Biological control (Crown rot and 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.