CROPS
Patience, time are the keys to tall fescue renovation
By Dr. Paul Tracy, MFA Director of Agronomy Tech Services
Before I discuss tall fescue renovation, I would like to acknowledge the University of Missouri Extension, Agricultural Crop Management Conference (formally Ag. Chem. Short Course). This event has traditionally been designed for agriculture businesses and university extension employees. As crop production becomes more technical, I believe producers should consider attending this course.
The meeting will have crop update sessions. In addition, there will be 10 concurrent sessions. Individuals can attend six of those sessions. Concurrent session titles are as follows: weed management issues; business management; forages; entomology issues; drainage, irrigation and water management; precision agriculture; interactions between insects, diseases and weeds; crop management for value-added traits; nutrient management; and alternative crops.
The conference is scheduled for Nov. 28-29, 2000. For meeting information, please contact Susan Brouk at 573-882-9552.
In mid-September, I attended the University of Missouri Southwest Center field day at Mount Vernon, Mo. At this field day, Craig Roberts, state extension forage specialist, discussed using novel (friendly) endophyte tall fescue to eliminate animal health problems associated with endophyte-infected tall fescue. I will discuss novel endophyte tall fescue in more detail in a future Today's Farmer. Roberts discussed the importance of eradicating all existing tall fescue before planting any crop (especially improved tall fescue) into that field.
There are several reasons for eradicating tall fescue. These include: establishing warm-season grasses for federal programs; establishing endophyte-free or novel endophyte tall fescue; establishing alternative, cool-season grasses like smooth brome, orchard or timothy; establishing wildlife-friendly or native crops. Whatever your reason, it is difficult to completely remove tall fescue from the environment.
Tall fescue renovation was popular 10 to 15 years ago when endophyte-free tall fescue was introduced. This interest has waned recently due to poor vigor and stress tolerance associated with endophyte-free tall fescue plants. Another reason for lost interest is the hypothesized encroachment or re-establishment of endophyte-infected tall fescue into renovated endophyte-free fields.
Roberts said the increase in endophyte-infected fescue into endophyte-free fields is not a result of the seed bank, seed dispersion or encroachment but rather a failure to completely kill all existing tall fescue from fields prior to re-establishment. I also believe many renovated fields were planted to endophyte-free fescue before complete elimination of the previous stand had occurred.
How have most producers removed tall fescue? Many have tried to accomplish this with a single herbicide application, usually Roundup in the fall or spring, followed by no-till re-seeding two to four weeks post herbicide application.
Some have tried a two-pass application consisting of Roundup in the fall, followed by Roundup or Gramoxone the following spring. Some have combined tillage and physical seedbed preparation into their renovation program.
Even though these herbicide programs look good initially, in most cases, the complete eradication of existing tall fescue has not occurred. An established tall fescue sod can look completely dead above ground but still be viable in the root/sod complex. With tall fescue being such a competitive grass species, any "missed" plants can become aggressive "weeds" regardless of which crop you have planted.
Time and patience are the keys to proper tall fescue eradication. Do not assume because all tall fescue leaves are dead that you have killed the stand. The only way to be sure no residual tall fescue is present is to conduct at least two herbicide applications or tillages with a substantial interval between applications.
The best way to manage a field during the interim is to maintain a crop canopy to prevent weed invasion and tall fescue regeneration. This is best done with a "smother" crop. If possible, row crops such as corn, soybeans and especially milo make good smother crops. Not only do they canopy quickly, but they can be used in combination with several labeled herbicides that have good tall fescue activity.
Two years of these row crops will do two things. First, all residual tall fescue should be removed during this time period. Second, this will give sufficient time to weaken the tall fescue seed bank. The seed-borne endophyte has a life expectancy of less than two years inside nongerminated tall fescue seed. Therefore, any residual seed in the tall fescue seed bank will not contain viable endophyte.
In fields not suited for row crops, annual forages like Marshall ryegrass, sudangrass, sorghum-sudan, pearl millet, wheat or triticale make excellent smother crops. They provide high-yielding forage. I suggest two cycles of these annual forages before reintroducing perennial grasses into an old tall fescue field.
The bottom line concerning tall fescue renovation is to use a combination of all strategies that are available. Be patient, and you can expect a long-term, successful tall fescue renovation project.