Fungicide application and residues in control of Blumeriella jaapii (Rehm) Arx in sweet cherry

Abstract

To minimize harmful effects of the fungicide application in sweet cherry orchards, it is necessary to use them in accordance with the good agricultural practice and to monitor presence of their residues. Cherry leaf spot caused by Blumeriella jaapii is a significant sweet cherry disease which control is heavily dependent on fungicide treatments. In this study, effects of fungicide treatments against B. jaapii and fungicide residues remaining in sweet cherry fruits after the treatments were evaluated, and the causal agent of cherry leaf spot was confirmed on cherry leaves from untreated control plots using conventional phytopathological techniques (isolation on nutrient media and morphological traits of developed fungal colonies). The trial was set up at two localities in south Serbia (District of Niš), in sweet cherry orchards, according to EPPO methods. Fungicides tested against B. jaapii were based on dodine (650 g a.i./kg) WP formulation, at concentration of 0.1% and mancozeb (800 g a.i./kg) WP formulation, at concentration of 0.25%. During the trial, two evaluations were carried out. Fungicide efficacy was determined according to Abbott. The obtained data were statistically processed by ANOVA and LSD test. In both sweet cherry orchards high efficacy in control B. jaapii was registered in case of dodine application efficacy of 96.3-98.9%, while mancozeb showed slightly lower efficacy of 91.0-95.6%. The results of the dissipation dynamic suggest that the dodine dissipation curves followed the first-order kinetic (Ct=6.23e−0.09, with R2=0.986) and its half-life in sweet cherry fruits was 7.7 days. The final residues in sweet cherry fruits were below the MRL (3 mg/kg) 21 days after the application. The results indicate that sweet cherry fruits can be safely consumed after dodine based fungicides applications at the recommended rate.