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DAVID'S DESK

An update on soybean health issues by David Wright, Ph.D., education director of NCSRP's Plant Health Inititative

Researchers Predicting Aphid Hotspots

You’ve probably heard that university entomologists are predicting high aphid populations in some areas of the Upper Midwest this year. Growers in northern Indiana and Illinois, in particular, may see record aphid levels.

These predictions are based on 40 suction traps that collect migrating aphids during the summer and fall. Unfortunately, the number of aphids captured last fall while migrating back to buckthorn was higher than ever in some locations.

Measuring the migrants
When the number of fall migrants is considerable, it indicates high levels of aphids overwintering – and a potential problem the following spring when soybeans emerge. Traps in Illinois have been running since 2001, so scientists have seen this trend in action three times.

In the fall of 2002, the number of migrating aphids was very high, and 2003 turned out to be a nasty year for aphids. We saw the same pattern again in the fall of 2004, and aphid populations exploded in 2005. In fall 2006, researchers again recorded significantly higher numbers of migrating aphids in some spots.

Suction traps are a means to track aphid overwintering flights. Fall flight activity may indicate the size of the overwintering, and following-season, soybean aphid population. Trap captures can be viewed at the Regional Soybean Aphid Suction Trap Network

Scientists caution that just because one trap count is high, it doesn’t mean every farmer in the Midwest needs to stock up on insecticides. Rather, a high trap count in your area may indicate a localized outbreak. For example, two of five Minnesota traps captured a lot of aphids in 2005, and in 2006, there were aphid outbreaks in those two areas.

Suction trap technology
The suction trap network began in Illinois, and has since expanded to 10 states in the North Central Region. The traps are basically big tubes roughly 25 feet tall – high enough to catch winged, migrating aphids. At the base of each tube is a jar filled with preserving fluid. Fans suck aphids into the tube, and aphids are preserved in the jar.

Every week, researchers replace the jars and count the number of soybean aphids. Results are reported on a Web site, allowing entomologists to track soybean aphids.

Did I mention this is funded by the North Central Soybean Research Program and several state soybean associations? That’s your soybean checkoff. Delivering results.

Information on these pages is from the cooperative effort of researchers throughout the North Central states. Information from this site can be copied and distributed for educational use. Please credit the source with our name and URL: NCSRP Plant Health Initiative at www.planthealth.info. Please do not use copyrighted photos without permission.