Foot rot of prickly pear cactus caused by Phytophthora nicotianae.

A foot rot of prickly pear cactus (Opuntia ficus-indica) was observed in commercial orchards of a major producing area in Sicily [Italy]. Symptoms were exudates oozing from the basal stem, soft rot and discoloration of internal tissues, and eventual wilting of the plant. The disease occurred in clay soils after prolonged periods of rain. Phytophthora nicotianae was consistently isolated from infected tissues. Koch''s postulates were completed with plants of prickly pear cactus grown in containers. This is the first record of P. nicotianae as a pathogen of prickly pear cactus.