Susceptibility of corn hybrids to corn stunt complex transmitted by the corn leafhopper, Dalbulus maidis (DeLong & Wolcott, 1923) in Brazil

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Corn (Zea mays L.) production plays a key role in the global agricultural scenario. Corn is currently the most produced cereal in the world, with more than 1.1 billion tons harvested in 2021. The main pest that affects corn in Latin America is the corn leafhopper (Dalbulus maidis) (DeLong & Wolcott, 1923). This insect causes direct damage to Zea mays plants through suction of the corn sap, but its importance is greater due to the transmission of two phytopathogens of the mollicute class: the phytoplasma (MBSP – maize bushy stunt phytoplasma) that causes the red stunting; and spiroplasma (Spiroplasma kunkelii) which causes pale stunting; in addition to a virus, the corn stripe virus (MRFV – maize rayado fino virus). Stunting is a systemic disease that affects the physiology, nutrition, and development of the corn crop, significantly reducing its productivity. Therefore, the use of resistant hybrids is the main alternative to reduce the incidence and damage caused by corn stunting. This work aimed to evaluate the susceptibility of maize hybrids to the stunting complex transmitted by the corn leafhopper in three different sowing dates. The experiment was carried out with 63 corn hybrids in three different sowing times, the first being on 11/24/2022, the second on 12/30/2022 and the third on 02/06/2023. The hybrids SHSuper CONV, NTX454 VT PRO2 and FS670 PWU were the ones that had the lowest rates of stunting severity, showing a high resistance to this disease complex. The hybrids AG9025 PRO3, DKB240 PRO3 and K9300 PRO3 were the ones that presented the highest disease severity scores (6 to 5.7 on the scale used), indicating a high susceptibility to the stunt pathogens complex. The use of less susceptible hybrids is one of the main components for managing stunting diseases complex in the corn crop in South America, being one of the most important features, together with potential yield, as a parameter for growers to select the hybrid to be used.