Cool-season weeds become a major problem on most bermuda sport fields. Although bermuda is very competitive against weeds during the summer, it allows many weeds to infest during its dormancy/no-growth period of late winter and early spring. A few weeds (maybe a 5-10% ground cover) are not a serious problem, although they do aesthetically detract from an otherwise uniform brown surface. On the other hand, a weed population of 25% or more is a serious problem since the weeds compete with the bermuda as it begins to green-up in April. Weed-covered bermuda may not actually green-up until early June or July. This late green-up makes it difficult to evaluate previous winter damage and it shortens the period for the bermuda to develop a dense, resilient turf. Sometimes perennial grasses such as tall fescue, Kentucky bluegrass and perennial ryegrass become established throughout a field and they can become the dominant grass. These cool-season perennial grasses must be controlled in order to develop a high quality, dense, resilient and aesthetic bermuda field. 

METHODS OF CONTROL 

WINTER COVER 

If a field is covered with four to six inches of straw or a dark-colored synthetic fabric to protect bermuda from winter-kill, winter weeds do not usually cause a problem. A synthetic cover that allows light to penetrate will greatly increase winter weed growth and cover. Of course, if the straw blows off in some areas of the field , weeds will appear. If the straw also contains wheat or barley seed these annual, coarse-bladed grasses will become very competitive. If this does happen, as soon as the straw is removed from the field, mow the small grain as short as possible with a rotary mower and continue mowing at a height of about one inch. This weakens the small grain and causes it to die much quicker when hot weather arrives. 

BURNING 

Controlled burning of a field is an excellent method of getting the dead bermuda foliage off the surface, encouraging earlier green-up, getting rid of the straw cover used for winter-kill protection, and killing many of the actively growing weeds. Burning will not hurt the bermuda and, unfortunately, it won’t kill all of the perennial weed grasses such as ryegrass and bluegrass. To burn effectively, the field must be very dry. Wind should be at a minimum in order to control the burn rate and to keep the fire from sweeping over the bermuda, without effective burn. Burning is illegal in most cities unless you first get permission from the local fire department. 

HERBICIDES 

Round-Up (glyphosate) applied on late February or a very early March is one of the best ways to control winter annuals such as Poa annua (annual bluegrass), chickweed and henbit. It also will control perennial grasses such as tall fescue, Kentucky bluegrass and perennial ryegrass. Round-Up should be applied at one to two quarts per acre. If the weather is very cold and/or the weeds have grown very little, you will not likely get 100% control. Repeating the application the following year should get rid of the remaining perennial grasses. Since there is usually an ample supply of annual bluegrass, chickweed and henbit seed in the soil, applications of Round-Up are usually needed every one to three years. 

Precautions when using Round-Up: 

1. FOLLOW THE LABEL - it’s the law. 
2. DO NOT apply Round-Up to bermuda turf that is not dormant (brown). We occasionally have a very mild winter in which bermuda will not go 100% dormant. If you can see a few green leaves located deep in the canopy, even in February or early March, you should not spray. Revolver and Monument are relatively new herbicides that can be applied at very low rates. These will kill Poa annua, overseeded perennial ryegrass and some broadleaf weeds if applied when weather is not cold and when the weeds are growing rapidly. Manor is similar to Revolver and Monument but has little activity on Poa annua. However, Manor is much superior to Revolver and Monument if broadleaf weeds are the main problems. These herbicides can usually be effective applied anytime after May 1. They are very safe on bermuda.