Drought stress in corn continues

This information was summarized from a July 1 teleconference with Iowa State University extension field specialists in crops.

  • Some areas have been without rainfall for a month and the corn stays rolled most of the day. The driest areas are in the western third of the state. The biggest concern is that corn is in a critical time of development and more moisture is needed.
  • Corn is typically at the V12 to V14 growth stage. Stress-induced potassium deficiency symptoms continue. Crown rot has been observed in some fields. Mark Carlton (southeast) reported some rootless corn, especially in fields planted around May 20. Corn rootworm larvae are appearing on the roots in some fields. Very few first-generation European corn borer were evident.
  • Soybean growth stage is mainly V4 to R1. Soybean aphids have been reported in Winneshiek, Floyd, Buena Vista, and Woodbury counties and a few other scattered locations. Populations are fairly low. Grasshopper nymphs in grassy areas and field edges were reported. Drift calls continue, but much of the soybean spraying is complete. Iron chlorosis, soybean cyst nematode, and root rot are still prevalent in some fields. In the drier areas, soybean plants are shorter than normal.
  • Second-cut harvest of alfalfa is about half done. Potato leafhopper numbers are heavy in some areas and are being sprayed. More pastures are reported to be very dry and going dormant.
  • Oat crop generally looks good, it is beginning to ripen, and disease symptoms are showing up in some fields.

This article originally appeared on page 139 of the IC-488(16) -- July 8, 2002 issue.

Updated 07/07/2002 - 1:00pm