Associação de mancozebe com formulações comerciais mistas de fungicidas no controle da ferrugem asiática da soja

Abstract

The emergence of resistant populations of Phakopsora pachyrhizi to some fungicides used in its control has generated concern in Brazil. The objective of this study was to evaluate the control of asian soybean rust by the association of mancozeb multiple ingredient active commercial fungicides with. Seven experiments were conducted on soybean crop, 2015/16 season. In experiment I, five fungicidal control programs (azoxystrobin + benzovindiflupir, azoxystrobin + ciproconazol, picoxystrobin + ciproconazol, pyraclostrobin + fluxapiroxade and a control without application) with or without mancozeb were tested. In experiment II, eleven fungicidal programs, involving applications in association with mancozeb and/or different moments of application, were tested. Applications were done at the vegetative, reproductive and pod filling stages, varying the moment of association with mancozeb or isolated. In The experiment III, seven mancozeb doses (0, 553, 750, 938, 1125, 1312, 1500 g ha-1) were combination with multiple ingredient active commercial fungicide picoxystrobin + cyproconazol. The first trial was replicated at three sites (Dourados, Ponta Porã and Vila Vargas), while experiments II and III were implanted in Ponta Porã and Vila Vargas. Three applications were carried out with CO2 pressurized sprayer in experiments I and II and additional applications in trial II, according to the treatments, in delimited plots with an area of 18.90 m². Analysis of the area under the FAS lesion progression curve and yield showed that the addition of the multi-site fungicide in multiple ingrediente active comercial fungicides resulted in a reduction in disease severity of 46% and an increase in productivity. The association with mancozebe fungicide also reduced the level of incidence and severity of the anthracnose (Colletotrichum dematium var. truncata) of soybean. There was no increase in control in the applications performed at vegetative stage, in comparison to the applications of flowering start. There was a linear reduction in the intensity variables of the disease with increasing dose of mancozeb, reduction of defoliation and gain in productivity. The association of mancozeb with azoxystrobin + benzovindiflupir did not result in an increase in control efficiency. The use of the multi-site fungicide associated to commercial mixtures, besides recovering and increasing the efficiency of the commercial fungicide mixtures, is a tool in the resistance management of the P. pachyrhizi fungus.