CONTROLE ALTERNATIVO, BIOLÓGICO E QUÍMICO DO MOFO BRANCO NA SOJA

Abstract

The white mold of soybean, caused by Sclerotinia sclerotiorum, is causing great damage to the soybean crop in Brazil. It is a polyphagous fungus hard to control because it produces resistance structures called sclerotia, which can remain viable in the soil for several years. Aiming its control, various management strategies should be used as the control with alternative substances, biological control agents and fungicides. Thus, nine experiments were conducted in naturally infested areas by white mold in 2011/12 season in the counties of Arapoti/PR, Mauá-da-Serra/PR and Pinhão/PR, with an experiment of alternated control, a biological control and one of chemical control conducted at each site. The variables analyzed were incidence, severity, yield and numbers of sclerotia produced. The objective of the experiments of alternative control was to assess different alternative substances, foliar sprayed, isolated or combined with the fungicide fluazinam, for control of white mold in soybean. The alternative substances applied were sodium dichloroisocyanurate, benzalkonium chloride, pyrolysis extract, sodium hypochlorite, cobalt + molybdenum, sucrose, sodium bicarbonate and acibenzolar-S-methyl. As conclusions, it was observed that alternative substances applied in combination with the fungicide fluazinam provided lower severity of white mold in soybeans on the experiment conducted in Pinhão – PR, and fungicide fluazinam applied alone or in combination with alternative substances was effective in control of white mold in soybeans in locations with high incidence of the disease. The objective of the experiments of biological control was to evaluate different biological control agents sprayed foliar compared to the untreated control and the fungicide Fluazinam for control of white mold in soybean. The biological control agents used were: Thichoderma harzianum SC; Thichoderma asperellum EC; Thichoderma asperellum WG; Coniothyrium minitans and Bacillus subtilis. As conclusion, the biological control agents were not effective in controlling white mold of soybean in the conditions that were tested, and the fungicide fluazinam demonstrated lower incidence and severity of disease and higher yield of soybean when applied in areas with high potential inoculum. Finally, the objective of the experiments of chemical control was to verify the efficiency of the control of white mold in soybeans with the use of fungicides applied alone, in rotation, at different growth stages and in a mixture of two active ingredients. The fungicides used were carbendazim, thiophanate methyl, procymidone and fluazinam. As conclusion, the use of fungicides were effective in controlling the incidence and production of sclerotia of S. sclerotiorum in soybean, especially the combinations that had two or more applications of the active ingredient Fluazinam.