Yield and Disease Control on Hard Winter Wheat Cultivars with Foliar Fungicides

Abstract

Foliar diseases and Fusarium head blight (FHB) (caused by Fusarium graminearum Schwabe) frequently constrain hard winter wheat (HWW) production in the northern Great Plains of North America. Experiments were conducted in North Dakota (ND) to determine the agronomic and economic response of adapted hard winter wheat (HWW; Triticum aestivum L.) cultivars to foliarly applied fungicides. Experiments consisted of a factorial combination of winter wheat cultivars (12–18 depending on the year) and fungicides (no fungicide or fungicides applied) and were conducted in five environments from 2005 to 2007. Yield and disease development varied between environments, with the greatest disease pressure occurring in 2005 and the least in 2006. Within an environment and averaged across cultivars, fungicides improved yields by 5.5 to 44.0%. Cultivars differed significantly in their yield in each environment and cultivar by fungicide interactions for yield occurred in four of the five environments. In all but 2005, varieties that were most responsive to fungicides were those with the greatest disease susceptibility. In 2005, the year of the greatest disease pressure, cultivars that were the most responsive to fungicide were those with the best disease tolerance, indicating the value of integrating several control practices when disease pressure is high. Fungicides were very effective in reducing leaf spots and FHB and provided near complete control of leaf rust. Fungicides can be a valuable tool in increasing yields and profitability of winter wheat, especially if disease susceptible cultivars are grown and if disease pressure is only moderate. Combining fungicides with genetic resistance offers the best monetary return when disease pressure is high.