The Leaf Scar as an Avenue of Infection for the Cherry Bacterial Canker Organism, Pseudomonas mors-prunorum Wormald

Abstract

THE development of branch cankers from previously infected fruiting spurs was noted by Wormald¹ in his original etiological study of the bacterial canker disease of cherry (Ps. mors-prunorum), and later by Webb², who concluded that most branch cankers originated in this way. Records made over the past two years during field observations on 5–12 year old cherries of several varieties have confirmed this view. Between 90 and 100 per cent of branch cankers examined, depending on the age and variety of the tree, were around the base of a dead spur. This association, together with the frequent occurrence of dead spurs with incipient cankers at the base and dead spurs without basal cankers, clearly indicated the sequence of infection.