Mite vs. Mite: Controlling Hop Pests Sustainably

 Hop growers battle pests every year to bring a healthy hop crop to market, but a Netherlands-based firm believes bugs can be more effective than chemicals in controlling them. A 2017 trial in Independence used beneficial arachnids to control two aggressive hop pests: the hop aphid and the two-spot spider mite. Results are encouraging and could bring more sustainable solutions to Northwest hop farms.

With a focus on beneficial arachnids and other sustainable mitigations for pests, diseases and other threats to crops, Koppert Biological Systems works with growers in more than 80 countries. The company has recently grown its operations in this region.

“It’s like creating a balance between good and bad in nature,” says Greg Estes, a technical service representative with Koppert who focuses on the Northwest. “All these solutions are on the market now, and we’re just dialing in what works best for the climate and hops.”

Koppert’s Integrated Pest Management (IPM) tries to control or eradicate pests with as “little damage as possible to people, the environment and beneficial organisms.” In addition to regular field monitoring, crop sanitation, cultural and mechanical control, and the introduction of beneficial insects and mites, Koppert tries to prevent the use of chemicals — or at least keep them in reserve as a last resort.

“Hops interest me a lot, with my interest in microbrews and having met some of the growers,” explains Estes. “My research into the crop led me to look at what pests hop growers deal with year in and year out, and those were a lot of the same ones Koppert deals with. The battle is against the two most common pests: the two-spot spider mite and hop aphid. We have a lot of experience with those two pests.”

 The two-spot spider mite can reproduce quickly, and thrives in hot, dry conditions. Given the hop bine’s ability to grow to up to 30 feet, it’s challenging to get sufficient chemical coverage to combat the arachnid. “We use a predatory mite that can co-exist in the plant without the grower having to use the chemicals,” explains Estes. “Our mite can climb the same as the other. The insect application is the only step that needs to take place.”

Based outside of Portland, Estes has spent the past two years getting to know hop growers — and hop pests — in Oregon, Washington and Idaho. From there, Estes collaborated with Koppert scientists and management to develop mitigation protocols, then began talking with area growers about trial runs of these alternatives to chemical pesticides, and to provide options for both organic and conventional hop growers.

In 2017, a farm in Independence agreed to a trial — and to “have faith that we could find a solution without using chemicals,” says Estes. “It took four to six weeks before we started seeing positive results.”

Ultimately the grower was pleased with the results — though it also takes a mindset shift, says Estes. “When you’re going through a conversation about using beneficial insects, it’s a different landscape if you’re accustomed to using chemicals,” he explains. “Chemicals have a quick visual response, usually 24 hours or less. A couple of days after you spray, you can see a substantial decline in pest presence. Insects require more patience, more know-how of what you’re scouting for.”

Koppert assisted the grower through the entire season. “We were there every week working with growers directly,” says Estes. “We monitored for tipping points, or times when farmers needed to use spray, but without totally taking away what we were doing.”

Normally, the grower would have sprayed up to four times in a season for spider mites. “Our trial did only one,” says Estes. “Our next goal will be to get to where we can get to zero sprays.”
Acknowledging a grower’s concerns about cost, Koppert’s intent is to have a farm’s budget for IPM be in line with what they might spend for conventional controls. “Typically speaking, farmers all have a per-acre budget in mind,” says Estes. “We think we have something they can do for a similar budget, without having to use spray.”

After attending recent hop grower conventions, Estes is seeing increased awareness of and interest in Koppert’s IPM methods. Estes is working on arranging more trials in the Northwest this year. “The more experience we get, the better we get,” says Estes. Given the area’s diversity of climates, soils, pests and hop varieties, Koppert is trying to address as many scenarios as possible.

“Bio-friendly methods should be a common method in three to five years,” says Estes. “That can be for diseases too, not just pests. Legislative pressures are mounting on farmers to cut down or stop using hard chemistries. It’s a difficult transition, but necessary, and we’re excited to be part of helping people grow.”

Throughout 2018 he expects Koppert to continue to refine and improve the effectiveness of the protocols.

“We want to limit or eliminate the need for harmful chemicals to grow healthy plants,” says Estes. “We think a right solution can be found using beneficial insects. The benefits are also successful because pests can’t develop resistance to insects like they can to pesticides. An insect can’t develop a resistance to being eaten.” •



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