Hot spots emerge in eastern and southern parts of the state
By Oregon Department of Agriculture
Now is a critical time for farmers and ranchers in eastern and southern parts of the state as millions of young grasshoppers emerge, prompting the Oregon Department of Agriculture to advise landowners to take some action of their own to protect crops and rangeland. In just a few short weeks, the tiny grasshopper nymphs now hatching will become fully developed adults with wings, which could intensify the damage done by the plant-eating insects.
“We are at the beginning of the grasshopper season when they literally pop out of the ground after hatching,” says Helmuth Rogg, supervisor of ODA’s Insect Pest Prevention and Management Program. “This is also when they cause extensive damage because all they really do right now is eat, eat, and eat.”
That eating will continue as they become adults, but the bigger threat is their ability to fly once they mature. Infestations will grow geographically into large areas. Egg-laying females could then create a bigger headache for next year as they distribute the grasshopper population over a wider expanse.
The hot spots at this time include parts of Baker County- a repeat of last year’s outbreak- the Klamath Marsh area, and in Lake County. The species of concern- Camnula pellucida or clear-winged grasshopper- has popped up in Eastern Oregon for the past three years after a 20-year hiatus. For the Klamath Marsh and parts of Lake County, Camnula pellucida has been a more frequent pest.
Eight grasshoppers per square yard are considered enough to cause economic damage. In some areas, there can be up to a thousand of the tiny nymphs per square yard now emerging in the hot spots.
“Once they become adults, they will fly for miles to look for food,” says Rogg. “As soon as they run out of grass, they will go after alfalfa, wheat, and even potatoes.”
No longer able to utilize a large-scale federal program to control grasshopper outbreaks, Oregon ranchers and farmers are strongly encouraged to take matters into their own hands. ODA, with help from Oregon State University’s Extension Service and the US Department of Agriculture’s Animal Plant Health Inspection Service (APHIS), has scouted the hot spots and pinpointed their locations.
“Our survey technicians have been on the scene to determine where the grasshoppers are hatching, when they are hatching, and what landowners can do,” says Rogg.
Once again, the treatment of choice for grasshopper control is the pesticide product dimilin, which acts as an insect growth regulator. When treated grasshoppers molt, the production of chitin- necessary for the development of the insect’s exoskeleton- is impaired. Malformation is common. Within a few days after treatment, molting grasshoppers die. Dimilin is less toxic for non-targets than other hopper insecticides. There is no direct harm to birds and bees flying in the area, or other adult insects.
“I know of one rancher near Baker City who has already sprayed dimilin after noticing that the nearby road was black with young grasshoppers,” says Rogg. “I also know of two neighboring ranches in Lake County covering about 7,000 acres that will be proactive and actually do some aerial application. Last year, they lost a lot of alfalfa to grasshoppers and had to purchase a great deal of supplemental feed.”
Waiting a couple of weeks to apply dimilin will greatly diminish the desired results. Too many grasshoppers will be in the adult stage by then and will be unaffected by the treatment. Subsequent treatments would have to involve malathion or carbaryl bait to be effective against adult grasshoppers.
Another key is convincing all landowners in an infested area to treat the problem. The first of the most recent outbreak in Eastern Oregon took place near Haines two years ago. Some growers took quick action and applied malathion on their property. But the grasshoppers persisted because some neighbors did not treat and the hungry insects simply hopped over the property line and re-infested the treated area.
Local farmers and ranchers who did treat last year are hoping to rally others who did not.
“It can be very expensive to battle grasshoppers,” says Baker County’s Jan Kerns, a State Board of Agriculture member whose family operates a three generation farm that produces cattle, alfalfa, and potatoes among other crops. “Those with high valued crops took protective action last year. What we could lose in crops would be a much greater expense than the cost of treatment.”
Anyone who has not experienced a grasshopper outbreak can still appreciate the vivid stories of impact from those who have battled the pests.
“Last year, we visited one field of grass that had grown very high at the edge of the road,” says Kerns. “I assumed it had not been touched by the grasshoppers. But walking farther into the field, we found huge bare spots. We could hear the eerie sound of grasshoppers eating. It sounded like high transmission lines.”
Kerns can relate the times she has been swarmed by grasshoppers after walking into a field under attack. Last year, she also planted a trial plot of corn at the edge of an alfalfa field. One day, the crop looked fine. On the very next day, the entire 40 foot perimeter of the corn field was black with grasshoppers.
She and others in the Baker and Keating valleys are hoping the recent wet and cool local weather produces some mortality in the emerging grasshoppers, or at least buys some extra time for treatment.
In the meantime, ODA is providing two four-wheeled ATVs equipped with spray tanks that can be used by private landowners to borrow for treating grasshopper hot spots with dimilin. The vehicles will be on loan to the Baker County Extension Office for now.
It’s hard to say whether this year’s grasshopper infestations around the state will be worse than last year. But quick action by farmers and ranchers can greatly reduce this year’s damage and set the stage for improvement next year by preventing millions of grasshopper eggs from being laid this summer.
For more information, contact Helmuth Rogg at (503) 986-4662.
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