Introduction
Pasture establishment is an expensive venture, and it is important to get the forage growing as quickly and vigorously as possible. In addition to good soil conditions, weed management is necessary to encourage rapid forage growth. This publication details techniques for chemical weed control prior to and during pasture establishment and is intended for county Extension faculty as well as owners and managers of grazing lands.
The soil is full of weed seeds, commonly referred to as a soil seed bank. In pastures that need renovation, weed control during and after pasture establishment will likely be necessary. This is true even for pastures that were relatively weed-free prior to renovation.
The first step in pasture renovation includes removing the existing vegetation. In most cases, 3–4 qt/acre of glyphosate will kill all living plant material, except for woody species. For some species, such as palmetto, more drastic measures are necessary. Once the plant material is dead, it will be necessary to till the pasture repeatedly by disking and/or rotovating. Repeated tillage is necessary to prepare a clean, weed-free seed bed prior to planting. If tillage applications are spaced 2–3 weeks apart, many weed seeds will germinate and be destroyed by subsequent tillage operations. This repeated tillage will help to deplete the soil seed bank.
The next step entails planting the desired forage. UF/IFAS has detailed instructions for establishing forage grasses. See EDIS publication SS-AGR-161, Forage Planting and Establishment Methods on Prepared Seedbed (https://edis.ifas.ufl.edu/ag107) or consult your local UF/IFAS Extension agent for recommendations.
Most weeds will emerge shortly after the grass has been planted. Therefore, time is of the essence for weed control operations. In most cases, sedge (Cyperus spp.) species tend to be the most problematic, but broadleaf weeds can quickly become established as well.
The best weed control strategies for each pasture grass during establishment are outlined below.
Bahiagrass (Argentine, Pensacola, Tifton-9, etc.)
Herbicides should not be applied to young bahiagrass seedlings. Apply herbicides only after bahiagrass has at least 6 inches of growth. Repeated mowing is the only option for suppressing weeds during bahiagrass establishment.
Bermudagrass (Florakirk, Jiggs, Tifton-85)
Apply 2 pt/acre of WeedMaster (2,4-D + dicamba) 7–10 days after planting. Outrider (sulfosulfuron) herbicide may be applied at 1.0–1.33 oz/acre no earlier than 2 weeks after planting.
Stargrass (Florico, Florona, Okeechobee, Ona)
Apply 2 pt/acre of WeedMaster 2,4-D + dicamba 7–10 days after planting. Alternatively, apply 0.78 lb 2,4-D with 0.22 lb of dicamba. Outrider herbicide may be applied at 1.0–1.33 oz/acre no earlier than 2 weeks after planting.
Limpograss (Floralta, Gibtuck, Kenhy)
Apply 0.75 lb/acre of dicamba 7–10 days after planting. There are several dicamba-containing products. Outrider (sulfosulfuron) herbicide may be applied at 1.0–1.33 oz/acre no earlier than 2 weeks after planting. Limpograss is sensitive to 2,4-D applications; this herbicide has been shown to kill limpograss when applied soon after planting.
Conclusion
Applying herbicides 7-10 days after planting bermudagrass, stargrass, or limpograsswill results in quicker pasture establishment than without herbicide application. If this window of opportunity is missed, Outrider at 1.0–1.33 oz/acre, plus 2,4-D + dicamba (or dicamba for limpograss) at the above rates should provide excellent weed control. No herbicides should be applied to bahiagrass or seeded varieties of bermudagrass until plants are at least 6 inches tall. Do not use Outrider on seedling bahiagrass or bermudagrass, or complete kill will occur; however, it is safe once established (~ 1 year after planting).