Detection of Phytophthora capsici in Pepper and Cucurbit Crops in Ohio with Two Commercial Immunoassay Kits. S. A. MILLER, Department of Plant Pathology, Ohio State University, Ohio Agricultural Research and Development Center, Wooster 44691. R. G. BH AT, and A. F. SCHMITTHENNER, Department of Plant Pathology, Ohio State University, Ohio Agricultural Research and Development Center, Wooster 44691. Plant Dis. 78:1042-1046. Accepted for publication 20 July 1994. Copyright 1994 The American Phytopathological Society. DOI: 10.1094/PD-78-1042.

Phytophthora capsici was shown to be the principal species associated with Phytophthora blight of peppers and cucurbits in Ohio during 1992 and 1993. Both A1 (31.5%) and A2 (64.2%) compatibility types were found in peppers, and only A2 isolates were obtained from cucurbits. Phytophthora cactorum was recovered from two cucurbit samples. The Alert Phytophthora "flow-through" immunoassay and the Agri-Screen multiwell ELISA kit E for Phytophthora were compared for their efficacy. The former detected P. capsici in pepper and cucurbit crops, and had the advantage of being rapid (10 min) and easy to perform. The latter was effective in detecting P. capsici in pepper tissue, but absorbance values for healthy cucurbit tissues were relatively high. Agreement between ELISA and isolation of P. capsici or P. cactorum on semiselective medium was excellent for both kits. Phytophthora antigen was detected in three of seven field soils using the ELISA kit E combined with a soil organic matter extraction concentration protocol.

Keyword(s): enzymc-linkcd immunosorbent assay