Kiwifruit crops at risk

HELPING HAND: Kumeu orchardist Fiona McRae, with her at-risk crop of 16A gold kiwifruit, appeals to the public to be vigilant. The Psa kiwifruit disease is harmless to humans.

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Growers are moving to protect their crops amid fears that the kiwifruit killing disease found in south Auckland just before Christmas could reach Rodney orchards.

The industry is reeling from the impact of Psa-V in the 15 months since it turned up in a Te Puke orchard in the Bay of Plenty.

The rampant bacterial disease has infected 939 orchards – mostly in the Te Puke region, and is seeing growers elsewhere scrambling to protect their orchards.

The industry is worth around $1 billion to the country annually in exports and production is expected to be down by nearly 20 percent this year because of the disease. Four orchards in Waiuku, south Auckland, were confirmed infected just before Christmas.

That has prompted growers in north Auckland areas to urge the public to help protect their properties and their livelihoods. Signs near orchards will warn people against entering without prior permission.

"There are 130 orchards in the wider Auckland area and 23 registered orchards in the north from Riverhead, Kumeu, Coatesville, Helensville and one at Pt Wells near Omaha," Kumeu kiwifruit orchardist Fiona McRae says.

The disease affects green and gold kiwifruit but the gold varieties collapse the fastest once infected while green varieties like Hayward can still produce fruit.

Ms McRae is also an Auckland/Franklin regional Psa committee member.

The 5.5ha orchard owned by her and partner horticultural contractor Bruce Aitken is planted in 16A and G9 gold kiwifruit varieties.

They were shocked at what they saw during a trip to devastated Italian orchards with a group of 20 growers and packhouse representatives visting Latina last year.

"We came back absolutely devastated," Ms McRae says.

"We left the clothes we'd visited orchards in behind, and washed and wiped down everything else thoroughly. We even wiped down our passport covers – it was just terrifying."

Italy's temperature extremes which sees 5degC frosts and 35degC summer heat made it harder for the disease to spread. But the optimum temperature of 15 to 20degC for the disease closely matches our general temperatures so it has been able to spread much faster here, she says.

Mr Aitken gave up his business to work fulltime on the orchard because of the risk of spreading the disease as a horticultural contractor.

"The disease will stay alive for several weeks in plant material and several days on hard surfaces like blades," Ms McRae says.

So using orchard machinery and shelter belt trimming equipment at different sites carries risk.

"One of the problems for green growers is the high cost of implementing preventative measures, because the growers don't have big margins," she says. "Measures like paying a contractor an hour's labour to clean their equipment after each use makes it difficult."

Not every vine in an orchard becomes infected so they disinfect secateurs after pruning and also disinfect their shoes.

It seems likely the disease won't be contained indefinitely, and with no quick fix on the horizon slowing or stopping the spread becomes more urgent to "buy time", Ms McRae says.

"Everyone is scrambling basically to catch-up and work out how to live with Psa. We're hopeful we will be OK next season as well. By then the industry might have come up with resistant varieties or different root stocks."

This area is also a stepping stone to orchards further north with 48 orchards around the Whangarei area and 103 around Kerikeri covering about 500ha.

No cure has been found despite more than $6 million spent on research and development programmes by the industry. There are important steps to follow if you are travelling to the Bay of Plenty or to south Auckland and you intend to visit a kiwifruit orchard, Ms McRae says.

"Before going on to any orchard either by car or on foot, it is very important to contact the owner/manager for permission to enter. Then stay on the main hard track and only use designated parking areas for your vehicle. Before you leave the orchard, wash your footwear and check your vehicle – especially the wheels – for plant debris and remove it.

Most importantly, don't take any kiwifruit plants home with you. All kiwifruit plant material, as well as vehicles and other hard surfaces, has the potential to carry the disease," Ms McRae says.

If you have kiwifruit growing at home check for spots and dieback.

Visit www.kvh.org.nz for information. Check any kiwifruit vines in your garden and if you find anything suspicious email psaauckland@gmail.com.

- © Fairfax NZ News