Studies on the epiphytic persistence of Xanthomonas campestris pv. pruni
Twig cankers have been often cited as the probable overwintering sites for Xanthomonas campestris pv. pruni (EPPO A2 quarantine pest). The aim of this study was to determine whether Xanthomonas campestris pv. pruni could also persist as epiphytic populations. Leaves, twigs, buds, flowers and fruits of susceptible peach (15 year-old Prunus persica cv. Blake) and plum (13 year-old Prunus domestica cv. Methley) have been sampled at intervals during a 13 months period (1984-1985), in South Carolina (US). During the growing season, samples were collected at 5 to 15 days intervals and after leaf fall in autumn, the sampling period was reduced to once or twice each month. The bacterium has been found on all symptomless organs each time they were sampled. Epiphytic populations were consistently found, though their levels were variable according to the time of the year and the organ on which they were isolated. The authors concluded that these results show that Xanthomonas campestris pv. pruni can be found on symptomless plant surfaces and can survive on stems and buds throughout the whole year. This may have consequences on control strategies against this disease, such as timing of chemical treatments (if allowed) and pruning (removal of diseased twigs during pruning may not be as useful as previously thought for disease prevention).
Shepard, D.P.; Zehr, E.I. (1994) Epiphytic persistence of Xanthomonas campestris pv. pruni and peach and plum.
Plant Disease, 78 (6), 627-629.