Weed Control In Tall Fescue Pastures And Hayfields

 DR. CLYDE LANE JR.
KNOXVILLE, TENN.
   Weeds are one of the biggest problems in tall fescue pastures and hayfields. Buttercup, musk thistle, buckhorn plantain and horsenettle are just a few of the weeds that can move quickly into fields and cause production losses. There are several things that can be done to minimize the problems.
   Correct stand and soil fertility problems. Weeds move into fields because they are able to out-compete the existing plants. Thick, aggressive stands of tall fescue have little weed pressure. There is no space for a weed seed to germinate and grow. A strong stand of grass minimizes weed pressure. All the weeds can be killed this year, but if large portions of the ground remain bare, a new crop of weeds will germinate and grow. Be sure that poor soil fertility is not the reason for a poor stand. A soil test will provide the information needed for proper fertilization. Soil test and follow the recommendations. Once fertility problems are corrected, evaluate the stand of grass. If it is weak, consider replanting this fall.
   Identify the weeds. Before using herbicides, know the specific weeds that need to be killed. Certain weeds are more difficult to kill, so herbicides, application timings and rates may vary. If the name of a weed on the farm cannot be identified, take a sample to the local Extension office for help in identification and for specific herbicide recommendations.
   Spray at the appropriate time. Knowing whether a weed grows during the winter or summer is essential in knowing the proper time to spray with a herbicide. For winter weeds such as buttercup, musk thistle and buckhorn plantain, a herbicide should be sprayed during either December or March for adequate control. After two to three days of warm weather, the weed will be growing enough to take up the herbicide and be controlled.
   Some weeds, such as horsenettle, pigweed and cocklebur, only grow during the summer. They germinate and grow from May to October/November. The winter or spring application will not adequately control them, because they are not up yet. A late May or June herbicide application is needed for these weeds. Summer sprays are more difficult, mainly due to all of the sensitive crops that are around. Cotton, soybeans, tomatoes and tobacco can be severely damaged by drift from herbicides. Know the surrounding crops before using herbi- cides, particularly during the summer.
   Select the proper herbicide. There are many herbicides available. Be sure to use one that is labeled for pasture and hay. It is illegal to use any herbicide on pastures and hayfields that has not been tested and approved for use. Just because it works does not mean it is safe. Read and follow all label instructions when using herbicides.
   Many weeds can be controlled adequately with 2,4- D. Buttercup and musk thistle can be almost totally controlled with a 2-pints-per-acre application. If buckhorn or broadleaf plantain is present, increase the rate to 4 pints per acre. This higher rate will take out both red and white clover. If the application is made in December, clovers can be replanted in February/March.
   For weeds that are more difficult to control, particularly summer weeds such as horsenettle and tall ironweed, some new herbicides are available. Grazon P+D, Surmount and Pasture- Gard are examples of those available to kill more difficult weeds. Specific recommendations will depend on where your farm is, which weed you have, and other factors.
   Following these recommendations should help minimize weed growth and improve the yield and quality of pasture and hay. Δ DR. GARY BATES: Professor and Forage Agronomist, University of Tennessee
DR. CLYDE LANE JR.: Professor and Extension Beef Cattle Specialist, University of Tennessee