Nostoc: A slimy-green substance in your lawn

Source: Sharon Flynt, UK extension horticulture agent

With a wetter-than-normal fall in Kentucky this year, you may have noticed a slimy-green substance has appeared in spots in your lawn overnight. Don’t panic; it is not an extraterrestrial that will kill your lawn or pets.  It is actually nostoc, a cyanobacterium and a hardy survivor that has been around for approximately 3 billion years. In its dormancy stage, nostoc will appear black and crusty, and when wet, it resurrects itself into a green moist mass. It can grow anywhere, from rocks to pavement, making surfaces very slippery. It is very hard to kill. The good news about nostoc, however, is that it is basically harmless, even if it is gross-looking. Nostoc can be a safety hazard when it is in the slimy-green stage as it can cause you to fall.

Nostoc in your lawn can indicate a drainage problem. You may need to improve the drainage in that area.  Also, do not overwater the area and check its soil fertility. Too much phosphorus in the soil can spur its growth, so get a soil test from the Cooperative Extension Service office in your county and follow the fertilizer recommendations. It can help improve the situation. 

Contact (YOUR COUNTY) office of the University of Kentucky Cooperative Extension Service for information on nostoc.   

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