Can Soil Microbes Rescue
Strawberries and Peaches from Disease?
March 12, 1997
Scientists are looking for a few good microbes to patrol the soil in
strawberry fields and fruit orchards. Natural bacteria would help plants resist
diseases such as black root rot, or a condition known as replant disorder.
The search is a joint effort of scientists with
USDA's Agricultural Research Service, at Fresno,
Calif., and a commercial firm, Gustafson,
Inc., in McKinney, Texas. If the scientists succeed, growers may be able to
reduce reliance on chemicals such as methyl bromide needed to kill disease
organisms in the soil.
Black root rot occurs when certain soil fungi attack the roots of strawberry
plants. It's one reason why strawberry growers fumigate fields with methyl
bromide before planting. Growers of peaches and other stone fruits fumigate to
prevent another problem--replant disorder. It occurs when peach or other stone
fruit trees are removed, and the "replacement" trees don't thrive.
Some strains of rhizobacteria--soil-dwelling microbes--are known to secrete
compounds that bolster disease resistance and increase plant growth. But no one
knows exactly how the compounds do this.
Under a cooperative research and development agreement, ARS researchers will
evaluate microbes provided by Gustafson. They want to discover which
rhizobacteria strains might be the best soil allies of strawberries or stone
Top-performing strains may become candidates for commercial development by
Gustafson. Research elsewhere has shown that the test strains promote growth of
some vegetable crops. The idea of using rhizobacteria to protect crops is not
new. But rhizobacteria that would do this job for strawberries or stone fruits
have not been commercialized.
Scientific contact: Cynthia G. Eayre, USDA-ARS
Research Laboratory, Fresno, Calif., phone (209) 453-3162,