The most common disease of tomatoes in Tennessee is early blight, also called Alternaria leaf blight. Dr. Steve Bost, a plant pathologist with University of Tennessee Extension, says the disease is caused by the fungus Alternaria solani.
“The fungus causes a leaf blight and may cause seedling disease, collar rot, stem canker or fruit rot,” Bost says. The early blight fungus is spread by wind and splashing rain, and outbreaks are favored by warm, rainy weather. The fungus overwinters in crop debris and on seeds and can survive between crops on solanaceous crops and weeds, he adds.

In a recently published fact sheet by UT Extension, Bost describes how producers and gardeners can indentify early blight and lists control measures for the foliar disease. The publication, Foliar Diseases of Tomato (UT Extension SP- 277-W) is available online free of charge at the
UT Extension publications website:

Simply enter the publication number or title into the search engine.
The fact sheet includes color photos of early blight as well as late blight and other tomato diseases including septoria leaf spot, gray mold, leaf mold, and bacterial spot, bacterial speck and bacterial canker.
Bost reminds gardeners that the best way to prevent foliar diseases is to choose resistant varieties and to shop locally. “Purchasing transplants from local greenhouses will prevent the importation of many foliar diseases,” he says.
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,