Evaluating management tools to control Phytophthora capsici in pepper and eggplant

Phytophthora capsici is an important pathogen of pepper and eggplant. Effective management requires a multifaceted approach including both chemical and cultural control methods. Greenhouse, laboratory, and field experiments were conducted to evaluate resistance in pepper and eggplant to P. capsici. Select fungicides were tested to determine their efficacy in controlling Phytophthora crown and root rot in pepper. Results from the greenhouse study, indicated that four Michigan P. capsici isolates differed in virulence on the roots and crowns of 31 pepper lines. The roots and crowns of pepper lines CM334, NY07-8001, NY07-8006, and NY07-8007 were resistant to the four P. capsici isolates. Isolate 12889 was more virulent on pepper fruit than the other two isolates, OP97 and SP98. When fungicides were applied in the field to the resistant cultivar Paladin and the susceptible cultivar Red Knight they effectively controlled crown and root rot on Paladin but adequate levels of control were not achieved on Red Knight. In the greenhouse, drench applications had significantly lower area under the disease progress curve values than foliar applications; treatments applied every 7 days had reduced plant death compared to treatments applied every 14 days. When eggplant lines were screened for resistance to P. capsici, line EG195 was resistant to fourteen isolates. The interaction between zoospore concentration and P. capsici isolate significantly influenced lesion size on eggplant fruit.