Homeowners like to landscape with the river birch tree because of its unique and attractive paper-like bark. But more often than not, the river birch is grown in conditions that are too dry. And while the river birch may survive, this famously disease resistant tree becomes more susceptible when under the constant stress of unsuitable growing conditions.
Birch canker is an increasingly common river birch disease. Infected trees develop cankers or swollen areas near improperly made pruning cuts or broken areas of branches. As the cankers grow, they eventually cut off the water supply to the affected branch. The best remedy for birch canker is to prune the affected branch.
Heart Rot Tree Disease
The fungus that causes heart rot finds its way into the heart of the tree through a wound or section of barkless wood. The first symptom of heart rot tree disease is often a conk somewhere on the exterior of the tree. The general rule is that for each conk present on the tree, a cubic foot of heart wood has been eaten away by the fungus. In healthy trees, heart rot will only feed on one localized area and not on healthy wood. Prevent the spread of heart rot by minimizing pruning wounds. If you suspect that your river birch suffers from heart rot, have it inspected by a professional. It may be a falling hazard.
Generally, anthracnose does not pose a significant threat to river birch trees. Anthracnose often attacks after cool and wet weather during bud break. Affected leaves will develop small, irregularly shaped brown circles with darker brown margins. Particularly virulent infections may also cause premature bud and leaf drop, or girdle small twigs, cutting of their nutrient supply and killing them. Anthracnose can be treated by pruning the affected tissue. Trees that suffer from repeated attacks, which can severely weaken a river birch, should be sprayed with a preventative fungicide spray prescribed for birch anthracnose in early spring as soon as the buds break.
Wetwood or Slime Flux
Slime flux is caused by soil born bacteria. Infected river birches will ooze a slimy, smelly brown liquid from cracks or wounds in the wood of their roots, branches or trunks. There is no cure for bacterial wetwood. However, the bacteria responsible for the disease raises the pH on the interior of the tree as it feeds, which prevents the wood from decaying.