Hops reportedly use about 610 to 715 mm (24 to 28 inches) of water per year (Evans 2003). Rainfall can contribute to this total, however, due to climatic variability, it is important that hops are irrigated regularly to combat moisture stress. Moisture deficit during the hop growing season has been shown to cause reductions in hop cone yield (Hnilickova et al. 2009). Irrigation systems can help to alleviate some of the potential drought stress, but timing of water application is just as important as the amount of water hops are receiving. Hops require the majority of their water in the critical period between training and flowering for optimal vegetative growth. The hop yard is irrigated through a well-fed drip irrigation system, which delivers 3000 gal ac-1 each week, beginning in late May. Over the 14-week irrigation period, this equates to 1.54 inches of water, or 0.11 inches each week, which is well below the 23.5 inches required, adjusting for potential evapotranspiration. The goal of this project was to evaluate differences in yield, insect pests, and disease presence between plants at the Borderview Research Farm that were watered at the optimal level, and plants that were irrigated at the level sustained by the on-farm well.
Vermont, University of Vermont
Darby, Heather; Cubins, Julija; Lewins, Scott; and Post, Julian, "Hop Optimal Irrigation Trial" (2016). Northwest Crops & Soils Program. 97.