It could be spider mites!
Colonies of spider mites feed on the undersides of corn leaves starting from the bottom of the plant. You’ll first notice them on the edges of your fields. Spider mite feeding can result in yellow leaves, with a scorched or burned appearance, as in the photo below. This past month’s hot, dry weather created the perfect environment for spider mites. They are a particular problem in drought-stressed corn. In a typical year here in Upstate NY, we get enough moisture to prevent outbreaks – wet leaves and a naturally occurring fungus keep populations in check. But this year they are out there!
Should you do anything about spider mites? Well, it depends…
Scouting strategies and treatment options are described in this article, Two-spotted spider mite management in soybean and corn, from University of Wisconsin Extension. Call us if you are concerned about spider mites in your corn or soybeans and would like guidance on whether to treat for them.