REACTION OF PLUM CULTIVARS AND ROOTSTOCKS TO BACTERIAL BLIGHT (PSEUDOMONAS SP.)

The bacterial blight caused by the Gram-negative bacteria Pseudomonas sp. is a significant problem in stone fruit orchards. The resistance or tolerance of the cultivars is one important strategy for disease control. In the frame of a study conducted with the support of the BNSF, administrative contract Kn-06 M 46/2, was compared the reaction of plum cultivars and rootstocks, after inoculation with the bacterial pathogen Pseudomonas sp. Flowers and shoots of the cultivars 'Topgigant Plus' and 'Jojo' grafted on the two rootstocks -'Docera 6' (Prunus domestica L. & khcy; Prunus cerasifera Ehrh.) and the seedling myrobalan plum rootstock (Prunus cerasifera Ehrh) were artificially inoculated. In addition, two years old rootstocks 'Docera 6', seedling P. cerasifera and 'Myrobalan 29C' (Prunus cerasifera) also were inoculated with bacterial suspension. The cultivar 'Topgigant Plus' had lower susceptibility to flower infection when grafted on the seedling rootstock than 'Docera 6'. The reaction of rootstocks fourteen days after inoculation showed a lesion diameter of 400 mm on 'Docera 6', 433 mm measured on 'Myrobalan 29C', and 41 mm on the seedling rootstock P. cerasifera.