Bacterial Leaf Spot 🦠
At a glance
- Cause: Bacteria spread by splashing water, tools, hands, and infected plant material
- Tell-tale sign: Water-soaked or angular spots, often with yellow halos
- Severity: Moderate — can spread fast in warm, wet, crowded conditions
How to identify
Bacterial leaf spot often begins as water-soaked, translucent-looking spots that turn brown or black. Spots may be angular because veins limit their spread, and yellow halos are common. On houseplants, repeated misting, crowded leaves, and wet foliage can make bacterial spotting worse.
What causes it
Bacteria enter through natural openings or wounds and move in splashing water. Warmth, wet leaves, close spacing, and contaminated tools increase spread.
Treatment & management
Following Integrated Pest Management:
- Isolate the plant if it is indoors.
- Remove infected leaves with clean tools; disinfect tools afterward.
- Stop misting and overhead watering; keep leaves dry.
- Improve airflow and spacing.
- Discard severely infected plants if spotting continues to spread despite sanitation.
Prevention
Buy clean plants, avoid wet foliage, do not crowd plants, and sanitize tools between suspect plants.
Affects (in this guide)
Many ornamentals and houseplants, especially begonias, anthuriums, philodendrons, and crowded greenhouse-style plants