Resumo

PLOPER, L. Daniel et al. Experiments using foliar fungicides in soybean crops during 10 growing seasons in Tucumán, Argentina. Rev. ind. agric. Tucumán [online]. 2015, vol.92, n.1, pp.17-38. ISSN 1851-3018.

This paper reports the results of field experiments conducted by Estación Experimental Agroindustrial Obispo Colombres (EEAOC) during 10 growing seasons, to evaluate foliar fungicides in the management of late season diseases (LSD) and soybean rust in Northwestern Argentina. The trials were located at EEAOC Monte Redondo Substation (in San Agustín, Cruz Alta department) from the 1998/1999 through the 2007/2008 growing seasons, and on commercial farms in Puesto del Medio and La Cruz (Burruyacú department, Tucumán) from 2005/2006 through 2007/2008. Fungicides from different chemical groups were evaluated in variable numbers depending on the trials. They were applied at different growth stages, using the rates recommended by manufacturers. Double applications were evaluated during the first three seasons, and single applications in the remaining ones. Parameters evaluated included defoliation percentage at R7, degree of stem colonization by LSD, rust incidence and severity, yield and significant yield increase in treated plots with respect to the untreated control, as well as incidence of microorganisms in seed. The results revealed that under adequate conditions, LSD and rust affected both crop yield and seed quality. Under fungicide treatments, crop yield was 3% to 32% higher than that of the untreated control, depending on the growing season considered. Even though no yield differences were found between single and double fungicide applications against LSD, more than one application might be needed in an early rust detection scenario. As far as application dates were concerned, yield response was random. All in all, treatments led to higher yields than the untreated control, except for the 2004/2005 season. No net differences could be attributed to specific crop stages, and each season showed distinct patterns.

Palavras-chave : Glycine max; ate season diseases; soybean rust; Phakopsora pachyrhizi; chemical control.

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