Efeitos de fungicidas no tratamento de sementes de soja sobre Colletotrichum Truncatum, Cercospora Kikuchii e Fusarium Semitectum.

Abstract

It is known that soybean seeds are a vehicle of pathogens, causing a proliferation of undesirable diseases, often already known by the local producer, or introducing a new pathogen in the location, and for better control of this situation, it is recommended the seed treatment, and thus performing a better control of diseases that may manifest themselves in the culture to be established. Given this scenario, the present work aimed to evaluate pathogens present in lots of field seeds, through the filter paper method (Blotter test), as well as to evaluate the effect of 16 chemical products in the management of these pathogens. Therefore, the objective of this work was to evaluate the incidence of Cercospora kikuchii, Colletotrichum truncatum and Fusarium semitectum in seeds treated with fungicides. Other diseases, such as Cladosporium sp., Phomopsis sojae, Penicillium spp., Aspergillus flavus, were analyzed, where the treatments used effectively controlled these pathogens, thus not requiring statistical analysis of these pathogens. The fungicides used were from the chemical groups strobilurins, triazoles, isophthalonitriles, organostannins, morpholine, bezimidazoles, carboxamides, pyrazoles, alkylenebis, and fermented fungicides, seeking the performance of different classes of fungicides, to better distinguish the effectiveness of fungicides. After the application of treatments, the seeds were incubated for 7 days, at 20° C with a variation of 2°C more or less, with the aid of photoperiod lights and a controlled environment. In each treatment 300 seeds were evaluated. The experiment was conducted in the laboratory of the Federal University of Uberlândia - MG, in a randomized block design, with 17 treatments and three repetitions. The evaluations are done using a microscope, for better identification and quantification of the fungus present, and thus, counted per gerbox, to obtain the exact amount of each fungus in each treatment, and observe the efficiency of each treatment. For control of Fusarium semitectum, the treatments T5 (Tebuconazole + Chlorothalonil), T13 (Bixafem + Prothioconazole + Trifloxystrobin) and T14 (Benzovindiflupir + Prothioconazole), whose commercial names are, respectively, Fezan gold, Fox Xpro and Mitrion, stood out. For control of Fusarium semitectum, the one that showed the worst results was the control control. Treatments that were intermediate according to the statistics were T3 (Trifloxystrobin + Cyproconazole), T7 (Metiram + Pyraclostrobin), and T12 (fermented fungus). For control of Cercospora kikuchii, treatment T6 (Fentin hydroxide) stood out. For control of Cercospora kikuchii, the worst treatments were the witness, followed by T3 (Trifloxystrobin + Cyproconazole), and T13 (Bixafem + Protioconazole + Trifloxystrobin). For control of Colletotrichum truncatum, all treatments stood out, except the witness and T4 (Chlorothalonil).