We now have more flexibility with Prowl H2O, an herbicide previously approved only for dormant bermudagrass. It is now labeled for use on cool-season forage grasses, with or without alfalfa (but not clovers), and on warm-season grasses. However, grasses must be well-established with at least six tillers before application.
Prowl H2O can be used for forage production, including hay, silage, and green chop, and in pastures for livestock grazing. It can be applied by ground, air, chemigation, or mixed with dry fertilizer. The application rate ranges from 1.1 to 4.2 quarts per acre, with research showing that a split application of 2.1 quarts followed by another 2.1 quarts provides the most effective season-long weed control.
This herbicide controls a variety of weeds. At rates below four pints per acre, it targets crabgrass, foxtail, pigweed, henbit, and others. At four pints or more per acre, it is effective against annual bluegrass, ryegrass, chickweed, mustards, and other species. However, Prowl H2O does not control emerged weeds. For best results, it must be incorporated into the soil by at least 0.25 inches of rain within seven days of application.
There are no grazing restrictions, meaning livestock can graze immediately after application. However, grasses cannot be overseeded for 10 months after use. Prowl H2O can be applied in the fall, spring, or in-season between cuttings, with a minimum of 30 days between applications. The largest total allowed per year is 4.2 quarts per acre.
Research from Penn State, the University of Delaware, and Virginia Tech confirms that a split application provides the best season-long control of crabgrass. A single application of 4.2 quarts per acre lasted about 12 weeks but did not offer full-season control. Additionally, studies found that a 2.1-quart application effectively controlled giant foxtail.
By following these guidelines, you can effectively manage weeds and maintain productive pastures and forage crops. Always refer to the product label for specific application instructions and tank-mix compatibility. You can contact your County Agent for more information.
