Effect of Vine Cutback On Symptom Severity and Virus Titers of a Resistant and Susceptible Sweetpotato Variety

The most important virus disease in sweetpotato is Sweet potato virus disease (SPVD), a result of co-infection of Sweet potato chlorotic stunt virus (SPCSV) and Sweet potato feathery mottle virus (SPFMV). Characteristic symptoms include chlorosis, small, deformed leaves, and severe stunting. Yield reductions of up to 90% have been reported in SPVD affected plants. Our objective was to compare symptom development and the pattern of accumulation of the two viruses in mixed infections in an SPVD resistant (NASPOT 1) and susceptible (Beauregard) variety in plants cut back and allowed to regrow from axillary buds. Typical symptoms developed on graft-inoculated Beauregard after nearly one month of growth in the greenhouse while symptom development on NASPOT 1 was minimal at this time. Half the plants of each variety were then cut back and all plants were allowed to reproliferate for an additional month. Virus symptoms developed on both varieties of plants that were cut back but not on NASPOT 1 plants that were not cut back. Leaves were collected from all plants for analyses of virus titers using real-time PCR.