The Weed Doctor Tall Fescue - Another Perennial Weed Headache

By W. Carroll Johnson, III, Ph.D.

Every region seems to have its own nightmarish perennial weeds that defy all reasonable control efforts. In the southern coastal plain, it is common Bermuda grass. In the Mississippi River Delta and Piedmont, it is Johnson grass. Elsewhere, tall fescue carries that dubious honor. In each case, these perennial grasses were/are forages for grazing or hay.
The resiliency that makes them ideal forages makes them tenacious weeds. Fescue is not an exception to this pattern. Fescue is an introduced cool-season perennial grass that is commonly planted for livestock forage and as a cover crop for CRP and strip-mine reclamation sites. Individual fescue plants tend to grow in clumps, with established plantings forming a seemingly impenetrable mat of fescue. In addition to the robust competiveness of established fescue stands, the species produces compounds that inhibit growth of other plants (allelopathy). The importance of fescue as a crop is shown by an estimated 32 million acres planted in the United States. These diverse uses, particularly those as a cover crop at locations that have poor soils, are testimony to the adaptability of fescue to a broad array of soil and environmental conditions. The importance and value of fescue as a crop cannot be overstated. Despite the value of fescue as a forage and cover crop, in some settings the species can be a serious weed that necessitates control. Fescue has a symbiotic relationship with a fungus (called an endophyte) that lives in the intracellular spaces of fescue leaf sheaths and seed. The endophyte produces an alkaloid that sickens livestock and possibly wildlife. Cattlemen invest considerable resources to kill endophyte-infected fescue and convert the sites to endophyte- free fescue. Further, fescue is not a desirable food source for wildlife and produces a poor habitat. This became particularly evident when fescue was planted large-scale on CRP land. Now, there is interest in converting fescueplanted CRP land to native grass species that are more conducive for wildlife, particularly ground-nesting birds. There has been considerable research effort to develop systems of fescue control for these two distinct situations. Embedded in those research results are clues for effective fescue control in food plots for whitetail deer.


 Fescue will not be easy to control and will require a multi-year effort. A critical component in a long-term fescue control program involves treating fescue stands with glyphosate during fallow periods before food plot establishment, with two applications needed for adequate performance. Dense fescue stands tend to have copious amounts of dried fodder that impedes herbicide spray from contacting new growth. Therefore, it is often necessary to closely mow or burn established fescue sites before applying glyphosate. This stimulates fescue re-growth, which will readily absorb glyphosate. This initial treatment is typically in late-summer to early-autumn, when fescue growth is resuming after summer dormancy. A sequential glyphosate application is required the following spring to control fescue originating from seed and re-growth of plants that survived the initial treatment. The second application should be made once fescue growth resumes after snow melt and when frost/freezing temperatures are not expected. It pays to not be chintzy when using glyphosate for fescue control. Remember, fescue is a tenacious perennial grass and glyphosate rates need to be within the recommended rate range of 0.7 to 2.0 qts./A, based on the stage of fescue growth. Although glyphosate often does not need additional adjuvants, fescue control is an example where additional surfactants and ammonium sulfate might be needed to ensure maximum efficacy. Refer to the glyphosate label for detailed information on rates and adjuvants, which vary among the many glyphosate products. A discussion on herbicide options to control fescue would be incomplete if I did not discuss the role of selective post-emergence grass herbicides like Arrest and other herbicides in the same chemical family. The post-emergence grass herbicides as a group are not overly effective in controlling established fescue. Higher rates and multiple applications help control fescue emerging from seed. However, established fescue is very difficult to control outright with any of the post-emergence grass herbicides. Fallow applications of glyphosate are much more effective. Some readers may have determined through their own literature searches that the residual herbicide imazapic (Cadre, Plateau) is often combined with glyphosate to control fescue in transition to plantings of native grasses in CRP plantings. This is not an option for fescue control in food plots. Imazapic has significant soil residual properties, and carryover from applications to control fescue will stunt or kill most forage species planted in food plots.


In regions with extreme winter temperatures, fallow tillage with a heavy disk in the autumn will fragment dense fescue mats and predispose fescue to winter kill. However, autumn tillage alone is marginally effective since seedling emergence from the seedbank and surviving plants may regenerate the fescue stand. Follow-up spring tillage once the soil has thawed will improve overall fescue control. Fallow tillage to control fescue may not be advisable at all locations due to potential for significant soil erosion. If sites are erodible, consider leaving non-tilled swaths along the contour to slow lateral water flow. These non-tilled strips can be tilled later once the initially tilled areas are planted to another species. Of course, glyphosate is an option in erodible areas.


Cover crops serve two roles in the management of fescue when used in conjunction with glyphosate and tillage. First, warm-season cover crops planted after the spring treatments will further suppress any remaining fescue survivors and emerging seedlings. Ideal cover crops are those that are quickly established and produce dense growth that shades the soil surface. Second, the warm-season cover crop can easily be a forage tailored to attract and nourish whitetail deer. Whitetail Institute’s Power Plant, an annual warm-season forage blend, is an ideal choice for this use. Previous articles stressed the importance of a balanced system of weed management for food plots. Fescue is a good example of a weed that needs a balanced, integrated strategy for long-term control starting in fallow periods. Trying to control fescue once the permanent food plot is established is usually futile. Each food plot system is unique and a “one size fits all” recipe for fescue control is not possible. Consider your food plot location, logistics, forage crop rotation sequence, and availability of equipment to create your own plan to control fescue that uses multiple applications of glyphosate, fallow tillage, and strategic plantings of weed-suppressing cover crops. This may take at least 18 months to implement, but it is necessary to effectively manage this troublesome perennial grass.