Early protection important to protect flowerbuds
Recent research presentations alerted growers of the need for strong Psa protection programmes, both at budbreak and through the early weeks of canopy development.
For both Hayward and Gold3, flower-buds were seen to become infected as early as 1-2 weeks after budbreak if innoculum is present. Infection risk ramps up with rainfall, and strong winds similarly add risk. Flower-bud infections only become visible 2-3 weeks after infection, with browning of flower sepals becoming visible.
We know Psa moves from outside the flower-bud into internal flower parts, so a regime to minimise innoculum early must be in place and should include monitoring to identify Psa hot spots, removal of infected material, and the use of an integrated spray programme using products which match the orchard risk.
Many canopies now have leaf size sufficient for application of the elicitor Actigard, and for sites where challenge of Psa is high, bactericides can be considered.
Ongoing copper rounds are needed to protect the rapidly expanding young canopy tissue.
A list of current protective spray products is available on the KVH website here.