An arachnid that looks like a small black spider with reddish legs is causing problems in northern Washington wheat fields. Millions of these bugs are rasping the fresh wheat leaves, damaging the plant and sucking up the wheat juice. These arachnids, called winter grain mites, like a cool, mild winter, and that’s what they’ve experienced in Washington state recently.
That’s led Washington State University to issue a warning about the pests.
To try to solve the problem, many farmers are now bombing the mites with pesticides using planes. That's expensive, especially in a year when wheat prices are down, said Jamie Douglas, a 27-year-old farmer from Lincoln County, Washington.
Farmers aren’t sure how much to spray to get rid of the mites, said Aaron Esser, a regional extension agronomist with WSU.
One grower told Esser he was going to spray half his acreage and let his yields tell him what to do next year. Some spaying can be more than $10 an acre, plus chemical costs of around $7 an acre. That adds up quickly when many farmers are dealing with thousands of acres to make a livelihood, he said.
“There is no doubt that it’s stressful,” he said. “But what you don’t want is a really good crop taken out by something you could have impacted. You still need to get yield.”
Esser said his phone has been ringing earlier and more frequently than it has in a long, long time. He hopes that farmers will be more prepared to identify the mites early next year.
“There’s a distribution of reactions,” said Douglas. “Some people are emotional about it and say, ‘I’m absolutely not going to spray ‘cause we’ve never had to spray before’ … and on the far end of that, others decide to spray every acre. I just try to stay somewhere in the middle, I guess.”
Warmer winter, and when mites might come back
The mites leave behind sucked-dry fields that are silver, brown or gray. Many different types of these mites attack crops, said David James, an associate professor of entomology at WSU’s Irrigated Agriculture Research and Extension Center in Prosser. He’s studied mites on crops in Australia. James surmises that this year’s mild winter helped the mites flourish in Washington.
“These mites are winter mites,” James said. “It’s very odd for us to have such a mild winter … And in those conditions, these mites just go crazy. They do extremely well.”
James said the mites can be identified by the tiny hairs on their backs. The mites die off when temperatures increase, and eggs live in the dead mothers’ bodies through the heat of summer. They could hatch and thrive again if there’s another mild winter.
“They are extremely well adapted to a climate that has a very hot, dry summer, and a mild winter,” James said.
Spot check
Now, there are millions of the arachnids turning farmers’ fields brown. A quick spot check of other growers throughout the state showed the problem isn’t likely widespread throughout the state but is mostly concentrated north of U.S. Route 2 in Lincoln County, Washington.
Climate change could also be a problem going forward, James said.
“If winters like this are more of the norm, we’ll see these mites become more of a problem that farmers would have to treat,” he said.
Douglas said he’s trying to keep a cool head with these mites, but it’s been stressful to deal with this new wheat foe.
“It’s frustrating to have to go spend a bunch of money right now to go out and spray something that we’ve, in my knowledge, we’ve never had an issue with these before,” he said.
