Estratégias de controle químico da mancha branca na cultura do milho

Abstract

The white spot is one of the important leaf diseases in the corn crop in Brazil, causing losses of production and it is difficult to control. The objective of the work was to evaluate, under field conditions, the influence of the application of fungicides of the chemical groups triazole, strobilurin, carboxamide and dithiocarbamate, as well as their mixtures, in different phenological stages for the control of pathogens that cause white spot in the culture of the corn. The experiment was installed and conducted in the second harvest, under field conditions, at Fazenda Horizonte (18 ° 55'08 '' S, 48 ° 03'45 '' O, at 850 m altitude), located in the city of Uberlândia - MG. During the period from 02/02/2019 to 06/30/2019. The experimental design was carried out in randomized blocks, with five treatments and four repetitions, varying fungicides already registered as commercial products at different times of application, one treatment being control test and the others composed by different combinations of fungicides (trifloxystrobin + tebucoconazole), (trifloxystrobin + protioconazole + bixafem) and mancozeb. The characteristics evaluated in the test were plant stand, plant height, spike insertion height, percentage of green leaf area in R6, severity of the white spot, area under the disease progress curve (AACPD), stem density and productivity. The plant stand, plant height and spike insertion were not influenced by the treatments evaluated. All treatments had a higher stem density compared to the control, but they did not differ from each other. Treatments T3 [(trifloxystrobin + tebucoconazole) V8 and (trifloxystrobin + tebucoconazole + mancozeb) VT and R2], T4 [(trifloxystrobin + tebucoconazole) V8 and (trifloxystrobin + protioconazole + bixafem) VT and R2] and T5 [(trifloxystrobin + protioconazole + bixafem) V8, VT and R2] had the lowest AACPD, highest grain yields and maintenance of green leaf area. The addition of dithiocarbamate with triazole and strobilurin proved to be effective, as well as the addition of carboxamide to control the pathogen complex that causes the white spot, in addition to ensuring greater productivity, being superior to the mixture of strobilurin and triazole, which is also proved effective when compared to the control.