SUSCEPTIBILITY OF SELECTED EUROPEAN PEAR CULTIVARS TO INFECTION BY STEMPHYLIUM-VESICARIUM AND INFLUENCE OF LEAF AND FRUIT AGE

Nonwounded fruit of 16 European pear cultivars (Pyrus communis) and po tted Conference pear plants were inoculated with conidia of Stemphyliu m vesicarium. Cultivars Passe Crassane, Alexandrine, Conference, Doyen ne du Comice, Duc de Bordeaux, Abate Fetel, and General Leclerc were h ighly 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 leaves.