Corn leafhopper (CLH; Dalbulus maidis), the vector of corn stunt disease complex, was confirmed in Reno County, Kansas, on July 9, 2025 (Figure 1). Corn leafhoppers have been detected in 38 counties in Texas, 3 counties in Oklahoma, and 1 county in Missouri. Now is the time to intensify scouting efforts.
The early insect onset we’re observing this year raises concerns about yield loss. Late-planted corn and/or double-cropped corn are at a higher risk of yield impact than early-planted corn. Corn stunt disease symptoms can take up to 40 days for symptoms to become visible. Due to the efficiency of the corn leafhopper to transmit pathogens associated with corn stunt disease, there is no economic threshold.
At this time, the exact corn growth stage at which scouting should cease is unknown. Past guidance encouraged scouting through V8, but more studies are needed to verify the validity of this recommendation. Insecticide applications are an option when corn leafhoppers are detected. Broad-spectrum insecticides are suggested as the best option for CLH control; however, insecticides might not be a bulletproof option to prevent corn stunt disease due to the occurrence of multiple waves of CLH that may occur throughout the early growth stages. Keep in mind that spraying for CLH could increase the chances of spider mite infestations. In addition, corn stunt disease incidence will not be reduced by insecticide or fungicide applications. If symptomatic corn plants are observed in the field, the plants have already been infected. Remember, the label is the law.
Figure 1. Corn leafhopper (Dalbulus maidis) in Kansas in 2025. The map can be accessed at https://kscorn.com/corndisease/
Identification of the corn leafhopper
The corn leafhopper is relatively simple to identify under magnification (Figure 2). These leafhoppers are light tan to yellowish-white in color and approximately 1/8” long. Two distinct dark spots between the antennae and eyes are very characteristic of this species. Nymphs lack wings and can vary in color.
Like most leafhoppers, all stages move quickly when disturbed and hide in shaded areas of corn plants. All stages can be sampled using a sweep net. A video showing how to sample/trap corn leafhoppers in mature corn canopies can be found here: https://youtu.be/QgLuWWSwHWU. It is important to know that not all leafhoppers found in corn fields will be corn leafhoppers. A commonly found species, the aster leafhopper, can be confused with the corn leafhopper (Figure 2, right).
Figure 2. Images of the corn leafhopper (left) and the aster leafhopper (right). Photos courtesy of Rodrigo Onofre, K-State Research and Extension.
Corn stunt spiroplasma (CSS, Spiroplasma kunkelii) and its associated vector (corn leafhopper, Dalbulus maidis) were first confirmed in Kansas during the 2024 corn season. Although most of the positive reports were from field corn, we also confirmed CSS in sweet corn. High levels of disease were found in late-planted and double-cropped corn, leading to potential yield reductions. Corn leafhopper acquires pathogens within minutes of feeding on infected corn plants, but it can take up to 40 days for the leafhopper to be able to infect healthy corn plants during feeding events. The corn leafhopper can also transmit additional pathogens, either singly or in combination with CSS. To date, only the CSS pathogen has been confirmed in Kansas.
Please help us track! K-State is offering FREE TESTING for corn leafhopper identification and corn stunt disease.
Kansas corn farmers have new tools to guard against corn leafhoppers and corn stunt disease. The Kansas Corn Commission is supporting the work of K-State Plant Pathologist Rodrigo Onofre to track leafhoppers and corn stunt disease in Kansas to help growers manage this risk. In addition to the creation of a statewide system to track leafhopper infestations, K-State Plant Pathology is offering FREE TESTING to identify corn leaf hoppers (CLH Confirmation and Pathogen Presence) and plant tissue testing for corn stunt disease, thanks to support from the Kansas Corn Commission. Collection and shipping instructions can be found below:
- Collect and ship samples on or before Wednesday to avoid weekend storage
- Collect symptomatic fresh leaf tissue.
- Use a sweep net to collect insects. Empty net into gallon plastic bags.
- Label and use plastic bags; Do not use paper bags, and do not add water.
- Fill out the submission form. Please make sure to add a “2025 FREE CORN STUNT TESTING” note to the submission form.
- Ship samples ASAP overnight via UPS or FedEx if possible.
K-State Plant Diagnostic Lab
4032 Throckmorton PSC
1712 Clafin Road
Manhattan, KS 66506
K-Trap Monitoring System
Early detection of corn leafhoppers is a vital component of corn stunt management. To help communicate monitoring results in real-time, a monitoring system and webpage have been created to help growers track corn leaf hopper, corn stunt, and other corn diseases (kscorn.com/corndisease). A collaborative effort between K-State Plant Pathology, Agronomy, and Entomology departments, the Kansas Corn Commission, Kansas Independent Crop Consultants, K-State Research & Extension Ag Agents, and Corteva has been initiated to monitor at least three counties in each crop reporting district for corn leafhoppers (Figure 3).
Figure 3. In-season K-Trap monitoring. Counties that are blue have at least one trap for CLH that is monitored weekly during the 2025 corn season.
Approximately 33 Kansas participants are trapping for the corn leafhopper. Monitoring is ongoing and will continue for 40 weeks. This will help us understand the real-time risk during the growing season. The leafhoppers that are trapped will be tested to see if they carry the pathogens that cause corn stunt disease. Any detections will be added to a map that tracks corn leafhopper detections in Kansas and other states (kscorn.com/corndisease). This page also includes maps for corn stunt pathogens, tar spot, and southern rust, as well as video updates from K-State Research and Extension.
For more information, contact Rodrigo Onofre, Assistant Professor and Extension Specialist, Row Crops Pathologist at the K-State Plant Pathology Department. E-mail: onofre@ksu.edu or at 785-477-0171.
Check out these short videos for answers to some common questions about corn stunt and leafhoppers
Learn the best way to scout your fields for corn leafhopper
www.youtube.com/shorts/_n7RZq0ougY
What next?
www.youtube.com/shorts/-PzNFirAGY0
Does corn stunt carry over in corn residue?
www.youtube.com/shorts/5rUZdi4CG3Q
Purple corn leaves – Is it corn stunt?
www.youtube.com/shorts/Jxkicq8DQfA
What other problems look like corn stunt?
www.youtube.com/shorts/dtjD8Wpip6A
How are sticky traps used to track corn leafhoppers?
www.youtube.com/shorts/DqLKsUI2xcs
Leafhopper project: What, Who, and Why?
www.youtube.com/shorts/XPEnmN05Nfc
Rodrigo Onofre, Row Crop Plant Pathologist
onofre@ksu.edu
Anthony Zukoff, Extension Entomology
azukoff@ksu.edu
Tina Sullivan, Northeast Agronomist
tsullivan@ksu.edu