Ag Notes: Fungi can be a nuisance on mulch

June 15, 2004|JERRY LITTLE

I'm reviewing several calls at the office asking about the fungus problems with mulch.

Mulch has many benefits around plant beds, foundation shrubs and other gardening locations in the yard. However, nuisance fungi occasionally grow on mulch applied to landscape plants and trees.

In landscape beds and gardens, mulch helps control weeds, prevents extreme soil temperature fluctuation, decreases water evaporation and improves drainage.

Mulch also reduces mower and string trimmer damage by suppressing vegetation near shrubs and trees. As it decomposes, mulch produces organic materials to improve soil and otherwise benefit plants.

You need to periodically re-apply mulch to continually receive these benefits.

Nuisance fungi occasionally grow on mulch. They include shotgun fungus, slime molds, stinkhorns, earth stars, toadstools, and dog vomit fungus.

The shotgun fungus shoots masses of tiny black spore structures onto adjacent surfaces such as vehicles and home siding.

Slime molds are more unsightly than harmful. They don't cause plant diseases and aren't parasitic. Slime mold spores usually appear from late spring to autumn.


Abundant wet weather stimulates above-ground appearance of these fungi that initially appear slimy but quickly become dry and powdery when converting into spore masses.

Slime molds often quickly appear and usually disappear in one to two weeks. They tend to reproduce in the same location every year.

Fungicide use isn't recommended because slime molds aren't harmful.

When mulch hasn't been composted, it might contain fungi that cause plant diseases. However, this situation is rare and only occurs in non-composted mulch.

Plant material fertility problems can arise when fungi in decomposing mulch remove nitrogen from the soil.

Insufficient moisture problems can develop when fungi permeate thick layers of dry mulch creating a surface that's difficult for water to penetrate.

To gain the most benefit, use composted mulch with a high bark content and little wood material.

Avoid finely-ground, woody products that haven't been composted.

If you buy fresh wood chips from a tree-maintenance firm, add water to the chips and allow them to partially compost for about six weeks.

If this material doesn't have fresh leaves, add some nitrogen to speed up the process.

Avoid using fresh or partially composted wood chips near the house foundation because they can provide a food source for termites.

Immediately after you put mulch around plants or trees, soak it with water to enhance bacterial activity to initiate decomposition.

Periodically wet mulch during the growing season.

Avoid soured mulch because it tends to injure plants. You can spot sour mulch by its bad odor.

For more information, contact the Boyle County Cooperative Extension Service.

How's my mule?

An old man was leaving from a fair he had just attended. He had brought his mule for a show and so was taking him home as well.

A few miles down the road, the old man's neighbor spotted him walking down the road and stopped to speak to him He asked why the old man was walking and would he like a lift.

The old man had blisters and sores on his feet from being on them all day and gladly accepted the ride home.

The neighbor told the old man to tie the mule to the fence and hop in the truck and that he would pick the mule up later.

To this, the old man objected. "My mule will be just fine tied to the bumper of your truck."

The neighbor wasn't sure that this was a good idea, but the old man reassured him and tied the mule to the bumper.

The two men got into the truck and started down the road. The neighbor was cruising down the road at 25 mph when the old man turned and asked, "How's my mule doing?"

The neighbor looked back and said, "He's doing fine, just like you thought."

Since the mule was doing just fine, the neighbor thought he would step up the pace just a bit and sped up to 35 mph.

The old man looked back and asked, "How's my mule doing?"

The neighbor looked back and said, "He is keeping up and doing fine."

The neighbor thought he would have some fun and kicked the truck up to 50 mph down the road. The old man again asked, "How's my mule doing?"

The neighbor looked back again and said, "Well he is keeping up, but his ears are laid back, his eyes are wide open and his tongue is hanging out of his mouth."

The old man asked, "Which side of his mouth is his tongue hanging out, the left or the right."

The neighbor looked back again and said, "The left side. Why?"

The old man smiled and said, "Hold on, because that means he's getting ready to pass."

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