A fungus among us

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Recent rainfall has led to explosion of mushrooms in lawns and mulched areas throughout our area. Most of these fungi are completely harmless, though many of them are annoying. While mushrooms are easily recognized by most people, some of their relatives that can be found growing on hardwood mulch may not be as familiar. From time to time, some of the more noticeable of these organisms may catch a gardener’s attention and cause them to wonder about their identity.

Slime mold, one of the most eye-catching mulch-inhabiting fungi, is often commonly referred to as dog vomit. This mat-like growth usually begins as a small area a few inches across but can rapidly grow to up to 3 feet in diameter and may be bright yellow or orange, fading to brown and tan as it dries. Slime molds do not harm plants and usually dry up within a few days of forming. One of their more curious characteristics is that they are actually able to move, up to 2 or 3 feet a day. If their appearance is offensive, they can be scooped up and added to the compost or thrown away.

The stinkhorns are a group of mushrooms most people smell before they see. The octopus stinkhorn is one of the most common and putrid, emitting the odor of decaying flesh. The name octopus stinkhorn is very descriptive of this curious mushroom, which looks like an orange octopus or squid popping up out of the mulch. Like all mushrooms, removing just the visible growth does not get rid of the fungus because the majority of its body is left behind.

Though the appearance or odor of some of these fungi is sometimes considered to be a nuisance in home landscapes, they are harmless. No fungicides are available for mushroom control. Nuisance fungi are most common on hardwood bark mulches and wood chips as well as in yards where trees have been removed. When trees are removed, much of their root system is left behind to decay, providing an ample source of nutrition for mushrooms.

There are some steps that can be taken to minimize the occurrence of nuisance fungi. Fresh wood chips or sawdust should never be used in the landscape but should instead be allowed to age at least six months or be composted thoroughly before using as a mulch or soil amendment. If nuisance fungi are causing a problem in your landscape, switch from hardwood mulch to pine bark mulch or pine straw. Watering hardwood mulch well when it is first applied can discourage the growth of nuisance fungi.

There is little that can be done to eliminate nuisance mushrooms from yards and fungi and mold from landscape mulches. Simply allow nature to run its course and wait for these growths to disappear, which usually occurs within a few days.

If you have questions about gardening or landscape care, contact the Wilson Extension office at 252-237-0111.