Common Tomato Diseases: How to Identify & Treat Them (with Symptoms)

Updated 2026-07-10 · Pest & disease

Tomato is one of the most disease-prone crops, and catching a problem early is the difference between a light spray and a lost field. Here are the four you are most likely to see, how to tell them apart, and what to do.

Early blight — brown target-ring spots on lower leaves

Symptoms: dark brown spots with concentric rings (a "target" look) on older, lower leaves first, often with a yellow halo; leaves dry and drop.
What to do: remove affected leaves, improve airflow, avoid wetting the foliage, and spray a protectant fungicide (e.g. mancozeb or chlorothalonil) early. Rotate crops — do not plant tomato after tomato or potato.

Late blight — fast, water-soaked patches in cool wet weather

Symptoms: irregular greasy, water-soaked grey-green patches on leaves that spread very fast, with white mould underneath in humid weather; fruit develops firm brown lesions. It can destroy a crop in days.
What to do: act immediately — remove and destroy infected plants, and spray a late-blight-specific fungicide. Prevention matters most: resistant varieties, wider spacing and no overhead watering in cool, damp spells.

Leaf curl (viral) — curled, thickened, yellowing leaves

Symptoms: upward curling, crumpling and yellowing of leaves, stunted plants and poor fruit set. It is a virus spread by whiteflies.
What to do: there is no cure once infected — remove badly affected plants. Control it by managing whiteflies (yellow sticky traps, neem), using virus-resistant varieties, and keeping the field weed-free.

Bacterial wilt — sudden wilting with green leaves

Symptoms: the plant wilts suddenly while the leaves are still green, often on one side first, and does not recover at night; a cut stem placed in water oozes a milky stream.
What to do: remove infected plants, improve drainage, rotate away from tomato/brinjal/chilli/potato for several seasons, and use grafted or resistant varieties in problem soils. There is no effective chemical cure.