Yellow and brown leaves on the edges of your corn fields – what’s happening?

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.

Have you tried the Pioneer Seeds app?

The Pioneer Seeds app is a new tool available from Pioneer for download in the app store. With Pioneer Seeds, you can see cumulative GDU’s and 24-hour rainfall data for each of your fields. It also allows us to pinpoint field observations while scouting and send reports of any issues we find. To use it effectively, we need to get your planting data into the database that underlies the Seeds app. Talk with us if you would like to get set up for using this helpful app!

More information about what you can do with the Pioneer Seeds app is available at https://support.fields.corteva.com/hc/en-us/articles/360030661891-What-can-I-do-with-the-Pioneer-Seeds-app-.

Are flea beetles a problem?

Flea beetles like those in the photo below, spotted in a field in Tompkins County, cause only minor chewing damage to corn plants. However, they are a vector for a disease called Stewart's Wilt. Stewart's Wilt is a bacterial disease that affects field corn and sweet corn. Many hybrids are resistant, but Stewart's Wilt can be a big problem on varieties that are not. Early in the season, the disease causes systemic wilt and can result in plant death, and after tasseling it manifests as a foliar blight. The later season blight rarely results in plant death, but can predispose the plant to stalk rot.

If you see flea beetles, you can ask us about your hybrids' resistance levels. And more information about Stewart's Wilt is available from Pioneer at https://www.pioneer.com/us/agronomy/stewarts_wilt_cropfocus.html.