This information was summarized from a May 20 teleconference with Iowa State University extension field specialists in crops.
- Corn emergence has been slowed by cool temperatures. Some scattered rain and frost were reported. Postemergence herbicides are being applied in some areas, but in others are being delayed because of cool temperatures. Corn growth stages that were reported are listed in the table. (When corn is emerging, the stage is VE. As leaf collars are visible the "E" is replaced by a number, such as V1, which refers to 1 leaf collar that is fully visible.)
- Estimated soybean planting ranges from 30 to 98 percent statewide. Emergence is slow in some areas, but approximately 50 percent of seedlings have emerged. Bean leaf beetles are a concern, but few fields have warranted treatment (see article on pages 81-82).
- Several specialists reported cornfields with poor germination and emergence problems, including plants that are leafing out underground. A few very early-planted fields have been replanted in the northwest. Some fields that have frost and wind damage may be confused with cutworm damage. A few fields have been sprayed for black cutworm. Scattered reports of wireworm and true white grub problems continue.
- Alfalfa fields look good in most areas and first cut has started in southern and central Iowa. Alfalfa aphids have been reported above the threshold in some fields in the northwestern and central Iowa areas. Most of these fields are second year alfalfa and there are circular areas of the fields affected. In northwestern Iowa, some of the populations dropped dramatically within a few days.
This article originally appeared on pages 86-87 of the IC-488(10) -- May 27, 2002 issue.