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Beetle Battles

Tuesday, April 1, 1997
filed under: Insects

Glenfield, N.D., brothers Jeff, Jon and Ronn Stangeland take the Boy Scout motto — “Be Prepared” — to heart when it comes to scouting their sunflower fields for potential insect problems. Though the Foster County producers haven’t contended with many bugs the past couple years, they believe in scouting for insects several times during the summer.

The Stangelands’ sunflower acreage fluctuates between 1,200 and 2,000, with the majority planted to confections. They’ll typically treat for the sunflower beetle — a seemingly perennial problem — in June; then scout for the banded moth and seed weevil as the crop moves into bloom. “The sunflower beetle has been the main pest we have had to control,” Ronn reports regarding the past two seasons, with neither the banded moth or seed weevil attaining levels requiring treatment.

Phil Glogoza, North Dakota State University extension entomologist, says that’s been a typical scenario of late. “Sunflower beetles continually pose problems around the first of June,” Glogoza says. “The seed weevil has not been a problem in the last couple of years in North Dakota, likely due to environmental conditions. We suspect that the cool springs bring their populations down, and increased soil moisture hinders survival of the larva.”

Scouting fields at critical times during the season and applying the right insecticide before insects become a major problem are keys to good pest management, according to Glogoza. Since different pests infest the fields at different times during the growing season, it’s important to remain alert and be prepared to take action as soon as a problem arises. In North Dakota, the four most common problem insects in sunflower are the sunflower beetle, red seed weevil, the banded sunflower moth and the spotted stem weevil.

While it can be difficult to predict which insect(s) will cause significant problems in a given year, damage can be minimized by early detection through scouting, Glogoza emphasizes. “Scouting allows farmers to do a timely application of insecticide to get optimum results before insect damage occurs,” he states. “Scouting can also help growers avoid unnecessary insecticide treatments if their fields don’t have high enough population of insects. Farmers should apply an insecticide when economics justify the application.

“Growers should scout their fields every week for damaging insects,” Glogoza advises his state’s producers. “It is especially important to scout fields during the critical times of the season when we anticipate major pests. Start scouting for sunflower beetles in the beginning of June, for stem weevils in the first part of July, and for banded sunflower moths and seed weevils in late July or early August.”

The NDSU entomologist suggests taking a look at which insects caused problems in the previous growing season to provide an idea of which ones may be trouble makers again the next year. “If there was a high population of insects in the area at the end of a season, there’s a good chance they will cause concerns again the following year,” he explains.

NDSU’s extension insect management guide lists methyl parathion and pyrethroids like Warrior, Asana, Scout Extra and Baythroid as insecticides that effectively control the above-noted sunflower pests.

The threshold at which growers must decide whether it’s economical to spray for a certain pest depends upon whether one is growing oil-type ’flowers or confections, Glogoza points out. Oil sunflower can “tolerate” more seed damage at market than can the confections, whose set standard for injury is three percent. Regardless of the type of sunflower grown, however, scouting is critical to the success of any treatment program.

“With confection sunflower, we need to be extra careful of normal pests — so scouting and treating are essential,” according to the Stangelands. “Our confection sunflower seeds need to be of the highest quality, compared with oil seeds that can tolerate more pest damage.”

The Stangelands began applying Warrior, a third-generation pyrethroid, when it first became available for use on sunflower in 1995. “We decided to try Warrior because of its longer residual,” says Ronn. “Warrior has shown us excellent control of the sunflower beetle, which is the main pest we have been trying to control between the middle to end of June.”

According to Richard Zink of Wholesale Ag Products in nearby Carrington, N.D., this newer product has held up well in some tough weather conditions. “In 1996 we had a lot of rain, and Warrior showed us good control of the sunflower beetles (adults and larvae), regardless of the weather conditions,” Zink reports. “Many of our growers like the longer residual control of pyrethroids compared to methyl parathion.”

This article was prepared and provided by GrowthTech Communications, a division of Gibbs & Soell, Inc.
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