Some experiences in control of apple scab in Serbia

Abstract

Apple scab caused by Venturia inaequalis (Cooke) G. Winter is recognized as the most important disease of apples in Serbia. Fungicides remain the primary tool for managing this disease and, due to its polycyclic nature; repeated applications are required over the course of a single season. During 2004-2010 we have conducted many trials for evaluation of chemical control of this disease. The following compounds were tested: pyraclostrobin + dithianon, trifloxystrobin + captan, kresoximmethyl + dithianon, difenoconazole, pirimethanil, boscalid + pyraclostrobin, pyrimethanil + fluquinconazol and fenbuconazole. Trials were set according to EPPO guideline PP 1/5(3). A complete randomized block design with four replicates per treatment was used in the experiments. Mean percent disease control values were calculated from the evaluations made towards the end of the trials, when differentiation between the treatments was the most obvious. Data were analysed by one-way completely randomized ANOVA, and means comparison performed by Duncan's test. The infection of untreated control plots ranged from 23.0% to 77.5%. All treatments were effective against V. ineaqualis and significantly reduced disease severity in all experiments, compared with the untreated control. Comparing the tested fungicides, pyrimethanil applied alone and mixtures of trifloxystrobin + captan, kresoxim-methyl + dithianon, pyrimethanil + fluquinconazol and pyraclostrobin + dithianon demonstrated the highest efficacy in all trials (85.6%-97.2%). DMI fungicides (difenoconazole and fenbuconazole) and mixture of boscalid + pyraclostrobin exhibited lower efficacy (68.5% - 75.1%) compared to other tested materials.