Diagnosing Bacterial Leaf Spot on Stromanthe

Stromanthe 'Burle Marx' in pot on pebble tray shows small brown leaf spots. Owner questions disease vs. care issue.

Root Check First

Examine roots: abundant, light-colored = healthy. Brown, sparse = root rot (no cure for this species).

Bacterial Leaf Spot Indicators

If roots healthy: hold affected leaf to bright light. Yellow halo between green and brown tissue = bacterial leaf spot.

Management

• Outdoor plants: Remove spotted areas with disinfected scissors (Lysol or 10% bleach). Keep foliage dry. Apply copper hydroxide/sulfate fungicide. Repeat 7-10 days.
• Indoor plants: No safe chemical treatment. Move outside temporarily if possible. Otherwise, remove affected leaves, improve air circulation, avoid overhead watering.

Other Cultural Factors

If no halo: check fertilizer, pH, water quality, light levels. Bacterial spot favored by humidity and wet foliage.