Late-season corn diseases are starting to creep into Iowa’s corn fields, potentially causing harvest problems as stalks weaken during the final stages of plant maturation.

“With some of the wet weather we’ve been having, the diseases are starting to come on,” said Jim McDermott, DEKALB Asgrow technical agronomist based in Spencer. Goss’ wilt, northern corn leaf blight and anthracnose stalk rot are the main diseases he’s seen in northwest Iowa. In southern Iowa, reports of gray leaf spot began...