Judging crops at the Morgan County fair last week, I expected to see lots of disease lesions, particularly gray leaf spot and northern corn leaf blight, coming in on corn. Granted, 4-H members and their parents try to pick stalks that have as few brown spots as possible, but with the humidity levels we have experienced, I thought that come would have a hard time finding plants without at least some lesions.
As it turns out, I was wrong. Maybe 10% of the plants had lesions, and only one of them had a lesion above the ear leaf, and it was small. It was difficult finding a lesion to show the 4-H member what to look for, because they just weren't there.
My observations match up with those Dave Nanda, director of genetics and technology for Seed Consultants, Inc. He's been traveling the eastern Corn Belt recently, and he's seen only a small amount of foliar disease showing up so far. Better plant resistance to the diseases may explain part of it, but he thinks there is a bigger reason.
"It's been humid, but it's also been very hot," he said. Indeed, The National Weather Service at Indianapolis called July the second hottest July on record, and the streak of 90 degree or higher days in central Indiana was past 15 at last count.
"We've not had a lot of moisture," he notes. My Rain Scout, a service offered through Beck's Hybrids, Atlanta, Ind., confirms about 1.2 inches of rain near Franklin and 0.65 near Morgantown for the entire month of July. The service at two sites with daily and monthly reports to Indiana Prairie Farmer is courtesy of Beck's Hybrids.
"The diseases need more than humidity to flourish," Nanda says. "They also need moisture. We just haven't had it. It's not been good for the plants, but it's not been good for these corn fungal diseases either."
Nanda is cautious, knowing the situation could change if the pattern switches to cooler and wetter weather before the season is over. If that happens, more disease could develop, particularly in fields not sprayed with fungicides with preventive activity.For the moment, however, it's not been a good summer for foliar corn diseases either. Time will tell how the rest of the season progresses, and whether foliar diseases play a role in drydown and set plants up for stalk rots.