State tomato producers and home gardeners should be on the lookout for a devastating disease of tomatoes – late blight. Not seen in Tennessee since 2009, late blight can strike tomato or potato plants with sudden severity, said Steve Bost, a plant pathologist with University of Tennessee Extension.

“The more common blight diseases of tomato, early blight and Septoria leaf spot, develop more gradually,” Bost said. “The late blight pathogen, however, can strike suddenly. It enters a garden on infected transplants or by spores arriving on air currents from other areas. Mild, rainy weather favors production and spread of the spores among plants.  In severe cases, all tomato plants can be totally destroyed.”
In a recently published fact sheet by UT Extension, Bost describes how producers and gardeners can identify late blight.  The publication, Foliar Diseases of Tomato (UT Extension SP- 277-W) is available online free of charge at the UT Extension website: 
Simply enter the publication number or title into the search engine.
The fact sheet includes color photos of late blight as well as tomato diseases including Septoria leaf spot, gray mold, leaf mold, and bacterial spot, bacterial speck and bacterial canker.
Bost adds that plants can be protected from late blight with sprays of fungicides containing chlorothalonil, available at garden centers under several brand names. Organic gardeners can use copper fungicides. “Hot, dry weather stops the spread of this disease,” he said.
For more information about tomato or other vegetable and fruit production go online to the UT Extension publications website or contact your local county UT Extension office.

UT Extension provides a gateway to the University of Tennessee as the outreach unit of the Institute of Agriculture. With an office in every Tennessee county, UT Extension delivers educational programs and research-based information to citizens throughout the state. In cooperation with Tennessee State University, UT Extension works with farmers, families, youth and communities to improve lives by addressing problems and issue at the local, state and national levels.



Dr. Steve Bost, 615-832-6802,



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