Introduction
Many people are concerned by the tiny dark spots they
find on their houses, cars, and plants. Often the spots
are mistaken for scales. The spots may actually be spores
from members of a group of fungi commonly called the
"shotgun" or "artillery" fungi in the
genus Sphaerobolus. These fungi colonize dung or
other organic matter such as wood mulch, wood benches,
wood sheds, etc.
Artillery fungi use an interesting mechanism to disperse their spores.
Dark brown spore packets, called peridioles, sit on top of specialized
cup-shaped cells which accumulate water and cell contents. When enough
liquid is accumulated, the cupped cells invert causing the cells to
burst and propel the peridioles as high as 6 meters where they can
adhere to new surfaces.
Symptoms
The fungi appear as yellow-brown to black, disk-shaped
spots of about 1-2 mm. They can be found on nearly any
surface due to a sticky substance (i.e. Mother Nature's
version of 'super glue') covering the peridiole that
allows for good adherence. The fungi are very sensitive
to light and the spores are projected towards it, so they
are frequently located on white and light-colored
substances (house siding, white cars, etc.) or other
bright, light-reflecting bases.
Figure 1: An artillery fungus spore packet within
the cup. (provided by the Plant
Disease Diagnostic Clinic, Cornell University.) |
Figure 2:
Artillery fungus spore packets stuck on the vinyl
siding of a house. (provided by the
Plant Disease Diagnostic Clinic, Cornell
University.)
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Management Strategies
Artillery fungi spores do not normally structurally damage the houses,
cars, plants, etc. they cover. Removing the fungi is virtually impossible.
Scrubbing and scraping with tools or washing with soap and water aids
somewhat in removal; however, the use of tools or harsh chemicals
may damage painted or otherwise colored surfaces. No fungicide treatment
is recommended at this time.
Lately, the appearance of Artillery fungi has been associated with
wood mulch (versus bark mulch) and the increased use of wood products
in potting media. Composting of these products prior to incorporation
into media is encouraged to prompt the growth of beneficial antagonistic
organisms. Also, the use of gravel mulch, stone, pea gravel, and black
plastic next to buildings instead of using wood products will help
reduce the problem. If wood products are used, the addition of about
3 cm of fresh mulch to cover old mulch each year may lessen the problem.
Use of bark products, rather than wood products, may also lessen the
fungal spread.
One word of warning to homeowners wishing to replace house siding
splattered by Artillery fungi --- insurance companies may not cover
claims of damage due to "molds".
Created, KLS, 08/02
This publication contains pesticide recommendations. Changes in pesticide
regulations occur constantly, some materials mentioned may no longer
be available, and some uses may no longer be legal. All pesticides
distributed, sold, and/or applied in New York State must be registered
with the New York State Department of Environmental Conservation (DEC).
Questions concerning the legality and/or registration status for pesticide
use in New York State should be directed to the appropriate Cornell
Cooperative Extension Specialist or your regional DEC office. READ
THE LABEL BEFORE APPLYING ANY PESTICIDE. __________________________________________________________________________________
The Plant Disease Diagnostic Clinic
at Cornell University is located at 334 Plant Science Building,
Ithaca, NY, 14853. Phone: 607-255-7850, Fax: 607-255-4471,
Email: kls13@cornell.edu
or slj2@cornell.edu
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