Big Crop of Soybean Aphids in 2005?

Some entomologists are predicting we’ll see a lot more aphids chewing on soybean plants this coming summer than we did in 2004. Rod Swoboda

Published on: Jan 21, 2005

There’s a lot of discussion at meetings this winter about the potential for aphids to infest soybean fields next summer. Some entomologists are predicting major numbers of this insect pest showing up in soybean fields in the major Midwest states in 2005.

The soybean checkoff has funded a lot of work the past several years to come up with better ways to control this insect, says David Wright, director of production technologies for the Iowa Soybean Association.

The North Central Research Program is a cooperative program of 12 soybean checkoff boards in states in the Midwest. It is the second largest investor in funding aphid research in the United States, exceeded only by USDA. Projects today involve eight of the 12 states in the Upper Midwest.

Use thresholds to decide when to treat

"We’re looking at two different research areas," says Wright. "The first one is the development of an economic threshold that is practical and accurate. The thresholds in use today are there because of research funded by the North Central Program. The threshold of 250 aphids per plant is when a grower should start spraying immediately. Or 100 aphids per plant if the grower has to call the elevator or other local custom applicator and be put on a waiting list to spray."

These threshold guidelines are available for farmers and crop consultants to use to make good decisions. "We have these guidelines as a direct result of research," he says. "They will likely evolve and be fine-tuned over the next couple of years. One of the things we’re finding out is that yield loss is not quite uniform across the various growth stages of the soybean plant."

"What we are doing now, in terms of research, is looking at an invasion of aphids later on in the growing season. What impact will that have on yield? What level of aphids would we need to control if they infest the field at this later period?"

Keep tabs on soybean aphid next summer

The other key area of research is looking at biological controls. Basically looking at what other insects out there that are predators of the aphid and how can we use those predators to keep the population of aphids low. Today, the only biological control insect out there that feeds on aphids is the Asian lady beetle.

So what researchers are doing? "One thing we’re looking at are areas of China, to see how they control this pest and to try to identify additional predator insects over there that we can bring to the United States to control the aphid in soybean fields here," says Wright.

Many people are predicting a pretty good size crop of aphids in the summer of 2005. Where can you go to learn more information about aphids as you approach the 2005 growing season and throughout the growing season? "Go to www.planthealth.info," says Wright. "That is the best and most widely cited source of information on soybean aphid research and recommendations."