How To Wrestle 2020 Corn Diseases

By: Gil Gullickson

Corn farmers wrestled with old and new corn diseases in 2019 that likely will again be present in 2020.

These included the usual suspects, such as gray leaf spot. One new one, though, is Physoderma brown spot. Symptoms of this fungal disease include numerous lesions that appear on midcanopy leaves. Nodal infection from this disease can cause stalk rot to occur. The good news is that after this spring’s prolific rainfall, dry weather curbed disease development.

“Some diseases like southern rust appeared early, but dryness inhibited development,” says Randy Myers, Bayer Crop Science fungicide product development manager. “Last year, gray leaf spot around the Midwest was the worst I have ever seen. This year, it could be found everywhere around the Midwest, but it did not progress as rapidly due to dry conditions.”

However, wet weather has caused some diseases to pick up. Myers says a Bayer field trial check in late August indicated no or little signs of southern rust. Several days later, it scattered all over the field.