Carboxamidas associadas a multissítios para controle de mancha-alvo em soja

Abstract

Soybean (Glycine max L. Merrill) is increasingly showing the importance for the national economy due to the multiple uses. However, the incidence of diseases can lead to losses in productivity and product quality. One of the diseases that has been gaining importance in this scenery is the target spot, caused by Corynespora cassiicola. Thus, the objective was to evaluate the efficiency of carboxamides, with or without multisites fungicides, to control target spot on soybean yield and productivity. The experiment was conducted in experimental area of the Universidade Federal da Fronteira Sul - Campus Erechim in the 2022/2023 crop season. The cultivar used was BMX Garra in a randomized block design with 8 treatments and 4 replications. Inoculation of Corynespora cassicola isolates was carried out when the plants were in the V6 phenological stage and the experiment was conducted under sprinkler irrigation conditions. The treatment T1 was the control and didn’t receive fungicide applications. The other treatments received sequential apllications, as follows: T2: (fluxapyroxad + prothioconazole); T3: (fluxapyroxad + prothioconazole) + mancozeb; T4: (bixafem + prothioconazole + trifloxystrobin); T5: (bixafem + prothioconazole + trifloxystrobin) + mancozeb; T6: (impirfluxam + tebuconazole) + (difenoconazole + ciproconazole); T7: (metominostrobin + impirfluxam + chlorothalonil); T8: (impirfluxan + tebuconazole) + mancozeb. The area under the disease progress curve (AUDPC) was estimated based on target spot severity evaluations, as well as the control (%); in addition, was determined number of grains per pod, number of pods per plant, weight of one thousand grains (WTG) and the productivity. Treatments with the active ingredient prothioconazole showed less disease progress and higher disease control percentages compared to the control. Treatment T2 (fluxapyroxad + prothioconazole) provided 77.8% target spot control in soybean cv. BMX Garra. In this treatment, better results were also obtained for the number of grains per plant and pods per plant, reflecting the improvement in the phytossanitary aspect of the plants provided by T2. Due to the high disease pressure, it was not possible to differentiate the effect of the carboxamide impifluxam combined with mancozeb and chlorothalonil, as they showed low efficiency in target spot (less than 30% in the average of treatments). The carboxamide impirfluxam combined with difenoconazole + cyproconazole (T6) and mancozeb (T8) demonstrates a beneficial effect on the thousand seed weight, with the highest values (184 and 179 g, respectively). Therefore, the combinations of site-specific fungicides and mancozeb (T3 and T5) provided the highest yields (average of 3645 kg ha-1 between treatments), consisting of 60.7 sc ha-1 ).