Biological controls to battle disease


New products to help kiwifruit growers in their constant battle against the vine disease Psa-V are likely to start being released next year, says Kiwifruit Vine Health chief executive Barry O’Neil.

Barry, who describes the first of these products as “exciting”, says they have been developed as part of the ongoing Psa research programme run by KVH in conjunction with Zespri Innovation into which $2 million of funding is invested each year.

The research programme was established in early 2011 and has enlisted the best scientific minds globally to provide solutions for Psa-V. The results so far include a ‘toolbox’ for managing Psa-V, and significant progress in understanding plant physiology.

“The research has among its aims to discover what the triggers are for the disease and why we see it in some situations and not in others.

“We want to give growers more tools and more choices at a lower cost, and are also putting effort into finding biological applications. As an industry we don’t want to be overly reliant on copper and other sprays, but to move to more sustainable methods, including biological controls.

Vine girdling

“Kiwifruit growers will probably always have some reliance on copper and other sprays but we want to reduce their application.”

Among the promising and low-cost methods which has proved successful in green varieties is girdling the trunks 30 days before flowering.

“This method has been trialled in the past two seasons and has reduced the incidence levels of Psa flower infection by 50 to 70 per cent.” It’s a method which doesn’t require the use of sprays, only the cost of labour.

The Zespri and Plant & Food breeding programme to find kiwifruit varieties which are even more tolerant of Psa is continuing too.

Grower innovations

Barry says much innovation is also coming from growers who are using their considerable knowledge and observation skills to come up with ways of managing the disease. “Covering orchards with plastic to stop Psa infections was an initiative from growers.”

The bacterial vine disease Psa-V was first identified in New Zealand in November 2010 and Barry says the industry’s response to, and recovery from, the disease is more than impressive.

“It is amazing to think how far we have come in six years and how growers have adapted and responded to the challenges.

“What particularly impresses me is the fact orchard production has increased post-Psa. Green production has gone from an average of 8000 trays a hectare to over 12,000.

“This reflects that growers have ben proactive and focused on their orchards and vine management and have been rewarded for their effort.”


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