Eficácia de diferentes estratégias de controle químico em doenças foliares do milho

Abstract

Maintaining plant health is crucial for a good development of the maize crop, since a small decrease in leaf area can lead to losses in the production of photoassimilates and, consequently, in grain production. Thus, foliar diseases limits the plant to express its productive potential. Chemical control through fungicides is essential in reducing foliar diseases. Therefore, the objective of this work was to evaluate the effectiveness of different chemical control strategies of maize foliar diseases, under conditions of second crop. The experiment was conducted in Uberlândia - MG, in the second crop of the 2021/2022 agricultural year. The hybrid used was STATUS VIP3. The experimental design was randomized blocks, in which the hybrid was submitted to 8 treatments. The treatments were combinations of fungicides from the chemical groups trizols, strobilurins, carboxamides and isophthalonitriles, at different times of application, in addition to the control treatment in which no fungicide was applied. The characteristics evaluated were: plant height, ear insertion height, final stand, leaf disease severity, green leaf area and grain yield. Treatments T7 (difenoconazole + azoxystrobin V8 and R2 / difenoconazole + pydiflumetofen VT / chlorothalonil R2) e T8 (difenoconazole + azoxystrobin V8 / difenoconazole + pydiflumetofen VT and R2) proved to be more effective in controlling leaf diseases, by obtaining the lowest leaf disease severity averages and keeping the highest values for green leaf area. The third application in R2 also contributes to the maintenance of plant health. For productivity, only T2 (difenoconazole + azoxystrobin V8) presented an average similar to the control. Treatments T5 (difenoconazole + azoxystrobin V8 / difenoconazole + pydiflumetofen VT), T6 (difenoconazole + azoxystrobin V8, VT and R2 / chlorothalonil VT and R2), T7 and T8 obtained the best averages for this character, not differing from each other. The addition of pydiflumetofen to the strategy proved to be efficient in controlling foliar diseases, as treatments with a carboxamide were superior to those with just a triazole and strobilurin.