Differential interactions of Phytophthora capsici isolates with pepper genotypes at various plant growth stages

Pepper cultivars from diverse geographic origins were evaluated for resistance to different isolates of Phytophthora capsici under controlled environmental conditions. All accessions tested were susceptible at the four-leaf stage to the six isolates of P. capsici. Inoculation at the eight-leaf stage resulted in significantly different interactions among the accessions and P. capsici isolates. The Korean and U.S. cultivars tested were highly susceptible to the isolates of P. capsici at this stage. In contrast, PI 201234 and PI 201238 had a differential interaction with some P. capsici isolates. At the twelve-leaf stage, Phytophthora blight developed slowly in the Korean and U.S. cultivars that were highly susceptible at the eight-leaf stage. Furthermore, the accessions from the Asian Vegetable Research and Development Center (AVRDC) became highly resistant to P. capsici at this stage.