Some factors predisposing grape berries to infection byBotrytis cinerea

Abstract

Abstract Botrytis cinerea was frequently isolated from rapidly senescing or moribund tissues (stamens, calyptrae, immature berries and flowers or partly developed berries, miscellaneous leaf, stem and tendril pieces) of grapevine; the calyptrae being more heavily contaminated than the stamens in the flower bunches. There was a significant difference in the extent to which intact and injured berries were infected by the pathogen 3 weeks before harvest. Bunches infested with light-brown apple moth (Epiphas postvittana (Walker)) were more rapidly infected by B. cinerea. Of thecultivars tested, ‘Mataro’ was the least susceptible to predisposition wounding because the berries had a high critical turgor; however, once the berries were split, they appeared to be as susceptible to infection as the other cultivars tested. The longer the berries were exposed to surface wetness, the higher the degree of infection. A minimum temperature difference of 9°C caused a significant difference of 6-12 h in the length of the infection period. Infection of berries occurred over a wide range of temperatures (15-25°C).