First Report of Phytophthora capsici on Cucumber and Melon in Southeastern Spain.

Abstract

In autumn 1999, crown and root rot along with wilting of cucumber (Cucumis sativus L.) were observed in greenhouses in southeastern Spain (Granada). Symptoms appeared again during the 2000 to 2001 growing season. In spring 2001, root and crown symptoms were observed also on melon (Cucumis melo L.) in greenhouses in another area of southeastern Spain (Almeria). Isolates from diseased plants from both locations were identified as Phytophthora capsici (Leonian). Isolates produced papillate sporangia of variable shape, some of them with two or three papilla. Sporangia were caducous with pedicels of variable lengths that could be longer than the sporangia. Three isolates were crossed with P. capsici strains of known mating type. All isolates produced amphigynous antheridia and were mating type A1. Isolates grew well at 35°C and did not produce chlamydospores. Pathogenicity was examined for one isolate from cucumber and one from melon. Cucumber and melon plants at the four-leaf stage and pumpkin (Cucurbita maxima × C. moschata) plants at the five-leaf stage were inoculated with a mycelium suspension. Both isolates caused wilting and death of plants on the three host species tested. The pathogen was reisolated from roots and stems of diseased plants. To our knowledge, this is the first time P. capsici has been found on cucumber in Spain. It is also the first time P. capsici has been found on melon in the greenhouses of southeastern Spain, and the first time it has been reported to cause root and crown rot of melon. Previously, P. capsici has been reported to cause disease of field-grown melon (2) and greenhouse-grown pepper (Capsicum annum) (1) in eastern and southeastern Spain, respectively.