The current issue of the Integrated Crop Management newsletter from Iowa State University is devoted to the topic of soybean aphids, including what factors influence their populations field-to-field.
Here's the first part of the "2005 Wrap-up" introduction by Matt O'Neal, ISU Department of Entomology, followed by a list of the articles in the "Special 2006 Soybean Aphid Issue" available online:
"The 2005 growing season left many growers with very different experiences managing insect pests in soybeans. Aphids were feared to return to economic populations, and for nearly 2 million acres in Iowa, they did.
"However, many growers reported fields with 250 or more aphids per plant next to fields that had few if any aphids. I was a bit skeptical of this last observation, but such a situation occurred next to one of our research plots in Story County.
"Just as one would expect, the field that we had carefully marked and planted for research had a sub-economic population of soybean aphids. But throughout July and August, just 20 feet to the north, a 10-acre field of soybeans following alfalfa reached several thousand per plant by the first week of August.
"For more on why this neighboring field may have suffered from aphids while the one we were working in did not, see "Soybean aphids and K-deficient soybeans," page 6. So, aphid populations were at times spotty but significant. What lessons can we draw from the 2005 growing season, and how should we prepare for 2006?"
Online version of the Jan. 23, 2006 issue
SOURCE: "Integrated Crop Management" newsletter from Iowa State University, Jan. 23, 2006, issue.