The summer drought, a mild winter and good orchard management are being credited with a significant reduction in Psa-V infections - but kiwifruit growers are warned not to become complacent.

'This time last year the industry was experiencing a far greater impact from Psa than we are seeing now, and some orchards were reporting 50 per cent of their vines had excaudate,” says Kiwifruit Vine Health CEO Barry O'Neil.

No new cases of the disease were reported to KVH last week, but 2245 orchards have the disease in some of their vines, representing 75 per cent of the hectares on which kiwifruit are grown in New Zealand.

Pseudomonas syringae pv actinidiae is bacterial disease which can kill kiwifruit vines. The gold Hort16A variety is particularly susceptible but the new gold G3 has shown some tolerance to the disease.

'Psa hasn't gone away and growers still need to be vigilant and keep up protective sprays, but a number of things have worked in our favour in keeping levels down.

'The first is the long hot summer, which reduced inoculum levels, followed by a mild winter. It is known that frost and cold damaged vines are more susceptible to Psa.”

Barry says the removal of most of the highly vulnerable Hort16A gold variety has also reduced inoculum levels.

'Last but not least growers are more proactive in managing the risks to their orchards, including orchard hygiene, how they work in their orchards and their use of copper and Actiguard protective sprays.”

However, Barry warns KVH still expects to see an increase in incidences of the disease as spring progresses.

Overall the drop in Psa levels has engendered cautious optimism among growers and the industry in general, especially as the new variety G3 appears to be performing well, even in areas significantly impacted by the disease.

The focus in the next few weeks will be on male vines, essential for pollination, to assess if they will again be badly impacted by the disease.

Last season Barry says there were real fears that there may not be enough male pollen to set crops, but in the end growers did manage to source sufficient pollen.

Growers are also being advised to take action over cankers, which form on vines as a result of Psa infection and have the potential to spread the bacteria to other plants.

'We are advising growers to cut out or cauterise the canker where possible.”