SUMMARYThe effect of net blotch on the growth and yield of cv. Beatrice spring barley was examined in a greenhouse experiment. Separate inoculations at growth stages 21 and 34 reduced green leaf area, root weight, leaf sheath and stem weight and tiller number. The early inoculated plants, which responded and recovered more rapidly than later treated ones, suffered a loss in grain yield and this was related to the amount of disease, the loss in green leaf area and the reduction in unit leaf rate.