Disease

Bacterial leaf spot

Water-soaked spots that turn brown or black, spread by splashing water and hands.

What you'll see

• Small water-soaked or greasy spots that turn brown or black, often with a yellow halo.
• Angular spots boxed in by the veins, or V-shaped patches from the leaf edge.
• Spot centers dry and fall out, leaving holes.

Why it happens

Bacteria spread by splashing water, hands, tools and infected plants or seed cause it. Warm, wet weather favors them.

How to fix it

1. Remove and bin spotted leaves, and discard badly infected plants.
2. Keep the leaves dry: stop misting and overhead watering, and give more air.
3. Wipe tools with 70% rubbing alcohol and wash your hands after handling the plant.
4. A copper spray can slow the spread to healthy leaves but won't cure spots; use it exactly as the label says, keeping kids and pets away.

Keep it from coming back

• Start with disease-free seed and plants.
• Don't work with plants while they're wet.
• Don't replant tomatoes or peppers in last year's spot.

Sources

• UC IPM: Bacterial soft rots, leaf spots, blights, wilts
• University of Maryland Extension: Bacterial leaf spots on indoor plants
• Clemson HGIC: Tomato diseases and disorders

General guidance, not a diagnosis. For valuable, edible or outdoor crops, check with a local extension service or plant expert. Use any product exactly as its label says, and keep children and pets away while it dries.