Waikato’s kiwifruit sector is in lockdown as fearful growers rally to fight the potentially devastating disease Psa after the virulent strain was discovered in a Waihi orchard.
Richard Glenn, a Hamilton grower and co-ordinator for Kiwifruit Vine Health, the biosecurity body created last year to fight the bacterial disease, says Waikato growers were "rocked" by the discovery last week.
The infected Hayward green variety orchard is south of Waihi township and not strictly in the Waikato, he says, but the fact the disease has "jumped" 70km from the previous priority zone of Te Puke, is of great concern and demands a full response from local growers. It may have entered the orchard on plant material or equipment. Glenn says it could have been there for months.
There are more than 100, mostly green kiwifruit, orchards in the Waikato, he says. Growers still have income from this year’s harvest, but the $1.5 billion export industry fears much of the crop could fail next year.
Glenn locks his orchard gates at night, says he is "verbally abusive" to any unscheduled visitor because it means they have ignored large biosecurity notices, and visitors, beekeepers, industry consultants and workers who have come directly from the Bay of Plenty must have completely changed their clothes and in some cases, showered before they visit. Cars are no longer parked in orchards and trucks are sanitised. Growers have taken to buying their own pruning and other equipment to avoid the risk of vine contamination from contractors’ gear, he says.
One big Waikato grower has introduced an ID system for all his workers, Glenn says.
Psa-V, as the most lethal strain is called, has caused large-scale orchard destruction in Italy. A new cause for alarm is that Psa-V will not "shut down" some of the year, as it does in Italy, Glenn says. "It operates between 12 and 20 degrees [Celsius] – which is Bay of Plenty in a nutshell. In Italy it shuts down for four months in summer but we don’t know what it is going to do here."
Psa was first seen in Te Puke in November last year. New Zealand Kiwifruit Growers president Peter Ombler says the problem has reached "crisis" proportions with 262 orchards – all but three in the Te Puke region – or approaching 8 per cent of all orchards in the country having Psa-V. A total of 353 orchards or 10.6 per cent of the sector have tested positive for a strain of Psa.
Zespri says on average 17 Te Puke orchards a week are being identified as having Psa-V.
Hayward green fruit gets Psa-V as easily as gold fruit, but manifests itself more slowly, Glenn says. If the Waikato has any advantage it is that orchards are scattered from each other, unlike Te Puke where they are cheek to cheek, allowing for easy Psa spread.