Hot temperatures and extremely dry conditions have existed across much of the Upper Midwest during most of July. These conditions have put the 2006 corn and soybean crop in much of western and central Minnesota under varying degrees of drought stress. This is probably the widest spread drought stress seen in Minnesota since the severe drought-year of 1988. The drought situation is even more extreme in North and South Dakota. Crop conditions are somewhat better in south central and southeast Minnesota, where timely rainfalls have been more frequent and in higher amounts in recent weeks, as compared to areas more significantly impacted by the drought conditions.
A large number of soybean fields in portions of South Central Minnesota have been treated for soybean aphids in late July. There have been numerous reports of aphids in soybean fields. Some were still slightly below the threshold level for treatment, but growers wanted to be sure that they could achieve timely treatment. The University of Minnesota recommends an economic threshold level of 250 soybean aphids/plant before insecticide treatment is recommended. In 2003, and again in 2005, soybean aphid numbers increased dramatically in just a few days during late July and early August, which led to significant crop loss and thousands of acres being treated in Minnesota. Soybean growers are encouraged to continue monitoring fields for the next few weeks for sudden potential increases in soybean aphid counts. They should pay especially close attention to scouting fields if we get more extended periods of hot, dry weather in the next couple of weeks. The early-planted soybeans are ahead of normal development for early August, and should be out of danger from soybean aphid damage in 2-3 weeks. However, later planted soybeans, including soybeans replanted in mid-June, may face potential soybean aphid damage for a more extended time period during August.
Editors note: Kent Thiesse is a former University of Minnesota Extension educator and now is Vice President of MinnStar Bank, Lake Crystal, MN. You can contact him at 507-726-2137 or via e-mail at firstname.lastname@example.org.