Heat was the theme to close out August, and early September is not looking to give much relief to the end of the growing season.
Despite the dry weather, disease has been an issue for growers in southwest Iowa and northwest Missouri, according to Iowa State University Extension field specialist Aaron Saeugling in a post on the Extension blog. However, he noted that some of the reported disease damage has been misinterpreted and may be signs of late-season insect pressure.
“Dectes stem borer has been around quite a bit,” Saeugling said. “Their effects can look like diseases or other insects without looking too closely.”
The pests are just another thing to worry about after a tough year around much of the state. Northeast Iowa farmer Rick Juchems said he expects his corn crop to be in rough shape when it comes to harvest season as rainfall has been hard to come by in 2023. Much of the state is lagging behind in moisture Juchems’ farm is only at 61% of its normal moisture.
“The crop is done,” Juchems said. ”If it started raining it wouldn’t make a difference in the yield.”
That stress has crossed the Mississippi River to Illinois where University of Illinois agriculture Extension educator Russ Higgins wrote his area of northeast Illinois doesn’t expect to see late-season fill from rain.
“The opportunity for added filling of kernels experienced last year appears very unlikely as the R6 corn hastens to maturity,” Higgins said in an email to Iowa Farmer Today. “Fields with greater water holding capacity are faring much better than lighter soils, but even those are showing some remobilization of nutrients from lower leaves in the canopy for the ear.”
Saeugling said his area in southwest Iowa has received a bit more rain than average across Iowa, 85% of normal precipitation, but that has led to a few more foliar diseases.
“With heavy rainfall in most areas in late July and early August, there’s been plenty of disease,” he said. “Most notably we’ve seen white mold, sudden death syndrome, and brown stem rot in soybeans. It’s too late for fungicides, but these diseases will likely impact final yields.”
Corn has also had a fair amount of damage from pests like aphids in the northern region of Iowa, according to Iowa State Extension agronomist Josh Michel wrote in a crop update.
“Japanese beetles and grasshoppers continue to be the big ones,” Michel said.
He said silage harvest has started in the region, but the crop being harvested is showing high nitrate levels. That is often found in drought-stressed corn and increases potential for poisoning in older livestock on lower-energy rations.
“The potential for high nitrate silage can be made even worse if drought-stressed silage is harvested within 10 days of a rainfall event, since the rain increases crop uptake of soil nitrogen,” Michel said.
Despite the heat, dry weather and pressures reported by agronomists and farmers, crop conditions are holding up surprisingly well, according to the USDA.
Based on the Aug. 28 crop progress report, the national crop condition for corn was rated at 58% good-to-excellent, only losing two percentage points in the extreme heat. Iowa sits at 54% good-to-excellent, Illinois at 67% and Missouri at 41%.
Soybeans were rated at 58% good-to-excellent nationally, only a 1 point decrease during the hot week, while Iowa sits at 53%, Illinois at 68% and Missouri at 49%.