Eficiência da calda bordalesa no controle do colletotrichum truncatum na cultura da soja

Abstract

Among the impacts of soybean cultivation in Brazil are the high cost of production and environmental factors. The tropical climate provides ideal conditions for the proliferation of pathogens in this crop. In this way, it is essential to use agrochemicals to combat them and stimulate productivity. In this context, products less invasive to the environment are highly encouraged by agroecological groups. In this work, the influence of the Bordeaux mixture as an environmentally correct fungicide on several agronomic characteristics of AN 8270 CV soybean cultivar was analyzed. Each experimental plot occupied a total of 5 m2, with a stand of 13 plants per meter and spacing of 0.45 m between rows. Fungicide, insecticide and micronutrients were used in seed treatment, as well as previous pH corrections and soil fertilization. Bordeaux formulations were prepared using 500, 1000, 1500g CuSO4.3H2O and equal amounts for CaO (calcium oxide). An additional treatment was performed with 1000g of CuSO4.3H2O and 1000g of urea, plus to CaO. All treatments used a volume of 100 liters of ha-1 which were applied to V4, V7 and R1. The experimental results indicated that the lower concentration of CuSO4 was better in the preparation of the Bordeaux curd applied as fungicide in soybean cultivars, since there were no significant differences in productivity (Tukey, p <0.05) in relation to the other treatments and was more efficient in the fight against Anthracnose in soybean. High amounts of CuSO4 resulted in a decrease in the incidence, but were not efficient in controlling the severity of this disease. The lowest concentration still influenced positively the yield components: dry matter yield, number of pods, first pod insertion and length of shoot. At the end of the experiment it was noted that no treatment caused injury to the culture, or otherwise affected its physiology. The importance of these results from the economic and environmental point of view is emphasized, since at the same time productivity can be favored and the pathologies reduced, reducing the amount of waste generated during the application.