High Psa risk weather predicted

30 September 2021

The Psa Risk Model currently predicts moderate or high Psa risk weather for all regions from Monday 4 October to Saturday 9 October, ahead of expected ongoing rain fronts.

This increases the risk of Psa inoculum build up and potential spread within orchards as rain is a known driver of Psa infection in any season.

Growers are urged to ensure Psa protectant sprays are in place ahead of this wet period, as both Gold and Hayward vines will have young vulnerable leaf and flower bud tissue now emerging. Recent research has shown that early protection is key with the next two-to-three-week period critical to protect against leaf spotting and flower bud infection. Infection generally takes two weeks to show, with early October infection periods leading to the rash of leaf spotting and sepal browning commonly seen around Labour weekend.

Hayward growers with historical Psa challenges should also be planning pre-flower girdles, one month prior to flowering.

For Red growers, flowering is fast approaching and copper, Aureo Gold and Actigard should be considered to provide ongoing protection. Growers considering applying bactericides to Gold or Hayward blocks adjacent to Red19 blocks must avoid any risk of spray drift to the Red19 crops.

The Paengaroa weather station risk forecast below is typical of the current risk predicted, with red bars predicting high-risk and yellow bars predicting moderate forecast risk.