By The Ranch News Team
COLUMBIA, Mo. — University of Missouri Extension specialists are encouraging corn growers to begin scouting fields after corn leafhoppers were discovered in Boone County several weeks earlier than they were last year.
The insects were identified during routine field monitoring on June 16 and again on June 22 by MU Extension state row crop entomologist Ivair Valmorbida. The leafhoppers were collected from corn at the V5 growth stage, but no immature insects were found, indicating the adults likely migrated into Missouri from the southern United States rather than developing locally.
This marks Missouri’s first corn leafhopper detection of the 2026 growing season and comes roughly three weeks ahead of the state’s initial discovery in 2025. Similar early detections have also been reported this year in Oklahoma.
While researchers have not confirmed whether the insects found in Missouri are carrying corn stunt pathogens, growers are being urged to remain cautious. Corn stunt disease has already been detected in Missouri during the past two growing seasons, and infected leafhoppers have the potential to spread the disease as they feed.
Studies from South America, where corn leafhopper pressure is much greater, have shown that infections occurring early in the growing season can significantly reduce yields because plants have more time to develop disease symptoms before harvest.
Extension specialists recommend producers begin scouting fields, particularly corn that has not yet reached the R1 reproductive stage. Because corn leafhopper populations can be low and difficult to spot, visual inspections alone may not be enough. Sweep nets or battery powered vacuums fitted with collection stockings can improve detection, especially when sampling both field edges and interior rows. During vegetative growth, insects are often hidden deep inside the corn whorl.
Growers should also be aware that another insect, the aster leafhopper, is commonly found in Missouri cornfields. Although it resembles the corn leafhopper, the aster leafhopper is not known to transmit corn stunt pathogens. The corn leafhopper can be identified by two dark spots between its eyes that are surrounded by pale halos and by its lack of additional facial markings.
At this time, there is no established economic threshold in the United States for treating corn leafhopper infestations. However, Extension specialists say insecticide applications may be considered when the insects are detected before corn reaches the R1 growth stage. Producers are encouraged to choose products that minimize impacts on beneficial insects and always follow label directions.
With the earlier arrival of corn leafhoppers this season, regular scouting will be important to detect infestations early and reduce the potential risk of corn stunt disease affecting Missouri corn production.