Bad weather in Italy leads to increase in Psa symptoms

20 April 2017

In the last Bulletin we talked about the need to increase Psa protective sprays in line with the seasonal weather changes.

This has become even more pertinent following the bad, wet and windy weather we’ve recently had and news out of Northern Italy that Psa infection in Italy this spring is higher than previous years.

After a very wet autumn, the Italians have had a relatively mild winter and dry spring. It’s thought that the extensive rain last autumn has led to the outbreak they’re seeing now which is affecting Hayward in particular. Verona, Piedmont and Emilia Romagna are also heavily infected with significant secondary symptoms.

There’s a strong chance we could see the same symptoms here in New Zealand next spring if growers don’t take the right action now. To help protect their orchards, growers need to:

• apply a copper spray following the recent wet windy weather (ensure a suitable time window before harvest) to protect new wounds and rebuild protective cover across vines as soon as possible,
• ensure a copper Actigard spray is applied immediately after harvest to help prevent Psa entering vines through harvest wounds and leaf scars,
• look at a winter copper programme of five full rate copper sprays between harvest and bud break. Consider both weather and orchard activities when planning these sprays.

Post-harvest, Actigard can be tank mixed with copper and is most effective when applied to leaves that are still in good condition. It should not be applied to vines that have been waterlogged for an extended period. Vines should be given four to five days to recover from the recent heavy downpours before application.

For more information, refer to KVH's Psa-V Best Practice Guide.

Any growers concerned they may not be achieving the expected levels of Psa control from copper applications at label rates should contact KVH on 0800 665 825 or email [email protected].