Avaliação de híbridos de milho quanto ao complexo enfezamento com e sem a aplicação de inseticida químico combinado a biológico

Abstract

In recent corn harvests, the southern region of Brazil has been affected by the increased incidence of the so-called stunting complex. This comprises the yellow and red stunting, and has as causal agents bacteria of the Mollicutes class, which are transmitted by the leafhopper (Dalbulus maidis). These diseases compromise the yield components and productivity of this cereal. The objective of the present study was to evaluate maize hybrids in terms of their tolerance to complex stunting without and with the application of a chemical insecticide combined with a biological one (Beauveria bassiana). The experiment was carried out in the experimental area of the Federal University of Fronteira Sul - Campus Erechim, in the 2022/23 harvest. The design used was completely randomized, in a 2x4 factorial scheme, totaling 8 treatments with 5 repetitions each. The treatments consisted of: T1 (without insecticide) and T2 (chemical and biological insecticide); and corn hybrids: AS1757, P2719, P3565, FS533. The analyzed variables were: stunting level; number of plants per meter; number of ears per linear meter; number of rows per ears; number of grains per row; thousand-grain weight; and productivity. The disease index showed no difference between the hybrids when chemical and biological insecticides were not applied. It was observed that the hybrid AS1757 had a higher thousand-grain weight and higher productivity, thus, it was classified as more tolerant to the stunting complex and with a better response to the application of chemical insecticide combined with biological. The hybrids P2719, P3565 and FS533 presented similar values regarding thousand grain weight and productivity, thus they were classified as less tolerant to the stunting complex and with lower productivity in relation to the hybrid AS1757.