University of Illinois Extension
Bruce Spangeberg

These articles are written to apply to the northeastern corner of Illinois. Problems and timing may not apply outside of this area.

Stateline Yard & Garden

Warm-Season Grasses Turn Brown Early

September 27, 2001

As we advance into fall, brown or straw-colored patches of grass often appear in lawns. In some cases, the entire lawn turns a straw color. One of the more common reasons for this is these are warm-season grasses.

Most grasses in northern Illinois lawns are cool-season species, which stay green for much of fall because they thrive in cool weather. Warm-season grasses turn brown with cooler weather in fall. Perennial species will go dormant and return to green very late next spring or early summer. Warm-season annuals die and must regrow from seed to appear next season.

Crabgrass, a warm-season annual, was common in lawns this year. As crabgrass turns brown in fall, it is dead, and the same plant will not return next season. Seeds on the soil surface must germinate next year for the problem to occur again. Preemergence herbicides (crabgrass preventers) can be used next season to help prevent the return of crabgrass in the lawn.

Zoysiagrass is a most common perennial warm-season grass in our area. During a hot summer zoysiagrass lawns are most likely the greenest on the block. Then with the return of cool weather in September, zoysiagrass starts turning yellow, then a straw color. Zoysiagrass is not dead, but it will not green up until significant warmth returns sometime next year.

An additional warm season grass that appears as straw-like patches in fall is nimblewill. Nimblewill will appear as patches of fine grass, usually in shade locations. These patches become very conspicuous in fall and next spring.

One control option for zoysiagrass or nimblewill is to dig it out, making sure to get all the creeping stems and roots. Another option is to apply the herbicide glyphosate (Roundup, Kleeraway), but the grass needs to be green and growing to be killed. Probably the best time to do this would be next August, so the area can be reseeded afterwards.


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