30 Jan 2012

Trial shows no effective PSA treatment for gold kiwifruit

8:04 am on 30 January 2012

The first field trial of treatments used to shield gold kiwifruit from the vine disease PSA has shown there's no silver bullet for protecting the vulnerable variety.

Kiwifruit Vine Health says PSA-free vines were given different treatments, then placed in a Te Puke orchard infected with the disease.

The healthy vines were sprayed with water encouraging Psa to spread to them.

Two treatments, including hydrogen peroxide, had no effect in protecting the vines.

Most of the other treatments, including the common KeyStrepto, delayed the infection but didn't stop it.

But Kiwifruit Vine Health says it will continue trials to investigate the effectiveness of repeat applications.

New gold variety planned

Kiwifruit Vine Health says yellow-fleshed kiwifruit won't disappear from supermarket shelves despite its vulnerability to PSA.

The gold variety, Hort 16A, attracts better returns than its green counterpart, accounting for a quarter of the national crop and a third of the value.

However it has proved the most susceptible to PSA, and in Te Puke, where half the country's gold variety is grown, 90% of the vines have been infected.

Kiwifruit Vine Health general manager John Burke says while Hort 16A may not survive, other gold varieties will replace it.

He says if the plan works there will be a gradual phasing out of Hort 16A, which is the traditional gold, to a new gold called G3.

Mr Burke says they don't want all growers around the country to pull out their Hort 16A, so there will be continued production from the outlying regions and the new gold will be introduced over the next two or three years.

He says gold kiwifruit production will probably halve this season to 15 million trays.

PSA has infected nearly 1000 orchards since it was first found on a Bay of Plenty orchard in 2010.