Impacts of diverse chemical inputs on soybean disease dynamics and crop performance

Resumo

Late-season diseases (LSDs) are among the most important biotic constraints on soybean yield, often requiring effective chemical management strategies to mitigate their impact on crop health and yield. In this context, this study was developed to evaluate the effectiveness of carboxamide-based fungicide programs in controlling LSDs in soybean. The experiment was carried out in Pinhalzinho, São Paulo, Brazil, using a randomized complete block design (RCBD) with five treatments and four replicates. Treatments consisted of four fungicide management programs including carboxamides and one untreated control (checkplots without application). Fungicide applications began 27 days after sowing (DAS) and were repeated at 15-days intervals following disease detection. Evaluated variables included disease severity, area under the disease progress curve (AUDPC), number of pods per plant, number of seeds per pod, grain yield (kg ha⁻¹), and thousand-grain weight. Data were analyzed using analysis of variance (ANOVA) and means were compared by Tukey’s test (p ≤ 0.05). Carboxamide-based treatments reduced the progression of target spot and brown spot. However, no differences among treatments were observed for yield components, including number of pods, thousand-grain weight, and grain yield. Overall, carboxamide-based fungicide programs effectively reduced disease severity but did not influence soybean yield.