Plant Population and Fungicide Economically Reduced Winter Wheat Yield Gap in Kansas

Abstract

Core Ideas Prophylactic applications of high input rates was not economical in most marketing scenarios The only exception was using low‐cost fungicides and marketing wheat with a protein premium Increased plant population economically reduced wheat yield gap in no‐tillage systems Fungicide application economically reduced wheat yield gap under high‐disease pressure Evidence suggested wheat yield was co‐limited by sink and source in our study Despite the large differences between winter wheat (Triticum aestivum L.) current and potential yields (i.e., yield gap, YG) in Kansas, limited research is available on individual agronomic practices, or their combination, economically increasing yield. Our objective was to quantify the contribution of individual and combined management practices to reduce the wheat YG. An incomplete factorial treatment structure established in a randomized complete block design was conducted to evaluate the effects of 14 treatments on yield, YG, protein concentration, and net returns. The variety ‘Everest’ was evaluated at three locations in 2016 and 2017. We individually added six treatments to a farmer practice control (FP) or removed from a water‐limited yield control (Yw), which received all treatments. Treatments were: additional N, S, Cl, increased plant population, foliar fungicide, and plant growth regulator. Under no‐till which had low disease pressure, the Yw increased grain yield by 0.4 Mg ha−1 as compared with FP, mostly led by additional N, S, increased population, and fungicide (0.2–0.4 Mg ha−1). In conventional till which had high‐disease pressure, the Yw increased grain yield by 1.2 Mg ha−1 as compared with the FP, and foliar fungicide increased grain yield by 1.4 Mg ha−1. Foliar fungicide and increased plant population economically reduced the YG for conventional till and no‐till, respectively. Net return analysis indicated that intensifying wheat management might be justifiable when using low‐cost fungicides and if protein premiums are expected. Our results suggest that an integrated pest management should be preferred over an Yw approach with prophylactic pesticide application.