Many fields have been sprayed for soybean aphids in the northern part of the area, although aphid populations have been considerably lower than what we saw in 2003. The rains should also help to reduce aphid numbers, and the aphid population should start to naturally decline in about a week. In many fields most of the aphids found recently have been the small off-white aphids, rather than the larger yellow-green aphids. It is the larger aphids that are the biggest threat to rapid reproduction resulting in soybean yield losses, although we should not ignore the small aphids in making treatment decisions. Hopefully spraying for soybean aphids is nearing an end for the season, but fields should continue to be scouted for another week or two for aphids. Treatment is recommended if aphid numbers are increasing and surpass 250 aphids/plant. For more information on soybean aphids see < http://www.ent.iastate.edu/soybeanaphid/> and the July 11, 2005  ICM Newsletter at http://www.ipm.iastate.edu/ipm/icm/2005/7-11/aphids.html.

Asian Soybean Rust

There have been a few more confirmations of soybean rust in the far southern U.S., but no farther north than central Alabama, and no farther west than southern Mississippi. For the latest see http://sbrusa.net/.

CORN

Watch for Corn Ear Rots This Fall

Some corn ears I pulled yesterday in Johnson County had a green mold growing on it that may be Aspergillus flavus, the fungus that can produce aflatoxin. The drought stress increases the likelihood that we will see more problems with the ear rots that produce mycotoxins this year. However, the presence of the fungus does not necessarily mean that the mycotoxin is present. For more information see the October 6, 2003 ICM Newsletter at http://www.ipm.iastate.edu/ipm/icm/2003/10-6-2003/molds.html.

ALFALFA

Late Summer Seeding of Forages

Now that we finally have received some rain, a late summer seeding of alfalfa may make sense for some producers if there is soil moisture to plant into. The target date to have forages seeded by for the best chance of establishment in the central third of Iowa is August 20. Since most common weeds don't germinate well this late in the season, we do not recommend a companion crop or pre-plant herbicide. For more information see the handout "Late Summer (Fall) Seeding of Forages in Iowa" or http://www.exnet.iastate.edu/Pages/eccrops/latesummerforageseed.html

FOR YOUR CALENDAR

Crawfordsville Fall Field Day - September 14 1:30 p.m.

The annual fall field day will be held at the SE Iowa Research Farm near Crawfordsville on September 14 at 1:30 p.m. Alison Robertson and X.B. Yang will be featured at the tour. They will present information from this year's fungicide trials and also will discuss alfatoxin and other mycotoxin concerns in corn. Mike Duffy, ISU Economist, will compare the economics of continuous versus rotated corn. Also featured will be Jim Jensen, on Low Sat And Low Lin Soybean Opportunities, and Kevin VanDee on Strip Intercropping.