|DISEASED CANADA RED CHERRY|
|BLACK KNOT OF PLUM|
The reversion to winter has made us all want to go somewhere warm and sunny, so we are considering a Caribbean cruise, but really can't afford it. Perhaps we could all be employed on a cruise liner; buddy as security, and Joan and I most likely as ballast.
Black knot of plum is a serious fungal disease of most species and varieties of plums and cherries, including some that are used as street trees, such as the Canada Red Cherry shown here, located at Ten N. Third Street.
An infected tree or shrub develops large, pulpy tissue on new twigs, which eventually develops into hard black "knots" which girdle branches and kill or seriously compromise the plant. Early detection and removal of the fungal growth by pruning is necessary for control, as well as spraying with the proper fungicide. When pruning infected growth it is essential to prune well below the knot, and then sterilize the pruning tool in bleach or alcohol before making another cut. The fungus is technically named Apiospourus morubus.
The above tree is so badly infected it must be taken down, and it will be buried or burned to prevent the spread of the disease, which spreads by arial borne spores. We no longer plant Canada Red Cherry because of its susceptibility to the disease.