This diseased bark eventually cracks open and exposes the wood underneath. The amount of damage caused depends on the type of canker and the poplar species. A serious type of canker can cause mortality of the host and thus should be removed to prevent further spread of the disease. Other types of cankers are weaker and cause a reduction in growth and reduce the aesthetic value of the tree. These types of cankers still wound the tree, and make it more susceptible to other insects and diseases that may lead to the death of the tree.
All cankers weaken the tree resulting in limbs breaking during high winds.
Canker fungi are spread by spores that generally enter the tree through branch stubs or wounds. The spores are usually dispersed in wind currents or by water droplets during a rain, but can also be transported by insects, animals or pruning tools. Trees that are under stress from drought or insects seem to be infected by cankers much easier than healthy trees. An important measure in control is to maintain high vigor of trees by fertilization and watering. Also, to prevent the spread of the disease during pruning, tools must be sterilized after each cut.