End of August Crop Update for Northwest Iowa

August 28, 2019 3:06 PM
Blog Post

Check out what ISU Extension and Outreach field agronomists in NW Iowa are seeing and hearing in their areas regarding crop progress and issues showing up in crop fields.

Joel DeJong (Cherokee, Ida, Lyon, Monona, O'Brien, Osceola, Plymouth, Sioux, and Woodbury Counties ): “In the NW corner of Iowa, most of the counties received a nice rain in the last two weeks. Lighter soils still show some stress, but most acres look good from the road at least. In the field, the crops look pretty good, too, except many aren’t nearly as mature as I would like of see for the last week of August. The June planted corn I observed late last week was still in the milk stage. There is a lot of concern about not only an early frost, but even some concern about a normal frost for corn along the Minnesota border with the present cooler than normal forecast. In most years, silage chopping has started by now. I have seen no activity so far this year. I have seen some disease pressure, but it doesn’t appear to be widespread in the region. Soybeans are starting to fill pods, and the southern part of the area has reported scattered patches of white mold this past week. Soybean aphids have reached treatment thresholds in scattered locations, too. Overall, this corner of the state looks quite good, except for the stage of growth for the last week of August.”

Paul Kassel (Buena Vista, Clay, Dickinson, Emmet, Hancock, Kossuth, Palo Alto, Pocahontas, Sac, and Winnebago Counties): “Soybean aphids have been the question of the week. Aphid numbers have continued to increase during August. Farmers are encouraged to make random checks throughout the field for soybean aphids and use the 250 aphid/plant threshold on 80% of the plants. Usually treatment is not beneficial after the R6 stage (soybean fills the pod cavity at one of the top four nodes) of development. A third generation of thistle caterpillars can be find in some soybean fields as well. The early May planted corn is in the hard dent stage and could be expected to reach the black layer stage of development in about three weeks.  June planted corn is in the late milk/early dough stage and could be mature in about five weeks.”   

A third generation thistle caterpillar found in a Buena Vista County soybean field. Photo courtesy of Paul Kassel.

Find your local ISU Extension and Outreach field agronomist here!