Black Growths on Lemon Tree Branches: Scale or Aphids?

Black, semi-circular growths on lemon branches with ants nearby suggest scale insects or aphids. Both excrete honeydew, which attracts ants and can lead to sooty mold (black coating on leaves).

Identification Tips

• Aphids: Soft-bodied, usually green/black, move when disturbed. Often on new growth.
• Scale: Hard, immobile bumps (like the "black growths" described). Can be scraped off with a fingernail.

Next Steps

1. Snip an affected twig and take it to a local nursery for positive ID.
2. Based on ID, choose treatment: horticultural oil for scale, insecticidal soap or neem oil for aphids.
3. Control ants with sticky barriers on the trunk—they protect honeydew producers.

Prevention

Monitor regularly, especially in spring. Keep the tree vigorous with proper watering and citrus-specific fertilizer. Avoid broad-spectrum insecticides that kill beneficial predators.