Canker

Canker is a plant disease characterized by localized dead or dying areas on stems, branches, and trunks. It can be caused by a variety of pathogens, including fungi and bacteria, and often occurs when plants are under stress. Cankers can weaken or kill branches and even entire trees if they girdle the stem.

Causes and Symptoms:

• Pathogens: Fungi and bacteria are the most common causes of cankers.
• Stress: Plants under stress from factors like drought, cold, or insect damage are more susceptible to cankers.
• Wounds: Injuries, such as from pruning or weather events, can provide entry points for pathogens.

Symptoms

Cankers can appear as sunken, swollen, cracked, or discolored areas on the bark. They may be small initially but can grow over time.

Girdling

If a canker completely encircles a stem or branch, it can kill the tissue above it.

Common Types of Cankers:

• Nectria Canker: Characterized by sunken areas on twigs, branches, and trunks, often starting at leaf scars or wounds.
• Bacterial Canker: Common on cherries and plums, with symptoms including sunken areas, swollen stems, and shothole leaves.
• Citrus Canker: A bacterial disease that causes raised brown lesions on citrus fruit, leaves, and stems.
• Diplodia Canker: More common on stressed pines, often causing sunken areas and dieback.
• Stem Canker: Can affect various plants, including tomatoes and soybeans, causing lesions and potentially killing the plant.

Control and Prevention:

• Pruning: Remove cankered branches and stems, cutting back to healthy wood and sanitizing pruning tools.
• Plant Health: Maintain healthy plants by providing adequate water, fertilization, and pest control.
• Disease Resistance: Choose resistant varieties when planting new trees and shrubs.
• Fungicides/Bactericides: In some cases, fungicides or bactericides can be used to control cankers.
• Prompt Treatment of Wounds: Treat any injuries on trees promptly to prevent pathogen entry.