Managing Phytophthora Crown and Root Rot in Bell Pepper Using Fungicides and Host Resistance

A resistant pepper cultivar and nine fungicides were tested in both the field and greenhouse and their ability to limit Phytophthora crown and root rot was demonstrated. In both settings, the resistant pepper 'Paladin' and the susceptible pepper 'Red Knight' were inoculated with prepared millet seed infested with Phytophthora capsici. Foliar sprays were applied to the pepper plants on a 7-day interval in the field, and foliar sprays or drenches were applied at 7- or 14-day intervals in the greenhouse. Cv. Paladin had significantly less plant death than Red Knight. In the field, plants treated with fluopicolide or mandipropamid had significantly less plant death than the untreated control plants and, in the greenhouse, all fixed effects, including cultivar, fungicide treatment, application method, and application interval, were significant. The interactions among fungicide-cultivar, application method-cultivar, application method-fungicide, and fungicide-cultivar-application method were also significant in the greenhouse. Treatments applied as drenches provided greater control of P capsici than those applied foliarly. Combining a resistant cultivar with a fungicide applied as a drench may help reduce the incidence of crown and root rot in pepper.