Controle preventivo de doenças foliares em híbridos comerciais de milho com fungicidas em espaçamento reduzido

Abstract

The objective of this research was to evaluate the effect of triazole and strobilurin fungicides, alone and in combination, in disease control in commercial corn hybrids with reduced spacing in different agricultural crops. The experimental design was a randomized block design in a factorial 4x6, and fungicide treatments (control; Cyproconazole ; Trifloxystrobin; Trifloxystrobin + Prothioconazole; Trifloxystrobin + Tebuconazole and Trifloxystrobin + Cyproconazole) and four corn hybrids (DKB240Y, P32R48H, P30F53H e BG7051H), with three replications , totaling 72 plots in the growing seasons 2011/2012 and 2012/2013. The experimental area was in Farm Três Capões , as the plots consisting of six rows (5.0 m long x 0.45 m between - row) , with a total area of 13.5 m² floor area and consists of the central rows (3 and 4). There was a reduction in the area under the disease progress curve (AUDPC) leaf, common rust, leaf spot Diplodia and Helmintosporium blotch, with the use of fungicides, alone and in combination, depending on the hybrid and harvest evaluated. The application of a preventive fungicide isolated triazole and triazole fungicide estrobirulina and in combination, reduced the AUDPC leaf rust (P. sorghi) and leaf spot Diplodia (S. macrospora), and its outcome depends on the used hybrid and harvest. Was reduced to AUDPC of Helminthosporium (E. turcicum) fungicides when applied preventively associations (triazole and strobilurin) when compared to the single treatments and the control, regardless of the hybrid used. There was no reduction in the incidence of damaged kernels using fungicides applied preventively in corn hybrids evaluated, and its result influenced by harvest. The application of a preventive fungicide in combination, resulted in an increase in yield in the corn hybrids utilized, the effect being variable according to the harvest.