Certified Since 1978
"Our service stops when our customer stops calling"
Certified Since 1978
175 Strafford Ave. Suite 1, Wayne,
PA 19087
610-964-1477
Serving Montgomery, Chester, Delaware,
Phila. &
Lower Bucks Co's. in Southeastern PA.
Black spots on houses: beware of the mulch
Nurserymen, landscapers and greenhouse operators are occasionally contacted by homeowners seeking the identity of small black spots spattered on leaves of ornamental plants, siding, downspouts, soffits, and windows of their homes. Under certain conditions, nurserymen and greenhouse operators may themselves find the spots in their operation. Attempts to remove the spatters are generally futile, and identification of the source is then sought. The black spots often are mis-indentified as scale insects or insect excrement. The spots do slightly resemble miniature soft scale or common fly speck. They are 1-2 mm in diameter and slightly raised to glebular. The outer coating is actually brown and darkens with age. When scraped open, the center is found to be off white, finely granular and gummy. These black spots actually have nothing to do with insects, but are masses of mature spores expelled from fruiting bodies of the Sphaerobolus stellatus tode. A relative of the bird's nest fungus, it is commonly called artillery fungus by mycologists.
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Life History: The spherical fruiting is approximately 2 mm in diameter and produces spores internally. When mature, it splits radically from the apex, forming 4 - 8 teeth along the outer rim of the now cup-like structure. The round mass of spores , known as global mass, is about 1 mm in diameter and rests I liquid at the bottom of the cup. The tissue layers in the fruiting body have separated by this time, and remain attaches only to the teeth. Approximately 5 hours after opening, the inner cup is violently everted, catapulting the glebal mass into the air. The everted inner cup can be seen as a pearl-like projection. The Sphaerobolus discharge mechanism, estimated to generate 1/10,000 hp can throw the glebal mass up to 6 m (18 ft). The fruiting body is strongly phototropic, and the glebal mass is generally shot towards the strongest source of light. Out doors, this will be the sun or even highly reflective surfaces, such as glass and light colored walls. |
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Substrates: Sphaerobolus stellatus grows on dung and well rotted wood such as tanbark and wood chips used as foundation bed mulches. It prefers open areas with little shade and sufficient moisture. In Pennsylvania, the fungus most frequently found on the northwestern exposure of home, but has also been reported growing on old benches in greenhouses and even indoors in mulches potting plants, where it spatters glebal masses on walls, draperies and windows. With sufficient light, the optimum temperature range for the production of fruiting bodies is 10-20 degrees C (50-68 degrees F). Because no fruiting bodies are produced above 77 degrees F, the problem is limited to spring and fall. |
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Control: Fungicides have not been evaluated for control of this fungus. For those locations plagued with the problem, an alternate form of mulch for foundation beds may be in order. Yearly addition of fresh, treated tanbark or wood chips may lessen the problem if all the old mulch is completely covered. However, scraping glebal masses from windows and walls will possibly re-infest beds because the spores contained in the glebal masses have been reported to be viable for up to 11 years. In greenhouses and other areas where spaerobolus stellatus is growing on rotted wooden structures, replacement of the rotted wood, coupled with good sanitation, would eliminate the fungus. |
Rayanne D. Lehman Entomologist, Pennsylvania Department of Agriculture,
Penn State University,
College of Agriculture, Neshaminy Manor Center,
Doylestown, Pa. 18901
There is no product that has been proven to remove the
spots from walls,
except scraping and washing clean.
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