Corn Leafhopper Confirmed in Eastern Kansas - No Corn Stunt Spiroplasma Detected to Date

Over the past week, the corn leafhopper (CLH; Dalbulus maidis), the vector of the corn stunt disease complex, has now been detected in Labette and Barber counties, KS (Figure 1). All the CLHs were negative for Corn stunt spiroplasma (CSS, Spiroplasma kunkelii). Overall, the CLH population remains at low levels, and we encourage intensifying scouting efforts. Learn the best way to scout your fields for corn leafhopper here: www.youtube.com/shorts/_n7RZq0ougY.

Figure 1. Corn leafhopper (Dalbulus maidis) in Kansas in 2026. The map can be accessed at https://kscorn.com/corndisease/.

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 may take up to 40 days 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. We encourage scouting through VT/R1, but more studies are needed to verify the validity of this recommendation.

Insecticide applications are an option. However, trials conducted in 2025 in Oklahoma and Texas found that broad spectrum insecticides were largely ineffective against corn leafhoppers. Up to 14 days of nymph suppression was observed with applications of indoxacarb, flupyradifurone, and thiamethoxam+lambda-cyhalothrin. However, insecticides are not a bulletproof option for preventing corn stunt disease, as multiple waves of adult CLH may occur throughout the season. Note that insecticide applications with lambda-cyhalothrin may increase the risk 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.

Identifying the Corn Leafhopper

The corn leafhopper is relatively simple to identify under magnification (Figure 2a-b). 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 2c-d).

Figure 2. Images of leafhopper: A) Above view of the Corn Leafhopper showing the two black spots surrounded by light/white “halos” and B) Underside view of the Corn Leafhopper showing no markings on the face. C) Above view of the Aster Leafhopper showing the two black spots, no light/white “halos” are present, and D) Underside view of the Aster Leafhopper showing facial marks. Photos courtesy of Rodrigo Onofre, K-State 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, but not in 2026 as of August 3.

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:

• 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 “2026 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

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.

FAQs for Corn Leafhopper and Corn Stunt

Learn the best way to scout your fields for corn leafhopper: https://www.youtube.com/shorts/_n7RZq0ougY

Does corn stunt carry over in corn residue: https://www.youtube.com/shorts/5rUZdi4CG3Q

Purple corn leaves – Is it corn stunt: https://www.youtube.com/shorts/Jxkicq8DQfA

What other problems look like corn stunt: https://www.youtube.com/shorts/dtjD8Wpip6A

How are sticky traps used to track corn leafhoppers: https://www.youtube.com/shorts/DqLKsUI2xcs

Leafhopper project: What, Who, and Why: https://www.youtube.com/shorts/XPEnmN05Nfc

For more information, please visit https://kscorn.com/corndisease/

 

Rodrigo Onofre, Row Crop Plant Pathologist
onofre@ksu.edu

Anthony Zukoff, Extension Entomology
azukoff@ksu.edu