To Guard Mums, Spice the Fungi By
Cut chrysanthemums are a traditional winter bouquet. But florists
and nurserymen must guard these fragrant flowers against fusarium
wilt, and the primary means of protection--fumigation with methyl
bromide--will be banned in the year 2001 under guidelines of the Clean
Air Act. Spices such as hot peppers may provide an alternative.
Researchers with the
Arboretum's Floral and Nursery Plants Research Unit have found
that extracts made from hot peppers and cloves send the pathogen
packing. The arboretum is part of USDA's
Agricultural Research Service.
The Society of American Florists estimates that 57 million
chrysanthemum blooms and 100 million pompons--the smaller flowers used
in bouquets--were sold in 1995. Making sure these flowers are healthy
protects an important market.
In laboratory studies, ARS scientists treated soils with extracts of
clove and cassia tree. They also tested a mixture of chili pepper
extract and essential oil of mustard.
The chili pepper mixture knocked out 99.9 percent of the fusarium
populations. Although clove and cassia killed less fungus--97.5
percent and 96.1 percent, respectively--they maintained their
fungus-suppressing power longer than the pepper.
The scientists hope to devise a two-step strategy: first adding the
spices to the soil to kill fusarium, then introducing friendly
microorganisms to crowd out any fusarium that survive the spicy
Scientific contact: James C. Locke, ARS
and Nursery Plant Research Unit Beltsville, Md., phone (301)
504-6413, fax (301) 504-5096, firstname.lastname@example.org.