Dose-Response Effects of Seed-Applied Fluopyram and Pydiflumetofen on Soybean Cyst Nematode and Yield: A Component Network Meta-Analysis

Fluopyram and pydiflumetofen are increasingly used in multicomponent seed treatments for soybean cyst nematode (SCN) management, yet their dose-response effects on yield and SCN population dynamics under field conditions remain poorly characterized. A central obstacle is that field trials rarely evaluate identical formulations, so the contribution of any single active ingredient cannot be compared or combined across trials. This study applied component network meta-analysis (CNMA), which decomposes multicomponent treatments into the contributions of their shared active ingredients, across 21 Ohio field trials (2022-2025; 787 plots; 97 treatment entries). Within-trial treatment means were estimated using spatial mixed models with tensor-product P-splines and synthesized by mixed-effects meta-regression. Pydiflumetofen exhibited a positive dose-dependent yield response that increased with SCN egg density at planting (P = 0.025); whereas the corresponding response of fluopyram was smaller (P = 0.057). At the labeled 1× rate, predicted pydiflumetofen yield gains rose from 33.6 kg/ha at low SCN pressure (500 eggs/100 cm³) to 150.4 kg/ha at high pressure (10,000 eggs/100 cm³). Effects on final SCN population density were small and inconsistent: fluopyram produced dose-responsive reductions of 4.0%, 7.8%, and 12.7% at the 1×, 2×, and 3.33× rates (all P > 0.05), whereas pydiflumetofen effects were negligible (≤1.2%). Yield responses therefore increased with SCN pressure without corresponding reductions in final SCN density. To our knowledge, this is the first application of CNMA in plant pathology, offering a framework for evaluating dose-response effects in multicomponent crop protection products under field conditions.