Bacterial canker
Symptoms
Quite rare, but if it attacks, it can destroy the entire season's harvest. The main symptoms are wilting, curling, and browning of leaves. Initially, not the entire leaf wilts, only a part of it. Even if the plant is infected at the seed stage, symptoms may not appear until flowering. Later, spots with a double border appear on the fruits. The disease spreads rapidly — infected plants must be removed immediately.
Control and prevention
Treatment is only effective when the plant is young. An infected plant must be destroyed and the soil "treated"; do not plant tomatoes in that spot for two years. Collect seeds only from healthy plants, sow in sterile soil.
Related problems
Similar symptoms might indicate a different cause — compare them.
Bacterial spot
Manifests as dark spots with a raised center on leaves and stems, later the leaves begin to yellow. Dark, growing spots may appear on the fruits. Cool, humid weather and splashing water droplets allow the disease to spread rapidly.
Early blight and black fruit rot
Alternaria solani
Usually appears when fruits begin to set. First affects the lower leaves, then the stem and fruits. Large brown or black spots with concentric rings appear on them. Around the spot, the leaf begins to yellow and dies. It also attacks potatoes and eggplants. The fungus is resistant and persists for several years.
Late blight
Phytophthora infestans
Dark green or black spots appear and spread on the edges of the leaves. The same can appear on the fruits.