Distinguishing Environmental Leaf Spots from Disease on Wax Begonias

Distinguishing Environmental Leaf Spots from Disease on Wax Begonias

Four wax begonias (Begonia semperflorens) from Lowe's ($1) have white droplets/spots on leaf edges. Some spots have red halos; others are lacey. One plant is spotless.

Begonia 10

Begonia 11

Analysis

• Not powdery mildew (that looks like dusted flour).
• Not mealybugs (those are tufts on stems).
• Could be fertilizer granules (Osmocote): Round, BB-sized, develop liquid centers—often mistaken for eggs.
• Contact injury: Spots with red halos suggest localized trauma (handling, chemical splash).

Recommendation

1. Remove heavily spotted leaves (they won't recover).
2. Monitor new growth—if clean, the issue was a one-time event.
3. Water at base, avoid wetting foliage.
4. Fertilize lightly with balanced liquid feed.

These are likely environmental/handling marks, not an infectious disease. The spotless plant confirms the batch wasn't uniformly diseased.