Controle de doenças de final de ciclo na cultura da soja

Abstract

In the years of 2003 and 2004, at Federal University of Santa Maria, Rio Grande do Sul, Brazil, experiments for evaluation of control of antracnose and late season diseases on soybean had carried. First experiment, had been evaluated 49 cultivate soybean (Glycine max Merril.) for genetic resistance to Colletotrichum dematium var. truncata, in the stadium V1/V2. Of these cultivars, six had been selected by the reaction to the inoculation for the pathogen (two resistant, two intermediate and two susceptible), and submitted the inoculation for four isolated of C. dematium var. truncata in the stadium V5/V6, being evaluated the reaction in accordance to the age of the plant. These reactions had been determined from a scale of severity of symptoms, that varied of 0 to 9, and that it was used to determine the indices of virulence of the isolates and resistance of cultivars. The results of inoculation in stadium V1/V2 had shown to differences in the reaction of the 49 cultivars inoculated, with three cultivars susceptibles, eighteen resistant and twenty-eight intermediate. For the inoculations in stadium V5/V6, the results had shown a resistance increase, in comparison with same the cultivar inoculated in V1/V2, demonstrating the effect of "resistance of adult plant". In the second experiment, a group of different experiments had been evaluated, objectifying the chemical control in differents cultivating soybean and different places (Itaára, Júlio de Castilhos and Não-Me-Toque, RS, Brazil), using different active principles. The results had shown the responses of the different cultivars to the chemical control, having been observed variation in the capacity of these cultivars in answering to the control programs. It did not observe superiority of any fungicidal group, nor trend in the variation of control efficiency in the different places, but between localities. The different control programs, in the same place, make possible differences in the maintenance of the responsible leaves components for the yelds. The best positionings of control had shown to be in the phenologic stadiums R4 and R5.1.