Tiny Insect, Big Problem: OSU faculty continue monitoring the Corn Leafhopper in Oklahoma through Research and Extension
Friday, December 19, 2025
Media Contact: Sophia Fahleson | Digital Communications Specialist | 405-744-7063 | sophia.fahleson@okstate.edu
Cornfields across Oklahoma are under close observation as the corn leafhopper makes its tiny but mighty presence known. While only the size of a grain of rice, this invasive insect is causing big problems for corn producers statewide.
Faculty at Oklahoma State University and OSU Extension are working together to identify the corn leafhopper, the pathogens it spreads, and ways producers can manage and monitor the issue.
Oklahoma cornfields infected by the leafhopper in 2024 took a major hit with 10-55% yield loss, said Ashleigh Faris, OSU Extension cropping systems entomologist and integrated pest management coordinator.
“There was documentation of the disease from the 1940s in south Texas with reoccurrences in other states,” Faris said. “It likely has been in Oklahoma prior to 2024, but no one knew what it was, or what to look for.”
Identifying symptoms of corn stunt disease are often similar to those of nutrient deficiencies, with stunted growth and yellow to red leaf streaking, said Estefania Jinez-Rodriguez, a visiting scholar from Ecuador and OSU entomology and plant pathology intern in the plant pathology Extension lab.
Knowing the identifying symptoms is half of the problem to look for. If these symptoms are noticeable, producers should check for leafhoppers, Jinez-Rodriguez said. Together, the likelihood for corn stunt disease, caused by the corn leafhopper, increases significantly.
Corn stunt disease does not kill the plant. Instead, the pathogen absorbs the nutrients the plant needs to grow, Jinez-Rodriguez said. In response, the plant becomes stunted, produces multiple ears and takes on a sickly appearance as it struggles to fight the infection, she said.
“The hopper is small in size, yellow to tan in color and has two dark dots located in-between its eyes,” Faris said. “However, those dots are the same as a lot of other leafhoppers, making field identifications difficult – often resulting in misidentifications.”
In Oklahoma, corn is typically not as intensively managed as other crops, Faris said. Scouting cornfields is a quick way for producers to check if the pest is present. Ways to scout include walking the outer rows of cornfields and checking around the leaves of the plant for present corn leafhoppers, she said.
“Just because you have the insect, doesn’t mean you are always going to have the pathogen the insect is transmitting,” Faris said. “The insect has to pick up the pathogen from somewhere else. Plus, they don’t pass pathogens along to their babies.
“Each leafhopper has to pick it up from the environment,” she added. “So, if you have a low pathogen year, even if you have a high population of leafhoppers, there’s not as much opportunity to pick up that pathogen.”
To know if the leafhopper is a carrier of the pathogens, it must be tested. Part of OSU Extension’s role in research includes sending in insect and corn samples for identification and testing of diseases through the Plant Disease and Insect Diagnostic Laboratory, or PDIDL.
When testing the corn leafhopper in the PDIDL, the insects' legs must be carefully removed from its body and tested independently, said Sara Wallace, plant diagnostician.
“We test the body for identification,” Wallace said. “We want to verify it is the corn leafhopper since there are so many different types of leafhoppers. The legs are tested to see if the insect is transmitting the pathogen.”
Due to the corn leafhoppers' small size, producers can use sticky traps to collect insects for testing. For proper implementation, producers can place traps along the outer rows of the field on posts at canopy height.
“Producers this year have been scouting fields more intensively than in previous years,” said Isaac Peebles, Golden Harvest Seeds Oklahoma territory manager. “Using sticky traps and knowing where to find corn leafhoppers has made an impact on production in Oklahoma.
“With the destruction caused last year, there is a fear among producers, resulting in them being proactive and looking for the signs of corn stunt disease,” he added.
Peebles works directly with corn producers across Oklahoma and said he has assisted in scouting methods and sending in samples to the PDIDL.
The tricky part is plants often do not show symptoms of infection until 21-30 days of exposure, Faris said. Time may vary depending on the type of pathogen transmitted, she added.
“The leafhopper transmits three pathogens,” Wallace said. “There’s a virus, a phytoplasma and a spiroplasma, but the phytoplasma and the spiroplasma are what’s most common in the United States.
“When testing the plant for disease, we need symptomatic material,” she said. “That can be reddening, purpling or streaking of the leaves. Then, we cut the leaves up and perform molecular testing depending on the type of pathogen we are testing for.”
For testing, a positive control of the certain pathogen is needed, Wallace said. As of today, only the cornstunt spiroplasma has been found in Oklahoma, she added.
Nothing can be done to save the plant or yield once it has become infected, Faris said. Managing becomes an important step to control the problem before it spreads.
Part of the research Faris conducts is examining weather patterns to determine influencing factors for insect population in specific years or regions.
“The possible reason why south Texas is a really big hot bed for this issue is because they have very mild winters,” Faris said. “With that, volunteer corn sprouts up after harvest. We see that in Oklahoma, too, but it is more common for producers to graze that area.
“Last year in Oklahoma we had a freeze come in mid-December and kill all the volunteer corn,” she said. “The reason this is important is because corn leafhoppers can only be produced in corn itself. If you can knock out the volunteer corn, or resources they produce on, then you’re helping to reduce that population of the insect and the reservoir for the pathogens.”
Volunteer corn refers to corn plants that grow unintentionally from kernels left in the field post-harvest. These plants often compete for nutrients, water and sunlight, potentially reducing yields for producers and creating habitats for the corn leafhoppers to thrive, Faris said.
Knowing the identifying factors of the insect and the symptoms of corn stunt in the plant itself can help producers safeguard their fields and bring awareness to the rising issue.
“This has become a top issue to look for in production when it comes to scouting and preventative measures,” Peebles said. “It is a new phenomenon in Oklahoma that impacts the corn industry, and we need to be more conscious when monitoring for the pest and symptoms.”
Story by: Annabelle Blasius | Cowboy Journal