Horticulture Hotline 07/13/20
By Bill Lamson-Scribner
Many people are coming in to Possum’s with pictures and
texting me pictures of a black film over the leaf blades of grass. What you see
is the fruiting body of a fungus that is decomposing thatch and other organic
matter in the soil. When the fungus tries to reproduce, it sends it’s spores up
the leaf blade of the grass where it is higher up in the air, so the wind will
catch a spore more easily. With the spore up in the air, it will travel further
also. This fungus is called slime mold. Very nasty looking, but beneficial
since it is helping to control thatch.
Slime mold does not hurt the grass, except for the shading
of the sun from the leaf surface where photosynthesis takes place. This shading
is usually not an issue because these spores disappear very quickly. The
weather was perfect for this mold to want to reproduce. Overcast, rainy and
humid days are ideal conditions for this fungus.
Since slime mold’s
main purpose is to decompose organic matter in the soil and it really does not
damage the grass, I have never recommended any chemical control for slime
molds. I do suggest you spray it off of the leaf blades of your grass with a hose
if you can’t stand it. In a commercial setting or golf course (read and follow
product label), you could use Protect DF.
All grasses are a susceptible host, but remember the spores
are just using the grass like a ladder for a little elevation. Slime mold is
helping to break down thatch and other organic matter, which is a good thing. I
would leave it alone and let mother nature lend me a hand in controlling thatch.
I know I have to get back to those biting insects, but the
rains we had and basically the time of year, brought up a whole different set
of issues. Gray leaf spot on St. Augustine grass, chinch bugs, army worms,
large flying roaches trying to get out of the heat at a cousin’s house (no one ever
has roaches themselves – always a friend or a cousin), and those nasty flies by
the grill (s) and garbage cans have come on strong.
With all the rain and the fact that many people just
fertilize in the spring because they do not realize how long our growing season
is, I’m seeing some mighty hungry grass, shrubs and trees.
Always read, understand and follow product label. The
product label is a Federal Law.
