Slime Mold

The following question was sent to the P&PDL diagnosticians here at Purdue University:

Question: We have a creamy yellow (creamy tan?) substance on the mulch and some plants in the mulch. It seems to appear after the lawn is watered. At first, we mistook it for animal excrement. When it gets wet, it make a brown powdery dust. What is is??? How can we get rid of it???

Question: Help! What is this yellow goopy, fast growing mold like stuff growing around my home and on the mulch in my garden? My neighbor has it too. We have even found it in the soil next to the foundation. Do I need to be concerned? How do I get rid of it? Could it be contributing to my recent development of allergies? Hope you can help! Thanks so much.

Question: On the north side of my garden there is a small area which hasn't been cultivated. Have noticed recently some sort of mold/fungi: The description is as close as I can get: White, blobby, sticky with a tendency to spread out tentacle-like. Looks like "baby throw-up", but white. It seems to be spreading at an alarming rate. Can you help me?

slime moldAnswer: What you are likely observing is a type of fungus, called a slime mold. These fungi live on dead organic matter, such as wood mulch. The slime mold is yellow-tan in color and has no definite shape. Although slime molds may grow on plants, they do not harm plants. They thrive in moist conditions, therefore, they may be appearing now as a result of recent watering. Slime molds will eventually disappear on their own. If you want to speed this process, rake the mulch to promote air drying.

As to your allergies, I do not know whether the slime molds are causing your problem. There are a number of plants that are pollinating now that could be causing your allergies; however, you could also be allergic to something in your home. It is best to consult with a physician concerning your allergies. You might want to consider having someone else rake your mulch.

(Photo of slime mold courtesy of George Knaphus at Iowa State University.)

- Peggy Sellers, Director of the Plant and Pest Diagnostic Laboratory