Last week I received a text from my son that included a photo of brown spots in his lawn. Being a brand new homeowner (and now having to take care of a lawn), he was concerned about these spots and wanted to know what he should do.
He was seeing the results of a disease called red thread. The pathogen that causes red thread is very active in spring and fall when temperatures are cooler (between 40 and 70) and there is heavy dew. We recently had cooler nights and have had heavy dews, leading to the outbreak.
The good news is that red thread doesn’t usually kill a lawn and the condition will disappear when temperatures warm up at night.
Red thread appears as pinkish-tan patches in the lawn that are about 4-8 inches in diameter. The symptoms are similar to dollar spot and other lawn diseases except for one main difference — the pathogen that causes red thread produces reddish, thin thread-like structures at the tips of the grass blade. These structures are called sclerotia and are very noticeable when red thread begins to develop.
Red thread tends to develop in Kentucky bluegrass, perennial ryegrass and tall fescue turf that is low in fertility. One recommendation is to follow a regular fertilization program to keep the turf healthy.
Another common problem appearing at this time is one of the slime molds called dog vomit fungus. If you see this in the landscape you will understand why it’s named dog vomit fungus. It looks just like its namesake.
This is not really a true fungus, but rather acts like a plasmodium (parasitic protozoa) that is a predator in the decomposition process of hardwood mulch. We see this a lot in mulches that are composed of a lot of ground up hardwood pallets.
The massive blob of yellowish goo is actually the reproductive structure that forms during the right weather conditions. These structures produce lots of spores that are eventually released.
Dog vomit fungus doesn’t really cause problems in the landscape other than the fact that it just plain doesn’t look good. One method of control is to keep the mulch stirred up to prevent the mass from forming.
The other thing is to gently pick it up with a pitchfork or shovel and bag it and toss it in the trash. Remove the mass when it forms and before it releases spores. Don’t spray it with water as the spores will spread.
There are numerous types of slime molds and they are not toxic or harmful to plants. However, they can look a little disgusting in the landscape, especially this one.