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Effect of the number of fungicide applications on the control of Asian soybean rust

This work aimed to evaluate the effect of the number of leaf applications of fungicides on the control of the Asian soybean rust. The experiment was carried out at the 2003/04 cropping season, in Viçosa, state of Minas Gerais, Brazil. The experimental design was a randomized block design, consisting of four replicates. The following treatments: control without application, one application at stage R5; two applications at R4 and R6; and three applications at R4, R5 and R6. The fungicides pyraclostrobin + epoxiconazole and carbendazin. After it analyzes her of variance and test of averages, it was verified significant reductions of 91.6 and 97.5% on severity of soybean rust, and of 100 and 86.8% on the percentage of defoliation were detected when three applications of the fungicide mix (pyraclostrobin + epoxiconazole) were applied on the cultivars Vencedora and Conquista, respectively. The results showed a delay in the cycle, reduction on abortion of beans and an increase on weight per 100 seeds on the treatments where both varieties received fungicide applications. The highest yields were obtained on the treatments that received three applications of the fungicide mix (pyraclostrobin + epoxiconazole). However, there was no significant difference among the treatments with one, two or three carbendazin applications.

Phakopsora pachyrhizi; severity; yield; Glycine max


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