Evaluation of Different Phytosanitary Products Against Cladosporium Preharvest Fruit Rot of Raspberry: A 3-Year Field Study

In the province of Québec (Canada), losses in yield due to Cladosporium preharvest fruit rot in raspberry ( Rubus idaeus L.) production have considerably increased in recent years. Currently, no phytosanitary products are registered in Canada to manage the disease. In vitro bioassays and field assays with the cultivars ‘Anne’ and ‘Killarney’ were conducted in this study to evaluate the efficacy of 10 phytosanitary products to inhibit the mycelial growth of Cladosporium cladosporioides and to repress the development of Cladosporium preharvest fruit rot of raspberry. Luna Tranquility, Cueva Commercial, Serenade Opti, and Double Nickel 55 showed the highest efficacy (100%) to repress the mycelial growth of C. cladosporioides. Switch 62.5 WG, Quadris Top, MilStop, Nova, and Elevate 50 WDG showed efficacy values >50%. For cultivar Anne, Switch 62.5 WG, Luna Tranquility, and Quadris Top significantly ( P < 0.01) reduced disease severity at the green and immature fruit stages, with Switch 62.5 WG and Luna Tranquility remaining effective at fruit maturity. Elevate 50 WDG was only effective at the immature stage. In cultivar Killarney, Luna Tranquility and Quadris Top significantly reduced disease severity at the immature and mature fruit stages, whereas Switch 62.5 WG was effective only at maturity. Phytotoxicity symptoms were observed only on plants treated with Cueva Commercial or MilStop. Luna Tranquility, Switch 62.5 WG, and Elevate 50 WDG, currently registered in Canada for the management of raspberry gray mold ( Botrytis cinerea), could be used to manage preharvest fruit rot of raspberry caused by either B. cinerea or Cladosporium spp.