Dealing with Grass and Weed Problems

By Jon Cooner

 If you’ve ever planted anything, you’ve undoubtedly had unwanted grasses and weeds show up at some point. The same is true of Whitetail Institute perennial plots. Even if you planted the plot according to Whitetail Institute guidelines, you can bet that grass and/or weeds will probably appear sometime during the life of the plot. There are a couple ways to control grass and weeds that show up in perennial plots after planting — mowing and, if appropriate, applying selective herbicides such as the Whitetail Institute’s Arrest grass herbicide and Slay weed herbicide.
Mowing is a recommended step in maintaining Whitetail Institute perennial plots during the spring and summer, and for a number of reasons, including weed control. Keeping weeds mowed so that they never have a chance to flower (produce seed heads) can break the reseeding cycle of annual weeds. The key is to mow weeds soon after they appear and, if necessary, keep mowing them periodically throughout the spring and summer to prevent them from flowering. Just don’t mow if it’s hot and dry.

Mowing during the spring and summer also helps keep perennials highly attractive by stimulating them to produce lush, new growth. Because Whitetail Institute perennials grow from the root system and can live for years without relying on flowering to reseed themselves — a process that robs plants of huge amounts of nutrients and energy— mowing them helps keep nutrients and energy in the foliage where they are available to deer. Selective herbicides such as Arrest and/or Slay may also be appropriate for use in grass and weed control, depending on a number of factors, such as forage blend and types of vegetation infesting the plot. Arrest is labeled as appropriate for controlling most kinds of grass in any Whitetail Institute perennial plot and in other varieties of clover and alfalfa. Slay is labeled as appropriate for controlling many kinds of broadleaf weeds in Imperial Whitetail Clover, Alfa-Rack and other varieties of clover and alfalfa. Be sure to check Arrest and Slay labels for additional information on the proper use. The labels are also available online at For optimum results, grass- and weed-control efforts should be started early.

The Whitetail Institute recommends that its perennials be mowed starting shortly after green-up each spring. Also, if grass or weeds are to be controlled with Arrest or Slay, the best time to spray them is shortly after the grass or weeds emerge and before they grow to a height of six inches. But what if you didn’t control your grass and weeds early and now your plot is infested with mature grass or weeds? Is all lost? Not necessarily. It will be much harder to control grass and weeds once they mature, but it may not be impossible. Only you can decide whether to try to eliminate the infested plants or start over with a new planting. The following tips may help you make an informed decision and, if you decide to try to control mature grass and weeds, maximize the results of your efforts. There are a few things you should consider when deciding whether to embark on a catch-up project to try to control mature grass or weeds in an existing Whitetail Institute perennial plot. First, it makes sense to do a cost/benefit analysis to see whether you will come out better financially by throwing in the towel and starting over with a brand new planting. In the long run, replanting may be the better option if your plot is heavily infested and/or several years old and near the end of its intended lifespan. Also keep in mind that, while mowing mature grass and weeds may make them more susceptible to the effects of Arrest or Slay, the plants will still be mature and, therefore, harder to control than seedlings. Weather should also be considered since you should not mow or use Arrest or Slay when it is excessively hot, dry or droughty. If you decide to try to control mature grass and weeds rather than starting over with a new planting, be sure that you get started a month or more before grass and weeds in your area will begin to go dormant in the fall. This is necessary because grass and weeds must be controlled when they are actively growing. Start by mowing your plot to a height of six inches, and then wait until grass and weeds show signs of new growth (usually a week or two). Once new growth is apparent, spray the entire plot with Arrest and/or Slay if appropriate, and use the maximum concentration for the herbicide as listed on its label. The addition of an adjuvant, such as a surfactant or crop oil concentrate, to the Arrest spray mixture is not required for Arrest to control seedling grasses. However, adding an adjuvant to the Arrest spray mixture according to label instructions may increase its effect on mature grasses.

If you are trying to control both grass and weeds in clover or alfalfa, spray Arrest first, and then spray Slay a minimum of three days later. Arrest and Slay begin to work almost immediately, but be patient. You should start to see grass and weeds starting to yellow within two to three weeks. Then, be sure to resume your grass and weed control efforts, including periodic mowing. Again, remember that spraying mature grass and weeds may not be as effective as compared to spraying seedlings. These tips should help you make an informed decision on whether to spray a plot infested with mature grass and weeds and how to spray it, or simply replant. Maintenance recommendations for Whitetail Institute perennials are provided on the back of each product bag and are available on-line at The Whitetail Institute’s in-house consultants are also standing by to answer your questions about food-plot maintenance at our toll-free number, (800) 688-3030, ext. 2, between the hours of 8 a.m. and 5 p.m. Central time, Monday through Friday.

Other Important Information Concerning Grass and Weed Control

Arrest can be used on all Whitetail Institute forage blends, and Slay is labeled as appropriate for use on some Whitetail Institute forage blends but not on others. Slay contains a pre-emergent that is residual. Timing of herbicide applications may be affected by many factors, including the time since the last mowing, weather conditions, age of the food plot and other factors. Be patient, because although Arrest and Slay begin to work almost immediately, it can take a few weeks for the weeds or grass to begin to yellow. Arrest and Slay produce best results on seedling weeds and new growth, but recently planted plots may not be appropriate for herbicide application. Always read and follow the label instructions when using these, or any other, herbicides and adjuvants (crop oil, surfactant or sticking agent). If you have any questions, call our in-house consultants at 800- 688-3030, ext. 2.