Brown Leaf Spot (Cladosporiosis)

Brown leaf spot is a disease caused by the fungus Passalora fulva (formerly Cladosporium fulvum). It occurs mainly in plastic tunnels and greenhouses, where high humidity persists. Light yellow spots appear on the upper surface of the leaves, while the underside develops a characteristic olive-brown, velvety coating. Over time, the leaves turn yellow, dry out, and die prematurely, which limits photosynthesis and reduces yield. The best protection is good tunnel ventilation, avoiding excessive humidity, and growing varieties with genetic resistance.