Soybean aphids and K-deficient soybeans: Why are there aphids in my field and not my neighbor\u27s?

There were frequent reports of fields infested above 250 soybean aphids per plant adjacent to those with lower populations that never reached threshold. The lowest aphid populations were seen in the southern tier of Iowa counties. However, Mark Carlton, extension field crop specialist in southeast Iowa, called me several times during the season to report that he had scouted fields that were above threshold. By the third call, it became a bit of a routine, with each field sharing some remarkable similarities