University of Delaware Cooperative Extension, Kent Co., Commercial Horticulture Information: slime mold

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Saturday, September 5, 2009

Landscape - Current Pests

The following are some current pest problems in Delaware landscapes.

Septoria leafspot is one of several common diseases showing up now on flowering dogwood (Cornus florida) and silky dogwood (Cornus amomum). Some trees have numerous small angular spots on the lower branches that look like small dogwood anthracnose spots. It is too late for any chemical control.

This time of year we often see an increase of anthracnose on oak, maple and walnut. On oak and maple, look for large brown spots that follow the veins and some round spots as well. This late in the season no control is necessary. On walnut, the spots are irregular in shape, numerous and can cause premature defoliation. Again it is too late in the season for any control and the fungus does little to harm the health of the trees.

Puss caterpillars and other stinging caterpillars are actively feeding. Puss caterpillars have been found on Ilex and Acer.

Ground nesting wasps, yellowjackets, and hornets are active and becoming more of a nuisance as we approach fall.

Slime molds have been appearing on lawns especially after recent rains. Slime molds produce a gray growth over the blades of turf that give it a dark appearance from a distance. What you see is the reproductive stage of this primitive fungus. It is not harmful to turf and can be removed by cutting the grass. These are related to the slime molds that appear in mulched beds as white, pinkish red, and yellow blobs often referred to as the “dog vomit fungus”.

Information from the current issue of the Ornamentals Hotline newsletter from the University of Delaware Cooperative Extension.

Tuesday, June 23, 2009

Landscape - Wet Weather Nuisance Fungi

Wet weather means nuisance fungi are appearing in turf and landscapes. The following is more information.

The rains are producing calls about slime molds, stink horns, puff balls, and other mushrooms in mulched beds and turf. All of these fabulous fungi are just a nuisance--not pathogenic to plants in these beds or turf. Just rake them out or spray the slime molds with a hose to remove them. They are utilizing the organic matter present as a food source and are doing what comes naturally to them, decomposing and recycling organic matter.

Slime Mold in Turf

Wednesday, October 1, 2008

Turf - Slime Mold

The following are pictures of slime mold that is showing up on turf now due to the recent wet weather. It is superficial and will not harm the turf. Mowing will break it up and disperse it so it does not cover the turf.

Photos by Gordon Johnson, Extension Horticulture Agent, UD, Kent County

Tuesday, July 15, 2008

Landscape - Dog Vomit Slime Mold

Landscapers may be called to identify unusual growths in landscape beds. These are often slime molds. The following is an article on the Dog Vomit slime mold.

There’s been a bumper crop of slime molds in landscape beds this year, and we’ll see them throughout the summer and into the fall. By far the species most often noticed is Fuligo septica, a.k.a. the “dog vomit” slime mold. Despite the unpleasant name, it is completely harmless to humans, animals and plants.

Slime molds spend most of their lives as amoeboid cells or inconspicuous plasmodia that creep slowly through soil, leaf litter, mulch, etc. A plasmodium feeds by engulfing bacteria, spores, and bits of organic matter. It eventually moves out to a more exposed location on top of mulch, pine straw, a stump, a low-growing plant, or even the foundation of a building. There it stops moving and transforms into a fruiting (spore-producing) body. This is when Fuligo septica first gets noticed as a bright yellow, frothy mass (image by M. J. Munster) a few inches to up to a foot in diameter. It quickly fades to a dull orange (image by M. J. Munster) and then a light tan as its surface dries to a crust (image by M. J. Munster). After a few days it breaks apart to release its dark-colored spores, which blow away to start the life cycle anew. Within a week or two, all that’s left is a dusting of leftover spores and bits of gray or yellowish crust.

Control measures for Fuligo septica are neither effective nor necessary. If considered intolerably unsightly, they can be removed by hand or washed off with a hose, but there's a good chance that new ones will pop up at a later date, though probably not next year, unless new mulch is applied.