Slime Mold Is Causing Concern

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Have patches of black suddenly appeared on your turf? They are probably slime molds that can be unsightly but are not considered harmful. In fact, they are actually thought of as being beneficial.

The slime mold spores that live in the soil and thatch are primitive organisms with an identity crisis. They resemble fungi and some scientists consider them to be part of that kingdom but others now place them in the Kingdom Protista.

Slime mold creeps along leaf blades gaining nutrients from bacteria, fungi, other molds and decaying organic matter. They do not damage the turf. Slime molds often disappear after 2 or 3 days. They may cause limited yellowing of the blades of grass due to the shading.

Slime molds may be found on all cultivated and weedy grasses. They frequently follow a period of dryness followed by prolonged periods of leaf wetness. The spores germinate and develop into a slimy mass after heavy rain. They are found from late spring to late fall. Slime molds may reoccur in the same location each year when conditions are favorable. Poor drainage and heavy thatch enhance the likelihood of their development.

There are various species of slime molds, each resulting in discolored, irregular patches from a few inches to several feet in diameter. The spore masses are only about the size of a pinhead and are typically grayish-white, blue-gray or ash colored with purple spores.

You can just let nature take its course and they will disappear. If rapid removal is desirable, use the forceful spray of a water from a garden hose to wash them away. Remember that moisture does further the development or spread of the fungus. The pustules may also be removed by brushing or mowing the turf.