Fungicidal suppression of symptomless latent infections of Monilinia fructicola in European plums

Abstract

European plums (Prunus domestica “Stanley”) with a high incidence of symptomless latent infections of Monilinia fructicola, were harvested soft-ripe or firm-ripe, surface disinfested in NaOCl, soaked for 4 min in fungicide suspensions at 20°C and incubated for 7-11 days at >95% RH at 20°C. Using soft-ripe fruits, all 12 fungicides reduced brown rot relative to the water check after 7 days incubation, with tebuconazole and flusilazole being numerically superior. Using firm-ripe fruits, five sterol-inhibiting fungicides and iprodione reduced brown rot infections after 7 days incubation, with tebuconazole, flusilazole and myclobutanil being numerically superior. Fruits were soaked for 4 min in suspensions of tebuconazole and flusilazole at 33, 67, and 100 mg a.i./L, and incubated for 7-8 days. Treatments were moderately effective with no rate response except for soft-ripe plums soaked in flusilazole. Five sterol-inhibiting fungicides were applied twice at mid-season to Stanley trees having fruits with a high...