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Note from landscaping: Thank you very mulch

Mulch does more to help than hinder.

Date published: 3/30/2007

John E. Howe is an agent in Virginia Cooperative Extension's Spotsylvania County office specializing in animal science. Phone 540/507-7571; e-mail
Email: jhowe@vt.edu.

MULCHING land- scape beds is a normal springtime activity. Mulch is any material used to protect the soil surface, and can be either organic or inorganic.

Nature provides mulch in the form of needles, bark, flower blossoms, fruit and other organic materials, then we supplement it. It helps prevent moisture from evaporating and keep weeds in check. Erosion is reduced, as is exposure to soil-borne diseases. As organic mulch decays, nutrients are added to the soil.

Along with the benefits of mulch there are downsides, such as when microorganisms in the mulch cause problems. Slime molds, plant diseases, toad stools or mushrooms and artillery fungus are common issues.

Slime molds are bright yellow or orange masses a few inches to a foot or more in diameter. This fungus is unsightly but harmless. Toad stools or mushrooms are fungi, some of which may be toxic to humans and ought to be removed as a precaution.

Artillery or shotgun fungus causes the little black spots found on house siding or cars. These one-tenth-inch specks are spore masses called gleba, and are difficult to remove. The term artillery reflects the fact that the fungus uses energy to shoot the gleba much like a cannon fires artillery rounds--up to 20 feet away.

The artillery fungus shoots the spore masses towards light. Lacking sunlight, gleba are shot towards reflective surfaces such as white siding and cars.

There are no fungicides registered or approved for the control of artillery fungus, so chemical controls are out. Since the problem is associated with organic mulches, managing or changing the mulch used can help. Replacing organic mulch is another option. Gravel, landscape cloth and mulches made from recycled tires will not support fungal growth, but they might not provide a preferred appearance.

Otherwise, there are three alternatives: Spade the existing mulch into the soil and apply a new layer; remove the existing mulch and replace it with a layer of new mulch; or simply cover the existing mulch with new layer. The latter will help only until the new mulch is colonized by the nuisance fungus.

For established plants, apply mulch in early spring prior to weed germination. For new plantings, apply mulch right after planting. Mulch layers should be 2 to 3 inches deep. Keep mulch at least 3 inches away from stems or trunks of woody plants. Benefits: Helps landscape and environment by reducing water loss from evaporation, suppressing weed growth, reducing erosion, improving the soil's condition, and by making landscape beds look good. Problems: Can be a source of fungus and disease.

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Date published: 3/30/2007