Autumn brings reports of Psa-V

With autumn weather firmly settled in, reports of Psa-V symptoms are on the rise in some orchards. Mostly from sites where the disease has been challenging in the past.

Autumn observations:

• Young Gold3 scions girdled in early March were showing exudate at the girdle points. Infection in the trunks and leaders were also common in these plants.
• Exudate from trunk lenticels on young scions.
• A Gold3 block, which recovered strongly after ongoing spring cut-out of Psa-V, showed indications of infection beginning to move back through some plants. Symptoms included dieback from leader cut points, dehydrated strung laterals and blackened canes.
• New spotting was seen on Bruno suckers and/or young plants, particularly where a comprehensive spray programme had not been maintained.
• On some Gold3 blocks, cane die-back and fruit shrivel was seen during harvest.

Recommendations:

• Monitor orchard areas where Psa-V infection has been present in the past and remove infected material as soon as possible. Removal and disposal of infected material outside the production area remains a key tool in Psa-V management and a key component of the industry management strategy to minimise the build-up and spread of any resistant Psa strains that may have developed.
• Maintain excellent tool hygiene and protect pruning cuts to avoid infection transfer.
• Trim high male growth, particularly in sites prone to frost. Warm temperatures have led to growth flushes, creating tissue that will be vulnerable to frost damage and Psa-V infection when temperatures turn colder.

Click here for images of Psa symptoms in girdled Gold3
Click here for images of Psa symptoms in young Gold3 canopy
Click here for images of Psa symptoms in young blocks