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The Corn Disease Network is a collaborative effort between Kansas Corn and Kansas State University Plant Pathology team led by Dr. Rodrigo Onofre to provide Kansas corn farmers with new tools to guard again corn diseases. For the 2026 growing season, there are 35 corn leaf hopper trapping sites located across the state monitoring for the presence of corn leaf hoppers. The network is also actively monitoring for tar spot and southern rust. Weather conditions, crop development, and disease movement can change rapidly throughout the season, making early detection and awareness critical. Farmers are encouraged to check the interactive disease maps on this webpage regularly for the latest reports, scouting updates, management recommendations and educational resources.
Our monitoring program continues its work, tracking corn leafhoppers and corn stunt as well as southern rust and tar spot. Check back often to get regular updates from Rodrigo Onofre and his team at K-State Plant Pathology. Have a corn disease concern or question? Contact Dr. Onofre directly at 785-477-0171 or by email.
It’s never too late to scout for tar spot — just this week, tar spot was reported in four Kansas counties. Three of these counties have not ever seen tar spot in past years.
Southern corn rust remains active in Kansas, with trace-levels now confirmed in several new counties across the state.
Over the past week, the corn leafhopper was detected in Lyon county, along with Labette and Barber counties. Corn is susceptible to corn stunt through the R1 growth stage.
Click on the links to see the current maps!
Click on the link to see the current map. Map will update as additional locations are reported.
Learn the best way to scout your fields for corn leafhoppers with K-State’s Dr. Rodrigo Onofre.
You’ve found some leafhoppers in your field. Dr. Onofre explains the next steps.
Can corn stunt carry over in crop residue? Dr. Onofre explains why not.
Dr. Onofre explains that not all purple leaves indicate corn stunt.
Dr. Onofre explains other plant issues that may look like corn stunt.
Dr. Onofre discusses the statewide trapping network used to detect leafhoppers in Kansas.
Learn why K-State, Kansas Corn and others are taking a proactive approach to corn leafhoppers.
Tar spot has been confirmed in 12 Kansas counties in 2026, with Clay county being confirmed Aug. 3, and Cloud county July 31.
Aug. 5 — Over the past week, the corn leafhopper was detected in Labette and Barber counties. Overall, the corn leafhopper population remains at low levels and intensifying scouting efforts is encouraged.
Aug. 5 — Southern corn rust remains active in Kansas, with trace-levels now confirmed in several counties in the eastern and central part of the state. The disease is progressing more slowly than is typical.
Southern corn rust continues to spread and has been detected at trace levels in several Kansas counties. In previous years, southern rust was typically detected by early July, and by this point in the growing season, higher disease levels would generally have been reported across the state. However, the 2026 southern rust season has progressed more slowly, with disease incidence remaining lower than is typical.
Corn leafhoppers have been confirmed in Barton, Barber, Pawnee, Reno, Rice and Stafford counties in July. KSU plant pathologist Dr Rodrigo Onofre suggests increasing your scouting efforts, especially in corn that has not reached the VT/R1 stage. Check back often for live updates to the map below and updates from Dr. Onofre.
Ten northeast Kansas counties have confirmed tar spot in the last month, with Smith confirming this week on 7/21/26. Check the tar spot map for live updates & contact Dr. Onofre with questions on treatment.
Southern corn rust has been detected at trace levels in Stafford County, Kansas week of 7/21/26. Late planted corn in central and western Kansas remains at higher risk of disease infection and should be monitored closely for disease development.
As of June 2026, corn leafhopper has been confirmed in Texas and Oklahoma. To date, neither corn leafhopper or CSS has been detected in Kansas. However, now is the time to intensify our scouting efforts. Early detection of corn leafhoppers is a vital component of corn stunt management.
Cases of tar spot have been found in Brown, Republic and Washington counties, as of June 19, 2026. Farmers are encouraged to increase scouting efforts as the corn growing season continues. The photo taken in Republic County.
2025 Corn Leafhopper-Corn Stunt Summary
11-21-25: Corn leafhopper presence was confirmed in 31 Kansas counties: Barber, Barton, Cherokee, Edwards, Franklin, Graham, Gray, Haskell, Jackson, Labette, Lane, Lyon, Marshall, McPherson, Pottawatomie, Pratt, Reno, Republic, Rice, Saline, Sedgwick, Seward, Shawnee, Sheridan, Smith, Stafford, Stanton, Stevens, Sumner, Thomas, Washington.
Corn stunt spiroplasma was detected in 25 Kansas counties: CLH: Barber, Barton, Cherokee, Franklin, Graham, Gray, Jackson, Labette, Lane, McPherson, Pratt, Sedgwick, Seward, Shawnee, Sheridan, Smith, Stanton, Stevens, Thomas, Washington. CLH & Tissue: Stafford, Saline. Tissue: Edwards, Pawnee, Riley.
The 2025 Kansas Corn Disease Management booklet has been published by Kansas Corn and K-State Plant Pathology, and is ready for download!
Corn leafhopper and Corn Stunt Updates
Corn leafhopper detections continued to increase in Kansas in September. Corn leafhoppers have been found in 30 Kansas counties. Corn stunt spiroplasma has been found in 19 Kansas counties.
K-State Plant Pathology confirmed Corn Stunt Spiroplasma (CSS) in corn plants in Stafford & Edwards Counties. Corn leaves and stalks tested positive for CSS. These plant materials were the first cases of CSS confirmed in Kansas. On August 8, KSU had a positive test of a corn leaf hopper carrying CSS in Saline County.
Corn leafhoppers have now been confirmed in 14 Kansas counties. This week, corn leafhoppers were confirmed in Washington, Stevens, Pottawatomie, Saline, Pratt, Rice, and Barton counties. Corn stunt spiroplasma presence was detected in the corn leafhopper tested from Saline County. This is the first leafhopper that has tested positive for corn stunt spiroplasma in the Kansas program this year.
Corn leafhopper, Corn Stunt, and Southern Rust Updates
Corn leafhoppers were identified in Stafford, Barber, Labette and Sedgwick counties this week; however, the leafhoppers that were tested did not carry the corn stunt disease.
Corn growers in several southwest Kansas counties should watch for southern rust reported this week in Gray, Haskell, Meade and Stevens counties.
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Because early detection of corn leafhoppers is vital to avoiding corn stunt, a monitoring system and webpage have been created to help growers track corn diseases, thanks to a collaborative effort between the Kansas Corn Commission, Kansas Independent Crop Consultants, K-State Research, Extension Ag Agents, and Corteva. Mapping of the movement of the corn leafhopper is key.
Controlling corn stunt starts with mitigating the number of corn leafhoppers in a field. Because the disease, carried by corn leafhoppers, is a bacterial pathogen, fungicides are ineffective as a treatment.
In addition to the creation of a statewide system to track leafhopper infestations, K-State Plant Pathology offers free testing to identify corn leafhoppers and plant tissue testing for corn stunt disease, thanks to support from the Kansas Corn Commission.
Contact Rodrigo Onofre, Ph.D., Assistant Professor, Extension Specialist, Row Crops Pathologist at the K-State Plant Pathology Department.
