Organic mulches, such as shredded cypress and pine bark, are commonly used in commercial and home landscapes. While providing numerous benefits (soil moisture conservation, weed suppression, aesthetics), mulches also provide a substrate for a diverse group of saprophytic organisms (saprobes), such as mushrooms and slime molds. While often causing alarm to gardeners unfamiliar with them, saprobes do not infect plants or cause plant diseases.

Saprobes are microorganisms, like fungi and slime molds, which decompose plant materials (including wood mulch and leaves). These scavengers get their nutrients from non-living, organic materials.

These DO NOT cause plant disease. Saprobes are essential parts of the garden since they help to completely recycle nutrients.


Slime molds are single-celled, amoeba-like organisms that become visible as aboveground colonies. With extended rainfall events, they grow out of the soil and creep onto mulch and other surfaces.

After a brief, slimy stage, they become dry with masses of dark, powdery spores (reproductive stage). A very commonly seen slime mold is the dog vomit fungus (see photo).


Mushrooms are the fruiting structures of certain types of fungi, most of which are beneficial. The bulk of the fungus lives within mulch or soil unnoticed for the most part. With rainfall events, the fruiting body, the mushroom, comes up and is visible to us.

Many mulch fungi have non-typical aboveground reproductive structures that emerge after rainy weather. Some of these include stink horns, puff balls, birds nest fungi, and artillery fungi (see photo).


In general, fungi fruiting structures are only an aesthetic problem. They can be left alone – they will dry up and disappear. Underground structures will remain so under wet conditions, mushrooms will probably appear again.

Sometimes it’s necessary to remove poisonous species to prevent kids or pets from eating them. Identification is the tricky part and may be difficult. Wear gloves when removing mushrooms, just in case.

Slime molds are harmless and only emerge for a short time under wet conditions. They will dry up and the dried masses can be raked or swept off. However, slime molds will reappear.

For more information, contact the Pulaski County Extension Service at 606-679-6361 and request the brand new publication Mulch, Mushrooms, Slime Molds, and Other Saprophytes (PPFS-GEN-06). Learn about timely events or things to do in your home gardens by becoming a fan of Pulaski County Horticulture on Facebook, or following @hortagentbeth on Twitter, kyplants on Instagram, and Pulaski County Horticulture YouTube channel.

The Pulaski Co Extension office is open to the public by appointment only through the month of July. Extension employees are still on the job and can be reached via office phone. Read the entire directive on the Pulaski County Cooperative Extension website at

The Lake Cumberland Master Gardeners are temporarily out of pine straw. Another load will be coming soon.

Educational programs of Kentucky Cooperative Extension serve all people regardless of economic or social status and will not discriminate on the basis of race, color, ethnic origin, national origin, creed, religion, political belief, sex, sexual orientation, gender identity, gender expression, pregnancy, marital status, genetic information, age, veteran status, or physical or mental disability.

Recommended for you