What is this repulsive yellow blob appearing on my mulch?

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Question What is this repulsive yellow blob appearing on my mulch?

Answer The blob is probably a slime mold. It is neither plant nor animal. Slime molds may be slimy, but they are not molds either. True molds are fungi. The ingestion of food is one reason slime molds are not considered to be fungi. Fungi produce enzymes that break down organic matter into chemicals that are absorbed through their cell walls, not ingested.

Slime molds exist in nature as a plasmodium, a blob of protoplasm without cell walls and only a cell membrane to keep everything in. It is really nothing but a large amoeba.

They may be white, yellow, orange, or red. The color of a particular species can vary slightly with temperature, pH, and the substances the plasmodium eats. One very common slime mold, Fuligo septica, looks like scrambled eggs. Fuligo septica has many common names, including Dog Vomit Slime, Troll Butter, Flowers of Tan, and Flowers of Sulphur.

This yellow blob is actually a huge single cell. Unlike most cells, which have only one nucleus, this cell contains millions of nuclei. One fascinating thing about plasmodial slime molds is that the millions of nuclei in a single plasmodium all divide at the same time. This makes slime molds ideal tools for scientists studying mitosis, the process of nuclear division.

Slime molds have become popular lab subjects. Scientists and mathematicians use them to study an astonishing array of areas in medicine, developmental biology, computer modeling, gaming, and genetics. Because of the importance of one particular slime mold to so many research fields, the National Institutes of Health selected it as one of its model organisms for gene sequencing.

Moving at speeds up to 1 millimeter per hour, slime molds are slow-motion predators. They scavenge decaying organic material (like hardwood mulch) searching for bacteria and fungi to consume.

The slime may be ugly to some, but it is not harmful. Slime molds cause very little damage. Chemical control of slime mold is not possible. Frequent mowing and elimination of excessive thatch will help control slime mold in turf. Switching to a different mulch will control slime mold in landscape beds.

For more info about slime mold visit http://helios.bto.ed.ac.uk/bto/FungalBiology/slime.htm or http://www.uwex.edu/ces/wihort/gardenfacts/X1091.pdf

If you don’t have internet access, don't hesitate to call the Extension Office at 893-7533, write us at PO Box 1089, Lillington, NC 27546, or email me at gary_pierce@ncsu.edu

The plasmodium of Fuligo septica resembles scrambled eggs. Ironically, this plasmodium is gathered and eaten in Mexico. Usually the slime mold comes out at night and is collected by moonlight. The plasmodia are brought home, where they are mixed and eaten like scrambled eggs. How do you say “dog vomit slime for breakfast” in Spanish?

Gary L. Pierce

Horticulture Extension Agent

Harnett County