The influence of a natural infection of net blotch, caused by Pyrenophora teres Dreschl., on the yield and quality of Beecher barley was determined. The disease was controlled in some of the experimental plots by spraying with fungicides at regular intervals. The highest yield (51.9 bushels per acre) and the lowest leaf infection score (24 per cent of the maximum value) were on plots sprayed with Manganous ethylene bisdithiocarbamate (Maneb). By contrast the yield on the unsprayed plots was 17.4 per cent lower and the leaf infection score 28 per cent higher. Bushel and kernel weights were depressed by infection and the proportion of small grains increased. Grain from plots sprayed with Maneb yielded 2.8 per cent more extract of malt than grain from the control plots. The nitrogen content of the grain was not significantly affected, and the saccharification rate was similar for all treatments.