While the Iowa corn crop may appear good from the highway, looks may be deceiving. The heat is taking its toll and yield is likely to be affected, according to the Des Moines Register. The hottest July since 1955 has been recorded in the state and Iowa's corn crop may pay the price.

The USDA in mid-July forecast this year's national corn yield at 158 bushels per acre. However, Iowa State University meteorologist Ellwyn Taylor is not quite as optimistic. Taylor said Monday that "with heat and humidity, the U.S. corn yield is likely to be about like last year, at 153 bushels per acre."

The oppressive heat hanging over the Midwest for the past couple weeks is taking its toll in the form of reducing kernel fill on corn plants as well as disease.

Roger Elmore, Iowa State University agronomist, said warm nights have reduced the kernel size in the ears and led to more disease problems in Iowa's corn, particularly Goss's wilt and gray leaf spot.

The condition of the nation’s corn crop remained steady last week, according to the most recent USDA Crop report, with 62% of acres rated in good or excellent condition. The report seemingly defied expectations. “Looking at the state level data, it is difficult to see how the national ratings held steady,” according to authors of the CME Daily Livestock Report. “Good to excellent ratings in Iowa, Illinois and Indiana fell by 5.6% and 5%, respectively, while those for Nebraska and South Dakota fell by 3%.”

This week’s good to excellent percentage is almost precisely equal to the average of the past 10 years for this week, however questions remain on the outlook. “Several lower-acreage states saw good or excellent ratings increase but how they could overcome significant declines in the large corn states is a bit baffling,” say the Daily Livestock Report authors.

"There is reason to be concerned," Elmore said of this year's crop.

Source: Des Moines Register, CME Daily Livestock Report