Keep What Works Working: NZ's New Resistance Campaign
New Zealand growers have always adapted to changing conditions, but one challenge is steadily gaining ground across the horticulture sector: resistance.
Hort16a has been particularly susceptible to Psa with Kiwifruit Vine Health advising growers nationwide to replace it with new Gold varieties, such as G3.
Kiwifruit Vine Health (KVH) chief executive Barry O’Neil says since Psa was found in three orchards in Wanganui, all orchards in the region are being monitored. The Psa was found in the Hayward Green variety, which stands up to Psa better than Hort16a.
“Since there’s no Hort 16a we are hoping that growers, by being proactive, will be able to manage the impacts more easily,” he says.
KVH is testing other orchards where possible symptoms are found but so far none have come back positive. “However it wouldn’t be unexpected that we would find further infection in the region.”
The Psa was found on the river out of Wanganui. In a ‘controlled area’ of a 10km radius around the first orchard identified, there are seven orchards with 38ha of kiwifruit.
The Wanganui find leaves only three kiwifruit growing regions free of the disease – north-west Auckland, Whangarei and the South Island. However one other infected area, Kerikeri in Northland, had only one infected orchard found last year, with none since.
Until the last couple of weeks, Psa has been “relatively quiet” in infected regions nationwide, but the disease becomes active in spring. “We have seen far less Psa than in previous years. Even now it is still less but we are starting to see it move.”
In New Zealand’s main kiwifruit region, the Bay of Plenty, there is little Hort16a left so KVH is not seeing the levels of infection of previous years. “We are benefitting as an industry from a very good summer, a very mild winter as far as freezing and frosts go, less Hort16a and a more proactive approach by growers. It all helped to reduce the amount of Psa.”
