The corn leafhopper (Dalbulus maidis), widely regarded as the most important pest affecting maize, has caused billions of dollars in losses to Brazilian production. A new study has now quantified the economic impact of corn stunt diseases in the country, showing that between 2020 and 2024 Brazil lost, on average, 22.7% of its maize yield to these diseases, whose pathogens are spread by the insect vector. This translated into annual losses of around US$6.5 billion.
Across the four crop seasons covered by the study, cumulative losses reached US$25.8 billion, with an estimated 2 billion 60-kilogram bags of maize never produced.
The results are based on an analysis of National Supply Company (Conab) data, including historical series on yield, grain production and planted maize area dating back to 1976. Using these data, the researchers estimated the economic losses associated with crop damage in Brazil’s main maize-producing regions, according to a press release.
Published in the international journal Crop Protection, the study shows how corn stunt diseases and the corn leafhopper have developed from a relatively minor concern into one of the most serious challenges facing Brazilian maize production in recent decades. The research was carried out by Embrapa Cerrados, the Agricultural Research and Rural Extension Company of Santa Catarina (Epagri), and the Brazilian Confederation of Agriculture and Livestock (CNA).
An overview of the losses
Alongside statistical data, the researchers also used information gathered through the Campo Futuro project, an initiative of CNA and the National Rural Learning Service (Senar). Surveys were conducted in 34 municipalities representing Brazil’s main producing regions, with input from farmers and technical experts. Based on this technical consensus, the team identified and estimated the losses linked to the corn leafhopper and the corn stunt disease complex in each municipality and crop season.
The greatest impact was recorded in the 2020/2021 crop season, when production losses reached 28.9%. By the 2023/2024 season, that figure had fallen to 16.7%. Over the same period, spending on insecticides to control leafhoppers increased by 19%, rising to more than US$9 per hectare and significantly adding to farmers’ production costs.
“The results indicate that corn stunt diseases led to an average loss of 31.8 million tons per year,” Charles Oliveira, a researcher at Embrapa Cerrados and author of the study, points out. In about 80% of the locations surveyed, leafhoppers or leaf damage were identified as the main factor behind the decline in yield.
Larissa Mouro, coordinator of Campo Futuro, emphasizes the importance of the study for the production sector: “The data have made it possible to generate a consistent economic estimate covering the entire country.”
The threat of stunt diseases
Brazil is the world’s third-largest maize producer and one of its leading exporters. According to Conab, the 2025/2026 crop is forecast to reach 138.4 million tonnes, with an estimated production value of around US$30 billion.
At present, two forms of corn stunt disease, pale stunt caused by Spiroplasma kunkelii and red stunt caused by “Candidatus” Phytoplasma asteris, represent the most serious phytosanitary threat to Brazilian maize production. Both are spread by the corn leafhopper, which is also known to transmit corn streak mosaic virus and maize rayado fino virus.
According to Embrapa researchers, the threat is made more severe by the absence of effective preventive treatments for these diseases. In fields planted with susceptible hybrids, infections can lead to total crop loss.
Although the pathogens have been known since the 1970s, outbreaks have become increasingly frequent since 2015.
“Changes in the production system over the past few decades, such as the expansion of double cropping and the cultivation of corn throughout most of the year, have created favorable conditions for the survival of leafhoppers and microorganisms,” Oliveira explains.
According to Tiago Pereira, a technical advisor at CNA, the leafhopper is no longer a localized problem: “We’re talking about losses that directly impact farmers’ incomes, production stability, and the country’s competitiveness. What sets this study apart is that it translates this recurring perception into scientifically grounded data.”
