Effects of Timing of Nitrogen Fertilization and a Fungicide on Soft Red Winter Wheat1

Abstract

AbstractSplit spring N applications and fungicides are important components of proposed intensive management systems for soft red winter wheat (Triticum aestivum L.). Six experiments at two locations were conducted on Hagerstown silt loam (fine, mixed, mesic Typic Hapludalf) soils to evaluate the responses of wheat to a fungicide and delayed or split N applications. Delayed N treatments consisted of a single application of 100 kg ha−1 at either growth stage (GS) 5 or 8. Seven split N treatments consisted of two or three applications made at GS 3, 5, or 8, totaling 100 kg N ha−1. Split and delayed N responses were compared to those resulting from four rates of N applied at GS 3. Average grain yields for the experiments ranged from 3.2 to 5.9 Mg ha−1. Yields from split and delayed N were greater than the maximum achieved with GS 3 N applications in only one of the six experiments. In this experiment, the greatest yield increase due to split N, 0.7 Mg ha−1, occurred when a fungicide was used. A large amount of precipitation (219 mm) at that location between GS 3 and GS 5, and a high fertilizer N requirement apparently contributed to the response to split N. Yield responses to fungicides (triadimefon [l‐(4‐chlorophenoxy)‐3,3‐dimethyl‐l‐(lH‐l,2,4‐trizol‐1‐yl)‐2‐butanone] or triadimefon + mancozeb [zinc ion and manganese ethylene bisdithiocarbamate)) varied between years and ranged from 0 to 0.9 Mg ha−1. Decisions to use split N and fungicides should be based on factors such as disease severity, rainfall, and anticipated soil N supplying capability.