Manejos químico e genético no controle de Xanthomonas vasicola pv. vasculorum e caracteres agronômicos do milho

Abstract

Leaf diseases represent one of the limiting factors for the development of the corn crop in Brazil. In this context, bacteriosis caused by Xanthomonas vasicola pv. vasculorum, as it is a disease with little information about its management, rapid dissemination and difficult to control. Therefore, this study aimed to evaluate the effect of chemical and genetic managements regarding their potential in the control of Xanthomonas vasicola pv. vasculorum and agronomic traits of corn. The experimental design used was randomized blocks, with three replications in a 2x7 factorial scheme, the first factor being the corn hybrids P30F53VYHR, with greater tolerance and P4285VYHR, with greater susceptibility to the disease. The second factor corresponds to the seven products, with the following active ingredients: casugamycin; sulfur; cupous oxide; copper oxychloride; quaternary ammonia; potassium phosphite; control (no application). Products based on quaternary ammonia, cuprous oxide, copper oxychloride and casugamycin provide the greatest disease suppression in the susceptible hybrid, with an area under disease progress curve on average 55% lower than the control. However, none of the products applied, even if promoted or significant control of the disease, has no consequence on corn grain yield. The P30F53VYHR corn hybrid proved to be genetically resistant to the pathogen under study, with results superior to P4285VYHR for all evaluated agronomic traits, with emphasis on grain yield that on average was 19% higher and approximately 13,240 kg ha-1 versus 10,752 kg ha-1, respectively. Thus, the use of genetically resistant material constitutes an efficient alternative for the management of this bacteriosis.