Abstract
A description is provided for Pseudomonas mors-prunorum. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On Prunus spp. especially plum and cherry. DISEASE: Bacterial canker, leaf spot and shoot wilt of stone wits. A definite seasonal cycle occurs in which a winter canker alternates with a summer leaf spot (Crosse, 1954). The symptoms are indistinguishable from those caused by P. syringae on stone fruits. GEOGRAPHICAL DISTRIBUTION: Mainly in Europe, where it has been reported from Denmark, Finland, France, Germany, Great Britain, Greece, Ireland, Netherlands, Switzerland, Rumania, U.S.S.R. (Ukraine), Yugoslavia and, recently, (46, 381) from Italy. Also in Australia (N.S.W.) and Canada (N.S.). (CMI Map 132, Ed. 2, 1966). TRANSMISSION: The pathogen is probably introduced into new orchards most frequently on plant material, where infected spurs may show such slight symptoms as to pass unnoticed (Crosse, 1954). The pathogen is spread locally by wind and rain. In early summer young leaves can be invaded but stems become difficult or impossible to infect at this time. As the leaves mature they lose their susceptibility and large numbers of bacteria are found on their surfaces. These bacteria are carried by rain to infect the branches, which are again susceptible in the autumn, through wounds and incompletely healed leaf scars. This autumn infection leads to the canker phase that develops slowly through the winter and in the spring causes infection of the new leaves as they expand. In summer the bacteria in the cankers die out. The cankers are not, therefore, perennial, but are readily reinfected in the autumn.
Effect of calcium and nitrogen fertilization on bacterial canker susceptibility in stone fruits