High Humidity Levels Negatively Impact Quality of Lettuce.

Bacterial leaf spot, caused by Xanthomonas campestris, represents a threat to lettuce crops since this pathogen thrives in conditions of high relative humidity (80-100%) during the phenological phase of leaf development. Symptoms include water spots on the leaves with angular edges, surrounded by veins, which can transform into fused lesions, causing the affected leaves to collapse.

Source: https://edis.ifas.ufl.edu/publication/HS1412