Location: Vegetable ResearchTitle: Grafting susceptible pepper on resistant rootstocks to manage Phytophthora capsici in heavily infested fields
Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 11/20/2018
Publication Date: 12/4/2018
Citation: Kousik, C.S., Ikerd, J.L., and Hassell, R. 2018. Grafting susceptible pepper on resistant rootstocks to manage Phytophthora capsici in heavily infested fields. Proceedings of the 2nd international Soilborne Oomycete conference, Page 39. https://doi.org/358867.
Technical Abstract: Pepper (bell and hot) is a major vegetable crop grown in most states in the USA on 64,450 acres and valued at $785 million in 2017 (USDA NAAS Vegetable Summary). Phytophthora capsici which causes crown and root rot of peppers is prevalent in most pepper producing regions of the USA. The primary means of managing P. capsici is through application of fungicides, and many effective fungicides are currently available to the growers. Several moderately resistant pepper cultivars are also available for use by growers. Numerous germplasm sources with resistance have been identified and utilized in various breeding programs. At the U.S. Vegetable Laboratory, USDA, ARS in Charleston, South Carolina, we have been developing rootstocks for grafting bell peppers for managing crown and root rot. Two resistant lines were developed from PI 201232 obtained from the U.S. National Plant Germplasm system (https://npgsweb.ars-grin.gov). After screening and selections for three generations in a greenhouse, two lines with high levels of resistance to crown and root rot were developed. The two lines were different with respect to fruit shape and size and were also highly resistant to a South Carolina isolate of P. capsici in inoculated greenhouse and field evaluations compared to commercial cultivars Jupiter, Paladin, and Charleston Belle. The pepper cultivar Jupiter which is highly susceptible to P. capsici was used as the scion and grafted onto the two resistant lines. Jupiter grafted onto itself was used as the susceptible control in two trials conducted in a heavily infested field in summer and fall of 2018. In both the trials the areas under disease progress curves for Jupiter grafted on the two lines was significantly lower compared to Jupiter grafted onto itself. Most plants (90%) of self-grafted Jupiter succumbed to crown and root rot by end of the two seasons. Grafting on resistant rootstocks will be an added strategy for managing P. capsici especially in organic production where not many fungicides are available for management of the disease. To prevent breakdown of resistance in heavily infested fields, an integrated disease management strategy using the combination fungicides, resistant rootstocks and proper drainage would be advisable.