Monitoring of second-crop corn production areas indicates that despite the high infestation of the corn leafhopper (Dalbulus maidis), the result for the presence of stunting on the leaves was considered low. This is because, laboratory analyzes requested by the Rio Verde Technological Research and Development Foundation (Fundação Rio Verde) in the 2021/2022 harvest did not identify insects with the virus and bacteria that cause the disease in corn. However, the high population of the leafhopper is worrying and will be monitored by the entity.
The study was carried out in partnership with the Association of Soy and Corn Producers of the State of Mato Grosso (Aprosoja-MT) and the Union of Rural Producers of Lucas do Rio Verde. The objective was to obtain results on the leafhopper population in corn crops in the municipality of Lucas do Rio Verde, Mato Grosso, aiming to understand the population dynamics of the pest in the region, and thus be able to outline the best strategies to mitigate the damage caused by the pest.
Researchers from the Rio Verde Foundation analyzed three samples in each of the twelve monitored areas, from the moment the insect traps were installed, 30 and 60 days after installation. According to the reports, the percentage of leafhoppers that contain viruses and bacteria from the stunting complex was equal to zero in all samples.
Technical Responsible for the Entomology sector at the Rio Verde Foundation, Agricultural Engineer Sâmilla Emily de Oliveira Gouveia explains that in addition, samples of leaves with symptoms of stunting were sent to check whether there were already plants with the disease in the monitored areas.
"Through laboratory analyses, we identified that of the twelve areas monitored, five tested positive for the presence of at least one stunt complex disease. However, even with these positive results, we verified that the incidence, that is, the The percentage of plants that showed these symptoms was equal to or less than 5%, and in many cases it was necessary for us to enter the middle of the plot to be able to find a plant with the symptoms”, said the researcher.
Although the low infection rate of the corn leafhopper is a good result, the population was considered high and this could cause future problems for the producer.
Among insect control measures, greater attention must be paid when choosing the hybrid for sowing. Some tend to have the greatest cost-benefit due to the issue of tolerance of the stunting complex.
By controlling chemical insecticides and biological agents, it is also possible to reduce the leafhopper population to acceptable levels.
"In addition, attention must be paid to the sensitivity of hybrids to the issue of the stunting complex, as when sowing a more sensitive hybrid at the end of planting there is a greater probability of stunting occurring due to the fact that leafhoppers migrate from older plants for younger plants. In other words, the leafhoppers that are present in plants that were sown when planting began tend to migrate to areas where corn was sown when planting closed", Sâmilla pointed out.
The Rio Verde Foundation reinforces that it will carry out continuous monitoring and studies on management practices and product efficiency, to guide producers on how to live with the corn leafhopper in their crops.
"We must understand that a year's research does not provide a complete picture of the leafhopper issue in the region and the damage it causes, which is why it is so important to invest in this type of research so that we can understand the evolution or population reduction and the damage that the leafhopper is causing to the transmission of the stunting complex in corn crops", warned the researcher.
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