Tree and Shrub Disease

Cankers are dead areas on the branches, twigs, or trunk of the tree between the live tissue and the bark. Cankers may be caused by disease, fungus, bacteria or injury to the tree (which allows for fungus to penetrate through the bark directly to infect the tree's tissue causing fungal cankers).Cankers will cause dieback of the trees and can be difficult to control. It is also important to note that the tree infected with fungal canker (or injury which resulted in a canker) is more susceptible to insects and disease activity because the overall health of the tree has declined.

Visually, cankers are deformed portions of the tree or shrub such as dead branches, discolored (usually darker) bark, sunken bark or swollen bark. On pines, the cankers often oozes a clear sap which dries as a sticky whitish resin. Other signs to look for are small spores forming around the canker site.

Trees with cankers that are suffering from environmental stresses such as drought, flood, nutrient deficiencies, extreme fluctuations in temperature and shock are more likely to decline than those that are healthy and not suffering from those external forces.

Disease Development Favored by: Environmental Stresses Fungal disease between the bark and tree tissue Wounds on the tree Rain or splashing of water can spread spores Corrective Measures: Pruning out four inches below the canker site during dry weather (ensure to clean all tools before reusing). Keep trees stress free. Mulch around the base, water during drought, choose a proper location for roots and soil conditions, proper feeding.
	Cytospora Canker Oozing near infected area Elongated (up and down) shape Bark often dies at infected site, though remains on the tree for a year.
	Thyronectria Canker Yellow, wilting foliage with dieback where the canker encircles branch Dead bark is usually orange-brown later turning yellow-orange
	Nectria Canker Target-shaped canker Sunken and discolored bark Callus ridges resulting from trees attempt to heal
	Sphaeropsis Canker Causes Tip Blight in Austrian Pines Oozes resin Sapwood discoloration
	Phomopsis Canker Foliage shrivels and remains attached till fall Small spores form on dead bark Cankers are reddish-brown
	Hypoxylon Canker Foliage wilts and yellows, followed by dieback The bark will shed revealing tan-colored fungus spores
	Botryosphaeria Canker Dieback Sapwood discoloration Leaf spots and blights