Susceptibility of Selected European Pear Cultivars to Infection byStemphylium vesicariumand Influence of Leaf and Fruit Age

Nonwounded fruit of 16 European pear cultivars (Pyrus communis) and potted Conference pear plant were inoculated with conidia of Stemphylium vesicarium. Cultivars Passe Crassane, Alexandrine, Conference, Doyenne du Comice, Duc de Bordeaux, Abate Fetel, and General Leclerc were highly susceptible. Cultivars Williams, Blanquilla, Beurre Hardy, Louis Bonne, Grand Champion, and Highland were slightly or not susceptible. The susceptibility of fruit decreased logarithmically from fruit set to harvest in very susceptible cultivars. Younger leaves developed 1.8-3 times more disease than older leave