Meristem culture for the elimination of the strawberry crown rot pathogen Phytophthora cactorum

Two methods to induce a symptomless infection of crown rot (Phytophthora cactorum) in stolons of three strawberry (Fragaria×ananassa) cultivars were evaluated. Spraying a 10−4 ml zoospore suspension was the most effective method, producing a mean infection rate of 12%. Meristem cultures were subsequently established from all of the inoculated stolons and tested eight weeks later for the presence of P. cactorum using a PCR-based assay. A total of 784 meristems were excised and DNA was successfully extracted from 505 viable meristem cultures, 46 of which had been excised from stolons that were shown to have a symptomless infection of crown rot. No viable meristems were found to be infected with the pathogen. This investigation confirmed the suitability and reliability of meristem culture for the production of strawberry plants free from crown rot.