Introduction. Bacterial canker,
caused by P. syringae pv. syringae,
is an important disease of stone fruit worldwide. The possibility
of P. syringae pv. syringae infection
through leaf scars and lenticels was evaluated in cherry, peach
and prune. Materials and methods. Laboratory and field
inoculations were performed using cherry, peach and prune stems
to evaluate leaf scar age, chilling and freezing-thawing on bacterial
infection through leaf scars and lenticels. Results and discussion. Increasing
leaf scar age was associated with significant decreases in disease
incidence and length of lesions resulting from leaf scar inoculation
with Pseudomonas syringae pv. syringae in
cherry, peach and prune. A significant reduction in incidence and
lesion length was observed after 4 h of air exposure, and both measures
of infection were reduced to essentially 0 by 2 days of exposure. Prolonged
chilling temperature (2.2 °C) prior to leaf removal had no clear
effect on disease incidence of leaf scar infection, but significantly
decreased lesion length due to leaf scar infection. Cherry was more susceptible
to P. syringae pv. syringae infection
through leaf scars than peach and ‘French’ prune. The leaf scar inoculation
results were consistent with the previous studies. The disease incidence
of lenticel infection caused by bacterial inoculation in ‘French’
prune was very low, but significantly higher than the water control.
Freezing-thawing significantly increased both the disease incidence and
the lesion size via lenticel infection. The lenticel inoculation
data suggest that P. syringae pv. syringae infection through
lenticels is possible under field conditions.