A method for in vitro production of conidia of Elsinoe veneta and the inoculation of raspberry cultivars

Abstract

SummaryConidia of two isolates of Elsinoe veneta were consistently produced in vitro by a 3‐stage culture system in which sparsely sporulating microcolonies produced on corn meal agar were used to ‘seed’ Czapek‐Dox V8 juice agar. E. veneta then sporulated on this medium if dises were floated mycelium uppermost on sterile distilled water for 24 h at 25°C. Both isolates also produced microconidia in vitro.Only the growing apices of raspberry canes were susceptible to infection. Of 12 genotypes inoculated in the glasshouse, a red raspberry derivative of Rubus coreanus, EMRS 2769/9, was the most resistant and the black raspberry selection SCRI 815286 and cv. Malling Delight were the most susceptible. Of four red raspberry cultivars inoculated in the field cv. Malling Orion was the most susceptible. Inoculated flowers and developing fruits produced malformed fruits because infected drupelets were smaller or slower to ripen than uninfected ones.