Soybean aphid outbreaks are not predictable at planting time, so aphid-resistant seeds are a good choice for growers in regions where infestations are common, says Matt O’Neal, Iowa State University (ISU) entomologist.

Outbreaks depend on the weather and other factors, such as natural predators, he says. However, damaging infestations tend to be more common in South Dakota, Minnesota and the northern half of Iowa, and in areas with dense stands of buckthorn, aphids’ winter habitat.

Quinn Showalter, Syngenta soybean traits marketing manager, suggests that growers try the technology on “fields that are difficult to spray,” such as those with windmills, terraces or irregular shapes, or fields near buckthorn stands.

Farmers who have sprayed for soybean aphids in two out of the last four years should consider planting aphid-resistant seed, O’Neal suggests.

The premium for soybean aphid-resistant seed may be less than the cost of a foliar insecticide application, says Mike McCarville of ISU’s entomology department. The technology fee for the Rag1 gene ranges from about $1/bag to around $10/bag, according to his January survey of Iowa seed dealers. If you are spraying for aphids half the time, it may be more cost effective to grow an aphid-resistant variety, he says.

Organic soybean producers should also consider planting Rag1 beans, O’Neal says. Aphid resistance genes are native to soybeans: they’re not genetically modified. Phil Batalden, an organic farmer from Lamberton, MN, will be planting a food-grade Rag1 soybean this spring. He’s taking a chance on a 2.3 maturity group, which is late for his area, but it’s the best food-grade choice available this season, he says. “Aphids have been devastating, and organic growers have few, if any, effective ways to manage them.”

Growers looking for a more diversified pest-management approach should consider them, too, McCarville says. These varieties can reduce the need for chemical inputs, especially later in the season.