Sugarbeet root maggot activity to peak soon

Published online: May 01, 2014
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BOISE—Sugarbeet growers in the Treasure Valley area have been alerted that peak sugarbeet root maggot fly activity is forecast to occur the first week of May.

Growers should scout their fields and make preparations to treat their sugarbeet crops for the insect if they haven’t already done so, said Jerry Neufeld, University of Idaho’s Canyon County extension educator.

According to a model that calculates heat degree days, peak flight of the root maggot flies should occur on May 6 in the Treasure Valley, Neufeld told growers in a pest alert.

Peak flight could occur later if temperatures cool down or earlier if they warm up, he said.

Shortly after emerging, the flies will lay eggs at the base of sugarbeet plants and, when they hatch, the larvae will start feeding on the young sugarbeet seedlings.

The alert is a reminder that the root maggot flies will start emerging soon and laying eggs, Neufeld said. “If there was a big problem with this insect, it could be devastating if you didn’t treat for it.”

The maggots emerge at the base of sugarbeet plants and chew on the roots, said Greg Dean, an Amalgamated Sugar Co. agronomist who works with growers in the western part of the state.

If they sever the tap root of seedlings, “the plant will either die or never be a beet that amounts to anything,” he said.

The maggot can cause devastating losses if fields aren’t treated properly, Dean said.

“If you haven’t made arrangements to treat, you should seriously be considering doing that,” he said. “It’s getting close to that threshold.”

The root maggot flies should start appearing in the western end of the valley first because of the warmer temperatures there, Neufeld said.

Peak flight for the flies will occur in southcentral Idaho roughly three weeks after it does in southwestern Idaho, said David Elison, an Amalgamated agronomist who works with sugarbeet growers in the Magic Valley area.

The insect is a problem wherever sugarbeets are grown in Idaho but it can pose an extreme problem in certain areas, including Minidoka and Cassia counties, he said.

“It’s our foremost insect problem, particularly in the Mini-Cassia area,” he said.

Elison said the maggot can kill a seedling or “cause such a problem that it stymies growth for an extended period of time so you lose tonnage and production. If you get a severe infestation, you can lose 10-20 percent of your crop.”

He said sugarbeet root maggot infestations are exacerbated by inadequate control and the severity of the problem “ebbs and flows with the amount of attention paid to controlling it.”