Extension specialist to study grasshoppers' impact on pulse crops

Reagan Cotton

MSU News Service

BOZEMAN - Through new funding from the USDA and the Montana Department of Agriculture, a Montana State University scientist will study the impact of grasshoppers, an increasingly common pest in Montana, on pulse crops and forages.

Hayes Goosey, assistant professor in the Department of Animal and Range Sciences in the College of Agriculture and an MSU Extension specialist, received roughly $330,000 through the USDA's Specialty Crop Block Program, which supports research into the viability of crops such as fruits, vegetables, tree nuts and pulses. By examining the dietary preferences of grasshoppers, Goosey said, specialists will be able to make more precise and effective management prescriptions for growers.

"There are a lot of people who are trying to venture out into growing different types of forage," he said. "So, this doubles up with a need to look at grasshopper feeding preferences on different crops. The interest in pulse crops as forages creates the opportunity to look into that question."

Grasshopper populations follow drought, said Goosey, meaning that recent drought years in 2021 and 2022 have made the insects more of an issue in Montana, particularly east of the Continental Divide. Grasshoppers are highly attracted to spring and winter wheat, and there are three primary species that pose a threat in Montana: the migratory, clear-winged and two-striped grasshoppers. When droughts are particularly severe and rangeland acreage becomes dry, they will often migrate toward irrigated crop fields.

Goosey recommends scouting fields to estimate grasshopper prevalence. As grasshoppers mature, they progress through five instars, or stages, each of which requires the shedding and regrowing of an exoskeleton. Adults then lay eggs that can overwinter in the ground until the following spring.

Scouting in the spring, when grasshoppers are smaller and younger, allows for more effective management, said Goosey.

"Crops can tolerate a lot more of the smaller first and second instars," said Goosey. "Around August is when they migrate, so July to August is when you're looking to scout adult populations. If you've got adults in the later part of the year, that's where they're going to lay eggs and where you'll have a higher population in the spring."

Goosey said the most effective and commonly recommended management tool for grasshoppers in Montana is a product called Dimilin. Because it targets chitin, which makes up grasshoppers' exoskeletons, Dimilin has little impact on non-target species including rangeland pollinators. And because grasshoppers are so transitory, treating strips or sections of cropland means they will likely pass through, eliminating the need to treat an entire field.

In his new research, Goosey will explore grasshopper feeding preferences among pulse crops, such as lentils and peas, as well as other forage crops. In identifying plants that are particularly attractive to the insects, Goosey said those can then be used as "trap crops," drawing pests away from main crop fields and further narrowing the acreage that may need to be treated with deterrents.

The project will fill an identified knowledge gap around how grasshoppers interact with pulse crops, said Goosey. The USDA National Agricultural Statistics Service estimates that more than 1.1 million acres of pulse crops were planted in Montana in 2023.

"This will be a way to protect pulse crops and to expand knowledge about grasshopper feeding on pulses and non-pulses," he said. "Right now, we're educating on what we know, what the options are and what programs are available."

One of those programs comes from the USDA's Animal and Plant Health Inspection Service, or APHIS, which often helps to cover the cost of grasshopper control on federal, state or private land. Goosey said combining new research into the best practices for Montana with public education to ensure producers know what resources are available will help to ensure the most effective response to grasshoppers and other pests.

"At the end of the project, we'll be able to rework recommendations with feeding preferences, plant seeding rates, chemical products and different control options, and update what we know here in Montana with what we've learned with this project," he said.

For more about MSU Extension Animal and Range Sciences, visit the MSU Extension website at https://animalrangeextension.montana.edu/forage/index.html .