Resistance to Foliar Blight and Crown Rot of Pepper Caused by Phytophthora capsici. T. H. Barksdale, Vegetable Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, MD 20705. G. C. Papavizas, Soilborne Disease Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, MD 20705, and S. A. Johnston, Associate Extension Specialist in Plant Pathology, Cook College, New Jersey Agricultural Experiment Station, Rutgers Research and Development Center, Bridgeton 08302. Plant Dis. 68:506-509. Accepted for publication 19 December 1983. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1984. DOI: 10.1094/PD-68-506.

Resistance to foliar blight of pepper (Capsicum annuum) caused by Phytophthora capsici was found in several plant introduction (PI) lines by using a spore suspension as inoculum in a greenhouse test. PI 201232 and 201234 had the highest level of resistance. These lines had previously been reported resistant to the crown and root rot phase of the disease. For a study of inheritance of resistance, two resistant cultivars, Fyuco and P51, were crossed with the susceptible California Wonder and with each other. In the F₁, F₂, and backcross populations, resistance appeared under the control of a single dominant gene with modifiers and was the same from both sources; however, the F₃ progeny did not fit a single gene hypothesis. Lines selected for resistance to foliar blight in the greenhouse were usually resistant to crown and root rot in the field. Prolonged incubation periods or very high inoculum concentrations of P. capsici could occasionally overcome resistance and result in symptoms on some resistant plants.