Good Morning, 

Thank you for contacting the U of M Extension Service. 

From viewing your photos, I believe the substance is slime mold. Please click on the following link from the U of M Extension Yard and Garden website: https://extension.umn.edu/lawn-care/common-fungi

This information states: 

Slime molds are not parasitic, so they do not cause plant disease. But heavy coverage on grass or plant leaves may cause yellowing.

• Control is not usually necessary and slime molds will disappear during hot, dry weather.
• Slime molds may be washed, brushed or raked from affected areas.
• Frequent mowing will quickly remove these fungi on rapidly growing grass.

Good Luck!



You are welcome!