This crop year has been the most challenging in Nikki Rothwell’s dozen years as Coordinator of Michigan State University’s Northwest Michigan Horticulture Research Center.
First, it was the hottest. Second, it was a huge cherry crop – both tart and sweet – the biggest since 2009. Third, a wicked hail storm hammered the crops of many growers, including Rothwell’s own cider apples.
“At my house (on the Leelanau Peninsula), we have a teeny little apple orchard,” she says, “and our apples got totally shredded.”
But even with all that, it wouldn’t have been nearly so bad if spotted wing drosophila (SWD) wasn’t such an ominous threat. It can explode so quickly, Rothwell says, that growers were spraying almost constantly.
“But even expensive spray programs don’t always work, there’s a lot of hit and miss, it’s unpredictable,” she says. “The pest is a game-changer for the tart cherry grower in Michigan.”
MRLs A Headache
Francis Otto of Cherry Bay Orchards in Traverse City wouldn’t disagree. One of the nation’s largest cherry growers, he farms 1,200 acres of tart cherries and 175 acres of sweet cherries at various locations in the state. The main thrust of his business is supplying Shoreline Fruit with the dried cherries sold at Costco stores.
Because many of those Costco warehouses are outside the U.S, Otto has to cope with the various maximum residue levels (MRLs) for pesticides permitted by other countries. But because he does farm in different parts of the state, he does have some enviable flexibility.
For example, this summer he was able to harvest 300 acres of tarts in Southwestern Michigan early, before SWD really took hold. Those tarts are destined for Europe.
“We’re really fighting the MRL issue,” Otto says. “Trying to keep SWD under control while meeting MRLs was a major problem this year.”
Because it’s cost-prohibitive for him to do blanket spraying, Otto has come up with a strategy in which he sprays alternate middles every three to five days.
“In the past we could stretch it out to 12 days, and it was not much of an issue,” he says. “Now, trying to juggle this is a logistics nightmare.”
He changes materials frequently to avoid resistance problems, and has found that Imidan (phosmet, Gowan) is working surprisingly well with MRLs. “They said you couldn’t use it 14 days before harvest,” he says, “but you can.”
Otto will use the alternate row strategy again next year, as it seemed effective. Despite the really big crop year, and the heat, he didn’t have SWD at a high enough level to be detected. But that doesn’t mean he won’t be watching like a hawk in 2017.
“You absolutely have to keep ahead of the curve; don’t let population numbers build up,” he advises. “You have to keep being proactive about keeping populations under control.”