ST. LOUIS — Some Illinois corn producers are discovering that despite how good their crop looks from the road, problems may be hidden away inside the ears.

The excessive rainfall in the spring and below-average temperatures over the summer may be responsible for yield-robbing deficiencies and plant diseases.

“We’re about 200 growing-degree days behind in some areas,” Monsanto agronomist Luke Cole said at a Channel customer meeting here. “You’re talking about a good 10 days or so to make those up. We’re seldom hitting 90 degrees this summer. Normally, we’re hitting a lot more 90-degree days and 100-degree days in the summer.”

That could mean higher drying costs following harvest, according to Cole.

“Our harvest date continues to be pushed back. It looks like we’re going to have some wet corn to deal with this fall, especially for that June-planted corn,” he said. “That was the concern: What if we have a cooler-than-average summer? And we’re starting to see that show up now.”

Lack of pollination is showing up in some fields. Many of Cole’s customers are seeing unfinished ears. Ears missing the top 10 or so rows of kernels are becoming a common site.

“We drive by on the highway and they look great and we’re feeling really good about it, saying we’re going to have 200-bushel corn,” Cole said. “But I’m getting in a lot of fields and finding 10 or more rows of kernels (missing) and streaks down the side not getting pollinated.

“Why didn’t it pollinate? I think a stack of things; obviously environmental. You’re seeing a lot of this stuff show up across all brands, across all of Illinois. We’re concerned about this. That said, I don’t believe it’s a sky-falling scenario. I’m hoping that this doesn’t show up as big as it could in the fall.”

The problems shouldn’t come as a surprise, considering the heavy rainfall that covered many parts of the state following planting, according to Cole.

“We’re quick to forget the spring we went through and the struggles some of this corn had early,” he said. “Some of these fields went through some real hard times with this moisture, and that’s what’s showing up. We had a lot of plants that were struggling to stay alive.”

The cool temperatures also have helped usher in some diseases. Agronomist Stephanie Rousoneles, who covers east-central Illinois, said gray leaf spot has been found in a number of fields.

“This is something I’ve been seeing,” she said. “Some people in southern Illinois have been seeing some, too, especially in corn-on-corn fields, but also in rotated acres. Depending on how much of this pathogen you have, a fungicide could be a good choice. It comes in at 75 to 85 degrees. We’ve been having a lot of dew in the morning.”

While common rust also is widespread, it shouldn’t cause significant problems unless it appeared early, according to Rousoneles.

In soybeans, frogeye leaf spot can be a concern, though weather conditions have not been conducive to it.

“You guys farther in the south have seen some tolerance in our Channel lineup,” Rousoneles said. “Those varieties have a lot of resistance. But also we can use a fungicide. Frogeye comes in at hot, humid conditions, which we’re not extremely hot right now. Just be scouting for that.”

Bacterial blight is another disease that can affect soybeans late in the season. And while it can result in yield losses, it usually isn’t a major problem.

“This comes in every year pretty much in soybeans,” Rousoneles said. “The only time this is a real yield robber is if you have extreme defoliation. Just pay attention. I wouldn’t be extremely worried.”