Turf - Brown Turf Areas in Spring

You may still be seeing brown areas in lawns that have greened up this spring. These are places where warm season grasses were dominant last year. The following is an article on the subject.

Cool season turfgrasses have greened up across the state. However, there will often be distinct areas of turf that remain brown or straw colored. These are areas where warm season weeds died out or went dormant last fall. It is important to take note of these areas and determine what control measures will be necessary this season. Crabgrass is the most common weed that winter kills leaving large browned out areas. Goosegrass could also be the culprit, especially in compact areas. Crabgrass and goosegrass are annual species that will come back from seed. Crabgrass is germinating in turf now, goosegrass will be germinating as we go into May. If you have missed the timing for crabgrass preemergence applications, dithiopyr (Dimension) is an option now as it has both preemergence and early postemergence activity on crabgrass. However, it is not safe for areas that have been or will be seeded this spring. For new seedings, quinclorac (Drive) would be the best option as a postemergence herbicide once all the crabgrass has germinated (May). Quinclorac will not control goosegrass.

Brown areas may be patches where perennial warm season grasses grew last year. These grasses will begin to regrow again in May. Bermudagrass (or wiregrass) is the most common warm season perennial grass weed that appears brown in dormancy throughout the state. Zoysiagrass is possible but usually restricted to areas near to where it was planted. Another possibility commonly found in Delaware is nimblewill which will appear as fuzzy looking patches. Both Bermudagrass and zoysiagrass spread by underground rhizomes whereas nimblewill does not. Control of these three perennial warm season grasses is difficult. Total renovation with several applications of glyphosate herbicide is often needed. Post emergence suppression of Bermudagrass can be accomplished with multiple applications of fenoxaprop (Acclaim Extra) in tall fescue turf.

Gordon Johnson, Extension Horticulture Agent, UD, Kent County