tomato leaf mold

Symptoms

Pale yellow patches on the upper leaf surface, olive-green to brown velvety mold on the underside directly underneath each yellow patch, severe defoliation leading to fruit sunscald.

Easily confused with

• late blight

  How to tell them apart: Tomato leaf mould (Cladosporium fulvum): pale yellow blotches on the upper leaf surface with an olive-green velvety mould directly beneath them, in humid greenhouses, no water-soaking. Late blight (Phytophthora infestans): greasy water-soaked grey-green lesions with white sporulation, kills leaves and stems fast.

• early blight
• tomato brown rugose fruit virus (ToBRFV)

  How to tell them apart: Tomato brown rugose fruit virus (ToBRFV) is an EU-established tobamovirus: it produces a true systemic MOSAIC — irregular patches of light and dark green plus yellow mottling spread across the whole upper leaf surface — together with narrowing, blistering and fern-like deformation of new leaves, and tell-tale brown wrinkled (rugose) blotches and yellow spots on the FRUIT. The discolouration is purely a colour pattern with no fungal growth and no spores. Cladosporium fulvum (tomato leaf mold) starts as diffuse pale-green to yellow blotches only on the UPPER surface of older lower leaves, but the decisive sign is on the LOWER surface directly beneath each blotch: an olive-green to greyish-brown VELVETY mould of spores. Leaf mold never deforms new growth and never marks the fruit, and it thrives in humid, poorly ventilated greenhouses. If you see velvety mould under yellow spots it is leaf mold; if you see mottled mosaic with deformed leaves and brown rugose fruit and NO mould, it is ToBRFV — a common, EU-established viral disease managed with the usual hygiene, seed and crop-management measures.