Growers are reminded of the value of monitoring their orchards for evidence of Psa through autumn. Psa inoculum can be mobile within orchards regardless of the time of year but risk always increases as temperatures drop and periods of rain increase.

This image taken last week clearly signals exudate production is being triggered by our current weather patterns, and the recommendation is removal (and effective disposal) of the Psa infected material to help reduce this reservoir of Psa inoculum.

Other tell-tale signs of inoculum build-up include new spotting on Bruno suckers or new growth, especially in new development blocks which are more vulnerable to infection.

It can be more difficult to identify new infections in Gold3 blocks as leaf spotting is less prevalent, but the trap plant data from the recently completed Gold Futures research project clearly demonstrated inoculum presence in autumn for most sites.

A strong copper programme is recommended to protect new development blocks and also harvested blocks, as well as Actigard for blocks where there is no risk of residue to unharvested fruit. Research has shown defence genes in mature Hayward leaves are upregulated following post-harvest applications of Actigard and work is in progress to confirm effects on Gold3. Read the latest Actigard post-harvest technote here.