OVERWINTERING OF CONIDIA OF VENTURIA-INAEQUALIS IN APPLE BUDS IN NEW-YORK ORCHARDS

Viable conidia of Venturia inaequalis were detected in dormant apple buds and on early developing apple tissues during 1988-1990. Zero to 142 viable conidia per bud were detected from the inner tissues of flower buds. Apple scab lesions were observed on the adaxial bud scale surfaces of 12 of 1,000 dormant buds just before budbreak from one orchard, and 77% of the conidia arising from the lesions were viable. Viable conidia were rarely detected on the exterior surfaces of overwintered buds or lesions on infected shoots. They were never detected in lesions on overwintered foliage or fruit that were assayed from March to June. When apple tissues at early stages of bud growth were inoculated with conidia, an increase in sepal and fruit infection resulted.