SEEDS OF DIS­CON­TENT

They’re the fruit we love so much we named it af­ter our­selves – but now, writes Chloe Ran­ford, the hum­ble kiwifruit has grown into a pest that could ruin our na­tive veg­e­ta­tion and major agri­cul­tural in­dus­tries.

Sunday News - - NEWS -

FARMED kiwifruit may bring mil­lions of dol­lars as an ex­port but its wild cousin is be­ing branded a ‘‘hellish’’ pest that’s dam­ag­ing na­tive bush and threat­en­ing the na­tion’s vine­yards.

Kiwifruit Vine Health an­a­lyst and com­pli­ance of­fi­cer John Mather said it was highly un­usual for an in­dus­try to turn in its own pro­duce as a risk.

‘‘It’s not of­ten a mem­ber of an in­dus­try comes for­ward in the hopes of nam­ing their pro­duce a pest,’’ Mather said.

Mather took his case to a pest man­age­ment meet­ing in Marl­bor­ough last week, say­ing wild kiwifruit could threaten the re­gion’s cel­e­brated wine in­dus­try.

‘‘Not only does wild kiwifruit im­pact indige­nous bio­di­ver­sity and pro­duc­tion of forestry, it’s also a reser­voir for dis­ease or­gan­isms such as PSA and pests such as fruit flies and stink bugs,’’ Mather said.

‘‘If th­ese pests or dis­ease got into Marl­bor­ough vine­yards, it could have a detri­men­tal ef­fect on their growth.’’

New Zealand Wine­grow­ers biose­cu­rity man­ager Ed Massey said the brown mar­morated stink bug, a known kiwifruit hitch­hiker, was a ‘‘high-risk’’ threat to the wine in­dus­try.

‘‘Not only do they eat the grapes, but they taint the red wine,’’ Massey said.

‘‘The de­fen­sive chem­i­cals the bugs re­lease when crushed af­fect the red wine juice and its qual­ity.

‘‘Should a pop­u­la­tion es­tab­lish thanks to wild kiwifruit, Marl­bor­ough vine­yards would have a lack of sur­veil­lance and con­trol tools avail­able to com­bat the threat they’d pre­vent.’’

Motueka’s Golden Bay Fruit owner Kerry Wilkins said vig­i­lance in the or­chard was key to prevent­ing wild kiwifruit growth in the South Is­land.

‘‘Kiwifruit that does fall to the ground gets blended up in the mower to pre­vent it from spread­ing else­where,’’ Wilkins said.

‘‘Good hy­giene in the or­chard, like wash­ing your hands, and be­ing vig­i­lant are two cru­cial as­pects to prevent­ing wild kiwifruit spread.

‘‘While it’s a plant that some­times grows in the area, it’s not a big prob­lem right now.’’

But on the other side of New Zealand, in the Bay of Plenty, wild kiwifruit was a much larger is­sue.

‘‘In th­ese ar­eas, wild kiwifruit rapidly forms a heavy blan­ket of growth which kills, or top­ples, na­tive trees and shrubs be­neath,’’ Mather said.

‘‘Since 2010, Kiwifruit Vine Health has killed around 14,600 wild kiwifruit vines in Bay of Plenty and Te Puke.’’

New Zealand Kiwifruit Grow­ers Inc chief ex­ec­u­tive Nikki John­son said kiwifruit grew well in New Zealand be­cause it boasted some of the ‘‘best grow­ing con­di­tions in the world’’.

‘‘Clean air, fer­tile soils, a cool ocean, gen­er­ous cli­mate, and fewer pests and dis­eases all con­trib­ute to the unique qual­ity and taste of New Zealand-grown SCOTT HAMMOND / STUFF seeds per fruit and th­ese have a high like­li­hood of ger­mi­na­tion,’’ he said.

Mather said wild kiwifruit out­breaks were ‘‘ex­ac­er­bated’’ by un­picked fruit.

‘‘Any fruit­ing vines that aren’t man­aged prop­erly are tar­geted by birds who eat the wild kiwifruit and then spread the seeds into ar­eas of na­tive bush, forestry blocks and near or­chards or farms,’’ he said.

Kiwifruit scraps were also said to be a major cause of wild kiwifruit flare-ups.

‘‘We’ve found kiwifruit stick­ers near wild kiwifruit vines, which proves the vine sprouted as a re­sult of some­one throw­ing their scraps out,’’ Mather said.

‘‘What’s in­ter­est­ing is that be­cause kiwifruit stick­ers are changed each year, we’re able to find out in which year the scraps were orig­i­nally dumped.’’

Wilkins said South Is­land kiwifruit farm­ers were con­cerned about a wild kiwifruit out­break be­cause the fruit of­ten har­boured vine-killing dis­ease PSA.

‘‘At the mo­ment, our district is PSA free,’’ Wilkins said. ‘‘We spray farmed kiwifruit for dis­ease con­trol pur­poses, but wild kiwifruit doesn’t re­ceive this treat­ment.

‘‘Ev­ery­one is con­cerned about wild kiwifruit be­cause the PSA it could har­bour would be quite detri­men­tal to the in­dus­try.’’

John Mather is wag­ing a war against wild kiwifruit.

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