BACTERIAL CANKER, AN IMPORTANT DECLINE DISEASE OD APRICOTS AND OTHER STONE FRUITS IN CALIFORNIA
Bacterial canker, caused by Pseudomonas syringae, continues to cause, serious damage to apricot and other stone fruit trees in California. It is especially destructive to young trees, where braches and sometimes entire trees are killed. Most infection leading to canker formation appears to occur through leaf scars and is caused by bacteria that survive much of the year as epiphytes. Pruning wounds do not appear to be an important infection court, and time of pruning has not been correlated with canker severity. Canker activity is correlated with tree dormancy, and extension of the dormant period as a result of inadequate winter chilling increases disease severity. Canker generally is more serious in trees growing on light sandy soil than in those on heavier soil. Shallow soil, inadequate nutrition, and the nematode Macroposthonia xenoplax also are predisposing disease factors. Canker severity is much less in French prune and several plum cultivars propagated on Lovell peach than on plum rootstocks and there is some evidence that canker in apricot on peach rootstock is less destructive. Autumn, postpruning, and early spring sprays of streptomycin or copper compounds have generally provided unsatisfactory control of canker. Preplant soil fumigation with several nematicidal fumigants and postplant fumigation with dibromochloropropane have enhanced tree growth and provided effective control of bacterial canker in several stone fruit areas.
English, H., Davis, J.R., DeVay, J.E. and Lownsbery, B.F. (1981). BACTERIAL CANKER, AN IMPORTANT DECLINE DISEASE OD APRICOTS AND OTHER STONE FRUITS IN CALIFORNIA. Acta Hortic. 85, 235-242