ASSESSMENT OF SENSITIVITIES TO ANILINOPYRIMIDINE-FUNGICIDES AND STROBILURIN-FUNGICIDES IN POPULATIONS OF THE APPLE SCAB FUNGUS VENTURIA-INAEQUALIS

The sensitivity of Venturia inaequalis populations to the anilinopyrim idine fungicides pyrimethanil and cyprodinil was analysed by microscop ic in vivo analysis of conidiophore formation. The sensitivity to the strobilurin kresoxim-methyl was analysed using an in vitro germination assay and by determination of the diseased leaf area and conidia prod uced in vivo. Baseline sensitivities were determined with V. inaequali s populations from control orchards that had never been treated with f ungicides. Comparison of the baseline sensitivities with sensitivities of populations obtained from orchards that had received 43 anilinopyr imidine treatments over 4 years, or from an orchard with 54 kresoxim-m ethyl treatments over 6 years indicated that no resistance to these fu ngicides has developed at the sites sampled.