Biofumigation Research and Soil-Born Disease Control in Kentucky

Biofumigation studies

Southern SARE logoBackground

Paul and Alison Wiediger know how to grow food in harmony with nature. For more than 10 years they have offered their customers in Bowling Green, Kentucky, a constant supply of fresh, locally-grown vegetables. They don't use synthetic fertilizers, pesticides, or even heat; only the sun warms the plastic hoop houses that protect their crops in the depths of Kentucky's winter.

Their mesclun mix -- a blend of baby lettuce leaves and spicy greens -- is particularly popular in winter. But Paul and Alison had a problem: Patches of young lettuce plants started dying before harvest. As time went on, the problem got worse.

The culprit was a fungus, Sclerotinia sclerotiorum, which causes a disease called white mold. The cool, moist conditions in the Wiedigers' solar greenhouses in winter were perfect for white mold infection. The growing fungus would deposit hard black bodies, called sclerotia, on the soil surface. Some sclerotia would quickly sprout into tiny mushrooms that spread millions of spores throughout the greenhouses, infecting even more lettuce plants. Others would settle into the soil, where they might sit for years before sprouting mushrooms or infecting plant roots.

Paul Wiediger and Paul Vincelli survey a bed of lettuce infested with white mold Sprouting sclerotia
Farmer Paul Wiediger (left) and University of Kentucky scientist Paul Vincelli (right) inspect a bed of young lettuce plants infested with white mold, caused by the fungus Sclerotinia sclerotiorum. Michael Bomford photo. Hard black fungal bodies, called sclerotia, sprout into tiny mushrooms that spread S. sclerotiorum spores. Spores infect leaves; the fungus can also grow directly from sclerotia, infecting plant roots. Ed Dixon photo.

A University of Kentucky plant pathologist, Dr. Paul Vincelli, visited the Wieidgers' farm and diagnosed the problem. He recognized that the conventional solutions -- synthetic fungicide application or soil disfestation with toxic fumigants -- would not be acceptable to the Wiedigers, who were among the first Kentucky growers to certify their land as organic. Nonetheless, he thought he might have a solution.

Researchers and farmers in Australia have had success fighting S. sclerotiorum, and some other soil-borne diseases, with mustard plants. Members of the mustard family produce remarkable chemicals called glucosinolates, which have excited scientists' interest for two reasons: They may help protect humans from cancer, and they act as natural fungicides. Vincelli wondered if mustard cover crops could be used to protect vegetable crops in Kentucky from soil-borne diseases like white mold.

Vincelli contacted Dr. Michael Bomford, a Kentucky State University researcher, specializing in organic vegetable production, who had worked with the Wiedigers in the past. Together with KSU chemist Dr. George Antonious they developed a series of laboratory, greenhouse, and on-farm experiments to test the potential of mustards to combat soil-borne disease in Kentucky. Their work is funded by the Sustainable Research and Education (SARE) program of the United States Department of Agriculture.

Project participants

Kentucky State University University of Kentucky Farmer cooperators Advisory council
Michael Bomford
George Antonious
Tony Silvernail
Brian Geier
John Rodgers
Paul Vincelli
Kenneth Seebold
Ed Dixon
Amy Bateman
Paul Wiediger
Alison Wiediger
Joseph O'Daniel
Eric Walles
Kim Cowherd
Keenan Bishop

Project links

Last updated January 31, 2008

College of Agriculture, Food Science and Sustainable Systems