Academic Year: 2010-2011
Faculty Mentor: Bonnie H. Ownley
Department: Entomology & Plant Pathology
UTIA Appointment: AG Research/CASNR
Student Department: Forestry, Wildlife,  & Fisheries
Title of Student Project: Disease resistance in heirloom tomatoes
Publications: Gwinn, KD, BH Ownley, and S Nelson. 2011. The Quest for Disease Resistance of Heirloom Tomatoes. Proceedings:   
                       Organic Crops Field Tour. East Tennessee Research and Education Center, Organic Crops Unit. UT AgResearch,
                        Knoxville, TN. 11 p.
Presentations: Student presented at EURECA, “Identifying disease resistance in heirloom tomatoes.” (2011)
Other Products: None
Abstract of Student Project (when Completed):
Cultivated tomatoes (Solanum lycopersicum) are a major cash crop in Tennessee bringing $44.5 million dollars to Tennessee farmers in 2009. With 4,700 acres of tomatoes planted in 2009, Tennessee was the fifth largest producer in the U.S. Heirloom tomatoes are increasing in popularity and demand due to their superior flavor and varieties offered. However, they have a history of being undesirable for commercial growers due to relatively low production, the tendency to crack, and problems with disease. The most common disease of tomatoes in Tennessee is early blight (EB) caused by Alternaria solani. EB can cause severe defoliation, sometimes as high as 100%, and can reduce fruit yield by 70%. Relatively few studies have evaluated disease resistance of heirloom tomatoes, and published results for disease resistance are mixed. Due to the sheer numbers of heirloom tomatoes available, it is reasonable to assume that some will have good disease resistance. Identification of heirloom germplasms with disease resistance would benefit growers and tomato breeders. In this study, 20 varieties, including hybrid and heirloom tomato germplasms, were evaluated for resistance to EB with a whole plant/ leaflet assay. One 10-microliter droplet of Alternaria solani spores (8 ×104 spores per ml) was inoculated onto one leaflet per plant. The entire leaf was enclosed in a plastic bag to maintain high relative humidity. After 10 days, lesion size was measured with a Dino-Lite digital microscope. At 10 and 14 days after inoculation, disease severity of the entire leaf was recorded on a 0 to 5 scale where 0 = no visible lesions, and 5 = more than 75% leaf area affected or leaf abscised. The heirloom varieties, ‘Black Plum’ and ‘Black Prince’, had significantly less severe EB disease at 10 and 14 days post inoculation.
Nelson.jpgStudent:Stephen Nelson


Mentor: Dr. Bonnie Ownley