Archive for Sunday, June 23, 2002

Slime mold looks worse than it is

June 23, 2002


Now that the lawns have enjoyed a wonderfully cool moist spring, it is time to look ahead toward summer.

The warmer, drier conditions mean less mowing and more time for other activities. However, several people are concerned about sooty-gray patches popping up in the middle of the turf.

With so many things that can go wrong in an established lawn this time of year, these patches of slime mold are no cause for alarm.

Slime mold is a primitive organism that is commonly seen on turf. Large numbers of small gray, white or purple fruiting structures, called sporangia, form on the leaf blades during cool, humid weather throughout spring, summer and fall.

Affected areas are often from several inches to about 1 foot in diameter. During wet weather, the fruiting structures may appear slimy. As the structures dry out in hot weather, they become ash-gray and break up easily when touched.

Homeowners often are concerned that this is a disease organism that will kill the grass. Actually, slime mold feeds on bacteria, other fungi and dead organic matter. It simply uses the turf as a structure on which to grow.

The only way slime mold can damage turf is by completely covering individual leaf blades and interfering with photosynthesis. The physical shading of the blades may cause the patches to turn yellow for a short period of time. However, when the dried mold is washed off with water or blown away by wind, normal growth of the plant will resume.

Because slime molds are harmless, no chemical control is necessary. Use of a broom or a heavy spray of water often is sufficient to remove the mold to reveal the healthy turf underneath.

Bruce Chladny is horticulture agent at K-State Research and Extension-Douglas County. For more information, call him at 843-7058 from 8 a.m. to 5 p.m. weekdays.

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