Effect of a High-Tunnel, Organic Cropping System on Lettuce Diseases in Western Washington

Fig. 2. Symptoms of disease and disorders on lettuce:  (A) gray mold on heads (left) and crowns (right); (B) lettuce drop on heads (left) and crown tissues with sclerotial formation (right); and (C) tipburn observed in heads (left) and wrapper leaves (right).



Image from Plant Health Progress article:
Effect of a High-Tunnel, Organic Cropping System on Lettuce Diseases in Western Washington