Redbud trees are one of spring's gifts to the world because of the color and early timing of their blooms. Ornamental in nature, redbuds thrive in all but the coldest and hottest regions of the United States. Caring for redbuds is relatively simple as they are relatively disease-resistant. Redbud bark disease or botryosphaeria canker is the most serious and potentially fatal disease redbuds face.
Redbud trees are ornamental, short-lived trees that are valued for their pink to purple blooms that are among the earliest of spring. Found as understory trees in forests, they do well in shade or full sun. They tend to be smaller trees, reaching 20 feet in height and about the same in width. With a typical life span of 20 years, redbud trees are susceptible to surprisingly few diseases. Verticillium wilt, leaf anthracnose and canker, a disease which affects the wood and bark, are the most common diseases affecting redbuds, according to the University of Wisconsin.
Botryosphaeria canker is a fungal disease. It attacks ornamental trees and shrubs, especially those weakened by environmental circumstances, injuries or tress. Stress caused by drought seems to be a primary factor, notes the University of Kentucky. The fungus kills bark and sapwood by cutting off the nutrient and water supply, leaving the redbud tree unable to sustain itself
Cankers may take on slightly different appearance depending on the age of the tree and the advancement of the disease. New cankers are small, oval lesions that grow into larger areas of damaged tissue. The cankers are dark and rough in appearance. They easily peel away from the tree. A single limb may have numerous cankers that continue to grow until they meet and girdle the limb. If cankers spread to the trunk, it is a matter of time until they girdle the trunk and kill the tree.
The only treatment is to remove the infected branches. All branches showing signs of canker should be cut back 8 inches below the canker. Tools should be sterilized with bleach or alcohol between cuts to prevent further spread of the disease. When possible, make cuts just above the branch collar. Diseased branches should be removed from the site and destroyed.
A healthy tree is the best prevention against canker and other diseases. Trees that are stressed or injured are more likely to contract this disease. Use care when mowing not to nick the trunk with the mower. Do not plant trees outside their recommended zone as redbuds in climates they are not suited to will stress them. The most critical and common stressor of trees is drought. During dry periods, water redbud trees regularly.