Written by  Orchard Plant Protectuin Guide

Summer trunk canker

Summer trunk canker is more common during prolonged wet, windy spring and summer seasons on soils that are poorly drained.

Optimum soil temperatures for infection occur from October to March.
Overwatering favours the disease.
Staking young trees to reduce trunk movement and infection at ground level is recommended.
Non-pesticide management
Avoid over-irrigation, especially during spring and autumn as this is when soil temperatures are most suitable for disease development.
The disease can spread in contaminated water, therefore orchardists should be careful to use clean water where possible for irrigation.

See this article in Tree Fruit Nov 2019