The aim of the paper was to determine the effect of autumn infestation of leaves for apple cultivars (McIntosh, Idared, Jonagold) on the occurrence of conidia of Venturia inaequalis on twigs. It was found that high infestation of apple leaves in autumn is advantageous to conidia overwintering on twigs. Loosely spread hyphae and conidial spores were more frequently observed on twigs in an orchard where no chemical control was employed. The largest amount of conidial spores was recorded on twigs of unprotected McIntosh apple trees as a result of high infestation of leaves in later autumn. A considerably lower amount of conidia was recorded on twigs of Jonagold apple trees. In orchards under chemical control the conidia wintering occurs less frequently and only if leaves were highly infested in the autumn.

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