Preemergence Herbicides for the Control of Annual Foxtails in Established Grass Pastures and Hayfields – Timing is everything.
Bob Stougaard, Professor and Extension Weed Specialist, UGA – Athens and
Nicholas T. Basinger, Associate Professor of Weed Science, UGA – Athens
Preemergence herbicides labeled for use in established pastures and hayfields include Prowl H2O (pendimethalin) and Rezilon (Indaziflam).
Growers may apply Prowl H2O for preemergence control of annual foxtails in Bahiagrass, bermudagrass, and tall fescue. For tall fescue, uniformly apply at a broadcast rate of 1.1 to 4.2 quarts of Prowl H2O per acre in a single application or sequential applications made 30 or more days apart. Do not apply more than a maximum cumulative total of 4.2 quarts of Prowl H2O per acre per year. Note that Prowl H2O also controls Italian ryegrass when rates exceed 4 pts/A.
For bahiagrass and bermudagrass, apply Prowl H2O preemergence early in the spring before green-up at a broadcast rate of 1.1 to 4.2 qts/A. Do not apply to Bahiagrass and bermudagrass after green-up in spring before first cutting. Prowl H2O may also be applied sequentially when the initial application is made in the dormant season and the subsequent application is made in-season between cuttings. Do not apply more than a maximum cumulative total of 4.2 qt/A per year.
Rezilon (Indaziflam) can be used for preemergence control of annual foxtails in established bermudagrass and bahiagrass. Rezilon can be applied at 3-5 fl oz per acre in a single preemergence application. Rezilon can also be applied preemergence early in the season at 3 fl oz/A followed by 3 floz/A mid- to late-season. Do not exceed 6 fl oz/A of Rezilon in a 12-month period with sequential applications.
Do not overseed cool season grasses (e.g. Italian ryegrass, wheat, etc.) for winter grazing for a period of at least 18 months after the last application of Rezilon. Similarly, do not rotate to other crops for a period of 22 months after the last application of Rezilon. When Rezilon is applied at a rate greater than 3 fl oz/A, hay may not be harvested until 40 days after application. There are no grazing restrictions following the application of Rezilon.