Crown rot
- Do not plant trees on susceptible rootstocks on wet sites. Ensure that drainage is adequate prior to planting. Selecting the right site initially is important.
- Trees are most at risk from crown rot when they are young and are being lifted from the nursery or planted out as this is when damage can occur.
- Trees should not be lifted or planted in wet conditions as rainfall increases the risk of infection.
- Plant trees carefully. Avoid creating locally poor drainage around newly planted trees.
Collar rot
- Planting high grafted trees (minimum 40-70 cm above soil level), or trees with resistant interstocks, will ensure that susceptible scions are less prone to infection by soil splash.
- In mature orchards, keep tree trunks clean of weeds. Check regularly that rabbit guards are not too tight. Keep soil away from the graft union and avoid mechanical damage to the trunk.
- Remove fallen fruit from the base of the trees and into the alleyway where they can be pulverised. Fallen fruit provide a substrate for regeneration of P. cactorum.
- In addition, encourage rapid leaf decomposition in the autumn by use of post-harvest urea sprays and regular mowing to macerate leaves.
- Fallen leaves are the main substrate for P. syringae multiplication.