Fresh reminder of Psa threat

Kiwifruit growers are being warned not to be complacent about the vine disease Psa, which could be more active this growing season due to the cold winter.

'Psa may be more significant this season than it has in the last couple of years,” says Kiwifruit Vine Health (KVH) operation manager Peter Mourits.


Photo: File.

'We have seen some early signs of the disease in Waikato and Waihi orchards, but it's too early to tell how serious it will be.”

KVH will be sharing that information with growers at a meeting in Te Puke tomorrow (Wednesday) and advising them to be vigilant for any signs of infection.

'Growers need to get out in the orchard, especially once sap flow starts, and look for signs of exudate, remove it and follow up with a spray programme,” he adds.

Peter says MetService data shows this winter has been around two degrees cooler than the last three years, and cold conditions favour Psa.

The first day of spring today brought heavy rain and strong winds – conditions conducive to the spread of Psa – but fortunately vines are still dormant which reduces the risk of infection, he adds.

'Since the removal of the most vulnerable kiwifruit variety Hort16A, we have seen inoculum levels drop significantly,” says Peter.

Mike Chapman, CEO of New Zealand Kiwifruit Growers Inc, says most orchardists have finished winter pruning, tying down canes and applying Hi-Cane, which could also reduce the risk of infection.

'We know Psa is about,” admits Mike. 'It's certainly not rampant at present, but we know wet windy weather suits the disease. It's too soon to tell what the impacts might be.”

NZKGI president Neil Trebilco says a bigger risk for growers from the current weather is flooding, but so far he hasn't heard of any orchards being inundated with water.

Since the disease was first found in the Bay of Plenty in 2010, much has been learnt about its management, including spray programmes and on-orchard hygiene.

Growers will be watching vines carefully in the coming months as bud burst and pollination occurs, setting up the vines for next year's harvest in autumn.

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