KCl depresses physiologic leaf spot of barley (Hordeum vulgare L. 'Duke')

Physiologic leaf spot on barley in the greenhouse was suppressed with KCl fertilization. The area covered by the leaf spot was 8.1% without fertilization, up to 13.7% with K2SO4, but with KCl the amount was only 0.3 and 3.1% for 75 and 25 kg K ha−1, respectively. Suppression of the leaf spotting was not due to K+ or SO42−, but Cl−. Key words: KCl fertilization, Physiologic leaf spot