Crown rot (Phytophthora cactorum) in glasshouse‐grown strawberries at East Mailing Research Station

Abstract

SUMMARYFrom 1973 to 1977 the spread of crown rot (Phytophthora cactorum(Leb. & Cohn) Schroet.) in glasshouse‐grown strawberries at East Malling Research Station (EMRS) threatened to disrupt the production of virus‐tested stocks. An eradication programme involving trickle irrigation of plants, rooting ranners above the level of mother plants, regular inspection for disease and routine tests for latent infection, special precautions at repotting and annual renewal of mother plants eliminated the disease in two years, except in a quarantine house containing new importations.Isolates of P. cactorum from strawberry plants and apple trees were moderately or highly virulent to their original hosts but caused only latent infection or limited necrosis in reciprocal inoculations. This supports the separation of the strains commonly attacking these hosts as distinct pathotypes. The evidence suggests that crown rot entered the strawberry stocks at EMRS with infected introduced plants and not from local field sources.