Tree Canker – Definition & Detailed Explanation – Tree Diseases and Pests Glossary

What is Tree Canker?

Tree canker is a common plant disease that affects the bark, branches, and sometimes the trunk of trees. It is characterized by the formation of sunken, discolored areas on the tree’s surface, which can eventually lead to the death of the affected tree if left untreated. Cankers are caused by various types of fungi, bacteria, or environmental stressors that weaken the tree’s natural defenses, making it more susceptible to infection.

What Causes Tree Canker?

Tree cankers can be caused by a variety of factors, including fungal or bacterial pathogens, physical injuries, and environmental stressors. Fungi such as Nectria, Botryosphaeria, and Phomopsis are common culprits of tree canker, infecting trees through wounds or natural openings in the bark. Bacteria like Pseudomonas and Xanthomonas can also cause cankers, typically entering the tree through wounds or insect damage.

Physical injuries, such as pruning cuts, mechanical damage, or frost cracks, can create entry points for pathogens to infect the tree and form cankers. Environmental stressors like drought, nutrient deficiencies, and extreme temperatures can weaken the tree’s defenses, making it more vulnerable to infection. Additionally, trees that are already weakened by other diseases or pests are more likely to develop cankers.

How to Identify Tree Canker?

Tree cankers are typically identified by the presence of sunken, discolored areas on the tree’s bark or branches. These cankers may appear as dark, cracked, or oozing lesions that disrupt the tree’s natural growth patterns. In some cases, the bark may slough off, revealing the underlying infected tissue. Other signs of tree canker include wilting leaves, dieback of branches, and reduced growth or fruit production.

To accurately identify tree canker, it is important to inspect the tree closely for any signs of infection. Look for sunken areas, discoloration, or oozing sap on the bark or branches. Pay attention to any changes in the tree’s growth patterns, such as wilting leaves or dieback of branches. If you suspect that your tree may have a canker, it is recommended to consult a professional arborist for a proper diagnosis.

How to Prevent Tree Canker?

Preventing tree canker involves maintaining the overall health and vigor of the tree to help it resist infection. Here are some tips to prevent tree canker:

1. Prune trees properly: Avoid making unnecessary cuts or pruning during periods of high disease activity. Make clean cuts at the proper angle to promote healing and reduce the risk of infection.

2. Avoid mechanical damage: Be careful when mowing, trimming, or performing other activities near trees to prevent accidental injuries that can create entry points for pathogens.

3. Provide proper care: Water trees regularly, especially during dry periods, and fertilize as needed to promote healthy growth and vigor. Mulch around the base of the tree to retain moisture and reduce stress.

4. Monitor for pests and diseases: Keep an eye out for signs of pests or diseases that may weaken the tree’s defenses and make it more susceptible to canker. Treat any issues promptly to prevent further damage.

5. Practice good sanitation: Remove and dispose of infected plant material to prevent the spread of pathogens to healthy trees. Clean tools and equipment between uses to avoid transmitting diseases.

How to Treat Tree Canker?

Treating tree canker involves a combination of cultural, chemical, and biological methods to manage the disease and promote healing. Here are some common treatments for tree canker:

1. Pruning: Remove infected branches or cankers to prevent the spread of the disease to healthy tissue. Make clean cuts at the proper angle and dispose of infected material properly.

2. Fungicides: Apply fungicides to protect healthy tissue from infection and reduce the spread of pathogens. Follow label instructions carefully and reapply as needed to control the disease.

3. Biological controls: Introduce beneficial microorganisms or predators to help suppress the growth of pathogens and promote a healthy balance in the tree’s ecosystem.

4. Improve tree health: Provide proper care, such as watering, fertilizing, and mulching, to help the tree recover from the infection and strengthen its natural defenses.

5. Monitor and follow up: Regularly inspect the tree for signs of new infections or reoccurrences of canker and take appropriate action to manage the disease effectively.

Common Types of Tree Canker

There are several common types of tree canker that affect a variety of tree species. Some of the most prevalent types of tree canker include:

1. Nectria canker: Caused by the fungus Nectria, this canker affects a wide range of tree species and typically appears as sunken, reddish-brown lesions on the bark.

2. Botryosphaeria canker: Caused by the fungus Botryosphaeria, this canker affects fruit trees, ornamental trees, and woody shrubs, causing dark, sunken lesions on the bark.

3. Phomopsis canker: Caused by the fungus Phomopsis, this canker affects conifers and hardwood trees, causing sunken, discolored areas on the branches and trunk.

4. Bacterial canker: Caused by various species of bacteria, bacterial canker affects a wide range of tree species and typically appears as oozing lesions on the bark or branches.

5. Hypoxylon canker: Caused by the fungus Hypoxylon, this canker affects hardwood trees, causing dark, sunken areas on the bark and branches.

By understanding the causes, symptoms, and treatments of tree canker, you can effectively manage the disease and protect your trees from further damage. Remember to practice good tree care practices, monitor for signs of infection, and consult a professional arborist for proper diagnosis and treatment recommendations.