We have been seeing lots of canker in landscape plants over the last 5 years. Cankers are caused by wounds being infected with fungi. The wounds can be caused by everything from extreme winter cold to woodpeckers.

There are several fungi that infest the stems of trees and shrubs and the infection causes a canker (infected wound) in oak, arborvitae, cherry laurel, Leyland cypress, and many other trees and shrubs. These fungi infect wounded branches on plants eventually killing the branch. Wounds can be caused by pruning, storm damage, cold damage, or excessive wetness.

There is no real treatment for canker stem diseases. Best management practices are:

• Try to prevent damage to trees. Stressed and wounded plants are more likely to be infested.
• Prune to allow air flow in plants so that they will dry out after rain.
• Clean out fallen leaves from the insides of shrubs.
• Do not bury plants too deep in mulch.
• Locate cankers and prune out infected branches below the wound.
• Fertilize and irrigate affected trees regularly to promote healing and good health.