Bacterial canker of stone fruit
Bacterial canker of stone fruit is a disease caused by Pseudomonas syringae pv. syringae, characterized by sunken lesions on branches and twigs, gum exudation, and dieback of affected areas. It primarily affects stone fruit trees such as cherries, plums, and peaches.
About this problem
Bacterial canker of stone fruit is caused by the bacterium Pseudomonas syringae pv. syringae. This pathogen attacks stone fruit trees, leading to significant damage if not managed properly. The disease is most noticeable in spring when cankers develop on branches and twigs, often accompanied by a gummy exudate. Over time, these cankers can girdle branches, leading to dieback and potentially affecting the overall health of the tree. The disease is often confused with other canker diseases, but its bacterial origin distinguishes it from fungal cankers. The pathogen is spread by rain, wind, and contaminated tools, and it can overwinter in infected plant material.
Symptoms
- Sunken cankers on branches
- Gum exudation from lesions
- Dieback of twigs and branches
- Leaf drop
- Wilting of affected branches
Cause
Bacterial canker is caused by Pseudomonas syringae pv. syringae. The bacterium thrives in cool, wet conditions and can enter the plant through wounds or natural openings.
Conditions that favour it
- Cool, wet weather
- Poorly drained soil
- Wounds or damage to the plant
- High humidity
- Overcrowded plantings
Lifecycle and spread
The bacterium spreads through rain splash, wind, and contaminated tools. It overwinters in infected plant material and becomes active in cool, wet conditions. Breaking the cycle involves removing and destroying infected material and maintaining good sanitation practices.
Plants most affected
- Cherry
- Plum
- Peach
- Apricot
- Nectarine
- Almond
- Prune
- Sweet cherry
- Sour cherry
- Japanese plum
Treatment
Educational information only, and not a substitute for professional diagnosis. Identify the problem before treating it, and check that any product is registered for this plant and this use where you live.
Cultural control
- Prune during dry weather to avoid spreading the bacterium
- Ensure proper spacing for good air circulation
- Remove and destroy infected plant material
- Avoid overhead irrigation
- Maintain tree vigor through proper fertilization
Organic options
- Copper-based fungicides
- Bordeaux mixture
- Neem oil
Chemical options
- Copper hydroxide Used to manage bacterial infections
Read and follow the product label. The label is the legally binding instruction. Confirm the product is registered for this plant and for this use in your area before applying it.
Prevention
- Plant resistant varieties if available
- Avoid planting in low-lying areas with poor drainage
- Disinfect pruning tools regularly
- Monitor for early signs of infection
- Implement a regular pruning schedule to remove dead or diseased wood