
To Zap Strawberry Foes, Scientists Seek
Methyl Bromide AlternativesBy Marcia
Wood November 3, 1999Root-nibbling microbes, currently
held in check by fumigating soil with methyl bromide, might threaten strawberry
plants in the future. Most uses of the fumigant--thought to damage Earth's
protective ozone layer--will be phased out by 2005. To help develop alternatives, Agricultural Research Service plant
pathologist Frank N. Martin at Salinas, Calif., is scrutinizing these microbial
enemies in greenhouse tests and at research plots in commercial strawberry
fields along California's central coast. California leads the nation's
strawberry production. Strawberry growers are a major user of the chemical. Martin has been evaluating the abundance and virulence of soil-dwelling
microbes called Pythium and Rhizoctonia, which cause a strawberry
disease known as black root rot. They also can infect lettuce, tomatoes,
cauliflower and many other plants. Martin's investigation is among the most extensive yet conducted of these
microbes in this key strawberry-producing region. The research provides details
that better equip scientists to devise new tactics for combating these pests.
Though black root rot doesn't kill strawberry plants outright, it may
significantly reduce yields. In the study, severity of plant symptoms varied
greatly. Pythium ultimum--the most prevalent Pythium at field
sites--and P. irregulare were among the Pythiums causing the most
damage to greenhouse plants inoculated with the microbes. But several other
Pythium species that were recovered caused few if any symptoms. All Rhizoctonia forms significantly reduced the growth of greenhouse
strawberry plants. Martin presented his findings at this week's
6th Annual International
Research Conference on Methyl Bromide Alternatives and Emissions Reductionin San Diego, Calif. More than 100 other scientific reports from other ARS
researchers throughout the U.S., as well as university and industry scientists,
are also being given at the conference. About 330 participants are registered to attend. ARS,
USDA's chief scientific agency, is a
conference sponsor. Scientific contact: Frank N. Martin, ARS
Crop Improvement and
Protection Research Unit, Salinas, Calif., phone (831) 755-2873, fax (831)
755-2814, [email protected] or at the
Methyl Bromide conference through Nov. 4, DoubleTree Hotel, phone (619)
297-5466. U.S. Department of Agriculture | |