A dense, vigorous stand permits little light to reach below the canopy, preventing summer annual weeds from becoming established. Proper fertilization, irrigation, and production practices usually make an herbicide application unnecessary. Residual activity of winter herbicides in soil also helps lessen, but does not always eliminate, summer annual weed problems. Occasionally, pigweed, lambsquarters, green foxtail, Russian thistle, and other weeds infest second and third cutting. These weeds, with the possible exception of green foxtail, are usually a problem only in older, depleted stands.
Green foxtail is an aggressive summer annual grass.
It has been a major problem in some areas for many years and is an increasing problem in other areas. Trifluralin is very effective against green foxtail, barnyardgrass, and most common summer annual broadleaf weeds. Apply Treflan in March to early May, before summer annual weed emergence. Rainfall or overhead irrigation must follow within 3 days, or else reduced weed control may result. Because of the short growing season and small number of cuttings in some areas, reducing the rates of using Treflan every other year is usually sufficient for excellent summer annual weed control.