Applying Herbicides

Without disturbance, both warm-season and cool-season grassland fields often become dominated by dense sod or a single species of grass (monotype). This reduces habitat quality for a number of wildlife species. Herbicides can improve plant diversity by reducing the vigor and abundance of dominant plants that crowd out other desirable plants. Sprayed areas will soon produce a wide array of plants, providing a greater abundance and diversity of grasses, forbs, legumes, seeds, and insects. Used properly, chemical suppression is an excellent way to enhance grassland habitat for bobwhite quail and other wildlife. Use this practice to set back grasses and improve habitat quality on fields dominated by perennial forbs or broad-leaved plants.

Remember, for habitat-management purposes, spraying is not meant to completely eradicate vegetation but to reduce its vigor and abundance. Use herbicides at label rates to set back, or suppress, but not eliminate vegetation. To be effective, herbicides must be applied when dominant vegetation is actively growing. Weather conditions, which will influence vegetation growth, may result in narrowing these dates. Use grass-specific herbicides on fields rich with native wildflowers.

Spray Dates for Different Plant Types

Recommended Spray Dates (Conservation Reserve Program spraying dates may differ)

Cool-season grasses (fescue, brome, orchard grass, etc.) March 15 to May 15 or October 1 to December 1

Warm-season grasses (Indian grass, big bluestem, etc.) May 1 to September 1

Apply spray in blocks or strips on one-third (preferred) to one-half of the field each year. Best results occur when different areas in the field are sprayed different years. If strip spraying, strips should be 25–75 feet wide.

Separate strips from each other with an area of undisturbed vegetation twice as wide as the sprayed strip. Ideally, sprayed strips should be as long as possible and should follow the contour of the field to prevent erosion. One year later, spray a new block or strip of similar size next to the unsprayed area. Spray the final undisturbed block or strip the third year. This develops adjoining strips of vegetation of three different ages, providing three different stages of plant succession. Re-treat sprayed areas as needed to maintain desired plant diversity.

In areas of heavy growth, you may need to conduct a prescribed burn or mow to remove dead or tall, thick vegetation before spraying. Allow the burned or mowed vegetation to grow 6–8 inches before spraying. You can also disk or burn after the herbicide application to further enhance habitat conditions. Note: Always read and follow all herbicide labels.

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