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Problem: Slime Mold - Physarum cinereum; Mucilago spongiosa

Slime mold on turf

Hosts: All turfgrasses

Description: Slime molds are commonly found in turf, ornamental, and garden plantings in the home landscape. Slime molds are primitive organisms that feed on bacteria, other fungi and dead organic matter. Slime molds often cause concern to homeowners because their reproductive phase is colorful and quite noticeable on plant parts. 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. Generally, these fruiting structures, ranging in size from small pinhead-size flecks to lumps several inches in diameter, form in small patches (less than one foot diameter) in the lawn. In these small patches, turfgrass foliage may be dotted with the fine specks of the slime mold, or in some cases completely covered by the fungal mass. During wet weather, the fruiting structures may appear slimy. As the structures dry out in hot weather, they become powdery, and break up easily upon touching. Although unsightly, the slime molds do not parasitize living plants. Plant structures, such as leaves and stems, serve only as a means of support for the development of the slime mold fruiting structures. Heavy infestations of slime mold may cause a slight leaf yellowing resulting from partial shading of the photosynthetic area. Nevertheless, slime molds rarely, if ever, cause permanent damage to plants.

Recommendations: Chemical control of slime mold is not necessary. Frequent mowing and removal of the fruiting structures from plant parts by raking or watering is generally sufficient to improve the appearance of the plant. Excessive thatch or accumulation of organic matter may increase the incidence of slime mold. Therefore, thatch control may help alleviate this problem.

References:

1. Slime Mold, K-State Research and Extension Plant Pathology Fact Sheet.

 

Last Update: 01/23/2004


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