August 2010 - Vol 96 No. 08 

Asian invasion a reality in OK
50 cases confirmed at 22 sites in the valley

by WENDY JOHNSON
OLIVER – The speculation is over; now the worry and vigilance begins. Spotted Wing Drosophila (SWD) has been found in two locations in the Oliver area. That unwelcome news was delivered to a group of growers gathered at Greg Norton’s home orchard on July 14.
“We have two confirmed males that were captured in traps,” stated Okanagan Tree Fruit Co-operative (OTFC) fieldperson, Lindsay Hainstock. “One was from around Black Sage Road and the other one was found on Road 7.”
Those were words soft fruit growers had dreaded hearing ever since they learned about the new vinegar fly that lays its eggs in harvest-ready soft fruits such as cherries, peaches apricots, plums, nectarines, grapes and berry crops. With its penchant for five-to-seven generations per season, SWD has the potential to wipe out a good segment of the fruit industry here.
“This is serious and I’m worried,” commented Andre Miller, who has both cherries and grapes.
A native of Japan, SWD was first detected in California in 2008; since then it has claimed orchards and vineyards throughout that state and moved on to conquer crops in Oregon and Washington before appearing in the Fraser Valley and Central Okanagan last year.
In an effort to head off or at least mitigate the destruction, the Okanagan Kootenay Cherry Growers Association applied $25,000 toward a trapping and weekly monitoring program this spring and now the first results of that program are re-affirming their fears.
“It’s here, man, it’s here,” groaned Greg Norton when he heard the news. “We received money from various sources and now have 343 traps up and down the valley. To date we have confirmed 50 positives from 22 different sites,” OTFC field service manager, Hank Markgraf, told the group. “Until now, it’s basically been found in the more humid and wetter areas, but now that we’ve found them here, this throws that observation out the window.”
The whereabouts of those spotted wing drosophila finds haven’t been made public yet; the affected growers will be notified locally by Charlotte Leaming, one of the program’s co-ordinators at OTFC, who will then discuss specific controls with those individuals.
But the discovery will change the way soft fruit growers manage their crops from this point onward. Accustomed to one-generation pests like cherry fruit fly (CFF), farmers have built their spraying, maintenance and monitoring programs around those assumptions, but SWD is yanking them brutally out of that management regime.
Although four pesticides – Delegate, Entrust, Malathion and Ripcord – have been given emergency registration to control SWD on stone fruits and grapes until October 31 this year, there are numerous hurdles ahead. All are toxic to bees and Malathion may be phytotoxic to some cherry varieties. Pre-harvest application rates and intervals, registration limitations on other pests, coverage and re-entry days, plus export acceptance all differ with these pesticides and must be taken into consideration.
And this was the main thrust of the conversation under the trees as several growers, packinghouse and growers supply staff and the B.C. representative of Dow AgroSciences mulled over the negative ramifications of drosophila’s appearance.
“We don’t know how persistent it will be in the growing season, but with this monitoring program we’re hoping to get a jump on it and be aware of the potential downfalls for us in trying to grow our fruit,” noted Markgraf. “I don’t want to create a panic here and have everyone go out and spray willy-nilly. What we want to get across is you need to be aware of what’s going on in your orchards and neighbourhoods.
“If you don’t have traps, get some. Add about one inch of apple cider vinegar as an attractant and monitor for spotted wing drosophila. If you are doing your own monitoring and are confused about what you find, ask our field staff.” For those who find themselves close to already affected farms, he had a word of advice: "I would say control as you normally would for cherry fruit fly and pick one of the products that will cover both."

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