A plant canker is a small area of dead tissue, which grows slowly, often over years. Some cankers are of only minor consequence, but others are ultimately lethal and therefore can have major economic implications for agriculture and horticulture. Their causes include a wide range of organisms as fungi, bacteria, mycoplasmas and viruses. The majority of canker-causing organisms are bound to a unique host species or genus, but a few will attack other plants. Weather (via frost or windstorm damage) and animal damage can also cause stress to the plant resulting in cankers. Other causes of cankers is pruning when the bark is wet or using un-sterilized tools.[1]
Although fungicides or bactericides can treat some cankers, often the only available treatment is to destroy the infected plant to contain the disease.
Tree cankers (right) are caused by injuries to the bark that allow pathogens or insects in to infect the tree. Compared above is a healthy tree and segment (left) to a tree infected and containing a canker.
Ash bacterial canker, now understood to be caused by the bacterium Pseudomonas savastanoi, rather than Pseudomonas syringae. After DNA-relatedness studies Pseudomonas savastanoi has been instated as a new species.[3]
