought, but usually stand loss is a result of the environmental challenged coupled with mismanagement, including overgrazing, failure to control weeds and poor fertility management. A successful outcome will require paying attention to all the details discussed above, and a decision by the producer to improve the way they manage pasture. The process is time consuming, costly, and somewhat risky, but it can dramatically improve the specific pasture in question. Additionally, careful species and variety selection can also have a positive impact on the forage system if the plan is developed to improve the balance of cool and warm-season forages and to eliminate some toxic tall fescue.