Homegrown column Sept. 05, 2009
Help. There’s this awful looking thing growing along the ground in my garden that looks like The Blob, only yellow. What is it? Do I need to start packing? Is it going to eat up my house?
Actually, what you have is a cool little organism called a slime mold. Slime molds aren’t really fungi; they’re their own little unique thing. They have some characteristics of fungi, some of plants, some of bacteria and even some of animals.
Most of them spend most of their lives as tiny single-celled amoeba-like organisms that swim around in moist environments, feeding on bacteria and other microorganisms. Occasionally, these miroorganisms fuse together. What you’re seeing is actually an enormous single cell with millions and millions of nuclei from the individuals that fused into a single organism. This “super cell” actually moves (up to an inch a day—so don’t stand in one place too long). Slime molds have demonstrated the ability to “remember” repetitive conditions and react even though they don’t have a brain. Its main job is to produce spores. Before too long, your bizarre yellow gob of goo will dry up and turn brown. If you disturb it, it will give off a cloud of brown or black spores that look like dust.
Slime molds aren’t harmful to plants or animals. They just look gross. They actually are a part of the very beneficial soil ecosystem that allows plants to grow successfully. The only damage to plants they occasionally cause is by covering and shading them. Controlling them consists of shoveling the blob up and throwing it away or breaking it up with a hard spray of water. You can even opt to do nothing but either way, they’ll disappear in a week or two.
Last fall I was obliged to have a very large old cottonwood removed, as it was diseased. We had the stump ground, leaving about 8-foot diameter crater. This year numerous root runners are providing shoots all over the yard, and the stump is a haven for new cottonwood shoots as well.
I have drilled into the stump area with a 12” bit and poured saturated salt solution into the bore holes and am spud-barring the scattered shoots across the yard — all of this seems ineffective, requiring much effort so far. Any recommendations? I would like to keep the stump area arable in the future; is a ground cloth and soil-over a good approach? What of the pesky root runners?
— Jim Merci
The best way to go after the stump is with a stump killer containing the herbicide Triclopyr.
Fertilome makes a product called Brush and Stump Killer, which contains it. I’d probably start by killing the stump. Drill some new holes like you did with the salt but drill them in a circle just inside of the bark. You need to drill down deeply enough to get into fresh, living tissue.
Fill the holes with undiluted Brush and Stump Killer. It will absorb into the vascular tissues of the plant and move out and kill the roots.
Doing this will eventually kill the sprouts as the roots beneath them die. If those sprouts are getting out of hand, you can go after them directly with the same product. If the sprouts are pretty thick (say three-quarters of an inch in diameter or bigger) you can cut them off and carefully paint the freshly cut end with the undiluted Brush and Stump Killer.
If they’re smaller, there are directions on the bottle to mix the concentrate with water and spray the foliage. Whatever way you decide to go, be careful with this stuff — it’s pretty potent. Try to keep it just on the plant and avoid wetting the soil. Soil that’s soaked with the concentrate can be sterilized for a year or longer. It can burn the lawn when you’re spraying the sprouts, but the lawn will recover just fine as long as it doesn’t get soaked. You don’t have to be afraid of this stuff. Just go slowly and carefully and use some common sense.
If you don’t want to go that way, I’m afraid the only other way I know of to deal with the problem is to physically dig up the stump (probably a job for a backhoe) and the roots that the suckers are coming from.