By Melody Kendall

Yesterday, while I was walking in my garden eating my fruit and yogurt breakfast, I noticed an object under my lace leaf maple (Acer palmatum).  Upon closer inspection I almost lost what breakfast I had consumed.  When I had watered the previous night that yucky, slimy mass had not been there.  What was it? 

When I poked the mass with a stick it had a foamy consistency and a semi-hard crust. My first thought was that the dog had had digestion issues and the base of the tree was the recipient of that upset. Then the light dawned, this was the famous dog vomit fungus that I had heard about from various sources in my circle of gardening friends.  I'm here to tell you that the name fits this fungus or slime mold perfectly.

The dog vomit slime mold (Fuligo septica) is actually a type of slime mold, not a fungus. Analysis of the slime mold's DNA has revealed that it has been on earth for around a billion years, before plants and animals. The slime mold has many of the characteristics of an amoeba.  A true fungus has a cell wall and breaks down its food with enzymes before absorbing it, where an amoeba absorbs the food source and then breaks it down.  The dog vomit slime mold follows the amoeba's digestion method.  In its first plastid stage it creeps like a blob over dead wood and other materials, moving about a millimeter per hour.  When ready to reproduce it makes spores that blow away to start new plasmodia elsewhere. It's very creepy, no pun intended.  

This slime mold feeds on decaying plant matter. The moist compost and wood chips under the maple made an ideal condition for this visually repugnant mold to thrive and grow very fast.  Considered a nuisance fungus, not a disease, the mold is mostly beneficial as it breaks down organic matter and releases the nutrients for plants to access. Though it might be an allergen to susceptible people it is not toxic to humans, plants or pets. Appearing almost overnight the light-yellowish colored mold is sometimes called scrambled egg slime because of the color and the consistency of the mass.  It's not classified as edible and in my opinion the moniker “dog vomit” does a good job describing this clump of yuckiness. 

Upon study, scientists have found that these slime molds have the potential for use in antibiotics and fighting cancer. Even more exciting is the possibility of its use as an environmental site remediation component because of the slime mold's ability to hyper-accumulate toxic heavy metals and convert them into inactive forms.

Though the dog vomit slime mold is not harmful to my plants the look of it made me want to remove it pronto!  When I scooped out the mass, I was well aware that spores spread easily and can survive for years, but at least I would not have to look at the fruiting body marring my landscape today. 

Master Gardeners are following recommended social distancing guidelines that keep everyone safe, Napa Master Gardeners are available to answer garden questions by email: mastergardeners@countyofnapa.org. or phone at 707-253-4143.  Volunteers will get back to you after they research answers to your questions.

Visit our website: napamg.ucanr.edu to find answers to all of your horticultural questions.

Photo credit: Mel Kendall

References:

Missouri Botanical Garden- Lace Leaf Maple

https://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=c564

UC IPM-Nuisance fungi http://ipm.ucanr.edu/TOOLS/TURF/PESTS/disnusiance.html

UC Davis edu-blog-Dog Vomit Fungus http://ceventura.ucdavis.edu/?blogpost=24159&blogasset=109383

UF-IFAS-'I ain't afraid of no Slime Mold-Molly Jameson

http://blogs.ifas.ufl.edu/leonco/2018/09/18/i-aint-afraid-of-no-slime-mold/