Controle de podridão da haste (fusarium oxysporum e diaporthe ueckeri) em sementes e plantas de soja

Abstract

The occurrence of stem breakage and pod and seed rot has become increasingly frequent in soybean crops across various producing regions in the country. These symptoms are associated with the fungal complex of the species Diaporthe ueckeri and Fusarium oxysporum. This study aims to evaluate the efficiency of fungicides in controlling Diaporthe ueckeri and Fusarium oxysporum in in vitro tests (Petri dishes), seed treatment, and in vivo (greenhouse) conditions. The in vitro experiment was conducted in a completely randomized design (CRD), with five replicates, in Petri dishes, evaluating 24 products incorporated into PDA (potato dextrose agar) medium, with fungal mycelial disks added. These were then stored in a cold chamber, and mycelial growth was assessed at 3, 7, 10, and 14 days after inoculation. Following this, the seed treatment experiment was conducted in a CRD, using seeds of the cultivar Desafio RR. Specifically, the seeds were inoculated with the pathogens and treated with 9 commercial products. Each treatment consisted of 200 seeds, using the blotter test method. Subsequently, evaluation was performed after 7 days, assessing the number of seeds showing fungal signs. In addition to the in vitro and seed treatment experiments, two experiments were conducted in the greenhouse using a randomized block design (RBD). The first experiment had 10 blocks in a double factorial scheme with two cultivars (Desafio RR and Exata I2X), 9 fungicides + 1 control. For this experiment, three plants per cup were grown, constituting the experimental plot, with inoculation performed using the straw test method when the plants were at the V1 stage, followed by product application. After a period of 21 days post-inoculation, the plants were removed for evaluation, and the size of internal stem necrosis was analyzed. Similarly, the second greenhouse experiment was conducted with five blocks, 16 fungicides + 1 control, using the cultivar Desafio RR. In this case, two plants per cup were grown, repeating the same methodology as the first greenhouse experiment. Finally, data from all the experiments were analyzed using Tukey's test at 5%. Overall, the results demonstrate that the correct choice of active ingredient for different situations, depending on their characteristics, is crucial for effective pathogen control.