Leaf mold of tomato

Leaf mold of tomato, caused by the fungus Fulvia fulva (synonym Cladosporium fulvum), is a destructive foliar disease that primarily affects tomato plants grown in protected environments such as greenhouses and high tunnels. It is considered one of the most common and difficult-to-control fungal pathogens in commercial and home tomato production.

The disease targets the foliage, rarely affecting stems or fruits. The pathogen is highly host-specific, primarily infecting plants within the Solanaceae family. Its ability to produce massive amounts of spores allows it to spread rapidly throughout a greenhouse facility via air currents, water splashes, and human activity.

Symptoms typically begin on the lower leaves as pale or yellowish spots on the upper surface. Correspondingly, on the underside of these spots, a dense, velvety, olive-brown mat of fungal conidia develops. As the disease progresses, the leaves wither, curl, and turn necrotic, leading to early defoliation and a significant reduction in the plant's yield potential.

Development of the fungus is favored by high relative humidity (above 85%) and warm temperatures (ranging from 20°C to 25°C). The spores exhibit remarkable resilience, capable of surviving for long periods in soil, on greenhouse structures, or within plant debris, which serves as the primary inoculum source for subsequent crop cycles.

Integrated management is essential for effective control. This includes improving greenhouse ventilation to lower humidity, implementing strict hygiene practices, and removing infected leaves at the earliest sign of disease. Furthermore, the use of resistant tomato cultivars is currently the most sustainable and efficient strategy to mitigate losses caused by Fulvia fulva.

• Maintaining adequate spacing between plants to improve air circulation.
• Strict sanitation and removal of crop residues.
• Utilization of fungicides registered for use against leaf mold.
• Optimizing irrigation to avoid foliage wetting.