May Lead to Better Control of Gray Mold
By Kathryn Barry
September 11, 2001
Gray mold (Botrytis
sp.) reduces yield, softens fruit, or affects color in a wide range of
small fruit, grape and nursery crops. In the Pacific Northwest alone, the mold
causes up to $125 million per year in crop losses.
Agricultural Research Service
scientists at the agencys
Crops Research Laboratory in Corvallis, Ore., and researchers at
Oregon State University in Corvallis, have
discovered one previously unknown reason for the molds success. They
found that the mold can live as an epiphyte.
That means mold spores germinate and grow unnoticed on the surface of leaves
and other plant parts, drawing nutrients from plant surfaces without damaging
the plant. Mold can thus be present constantly until the perfect conditions
arise to infect the plant and cause disease.
The mold spores can move from leaf hair to leaf hair, allowing the mold to
spread quickly and to come into less contact with pesticide residues on the
If researchers can determine the conditions that allow the mold to live in
this epiphytic state, they may be able to develop new strategies to control the
mold, according to ARS plant pathologist Walter F. Mahaffee at the Corvallis
Currently, growers use fungicides and biological control agents to keep the
mold in check. But Botrytis can quickly develop resistance to
fungicides. And currently available biocontrols can help prevent infection, but
they don't get rid of the mold once it is established.
The researchers recently found a new bacterium that may lead them to better
controls. Although the bacterium itself is not a good candidate, it produces
compounds that may be able to be harvested or replicated in the laboratory to
produce a more effective chemical control.
A story on this research appears in the
issue of Agricultural
Research, the agencys monthly magazine.
ARS is the chief scientific research agency of the
U.S. Department of Agriculture.