I have read a number of posts on the same topic, "healthy" lemon tree dropping leaves, here, here, here, here, here, and even this post from my same city (Vancouver). The general guidance seems to soil ph (which I need to test) and moisture level issues.
My specific circumstance ... This is one of 8 Lemons and 2 Limes grown from seedling. All either 3 or 4 years old. Kept outdoors in the summer, indoors in winter (14 - 18 °C), under a combination fluorescent regular and grow light and E-facing window. All have been watered lightly (winter) once a week and citrus fertilizer or Schultz alternating every 3-4 weeks (1/2 strength). Misting foliage regularly.
Identified a minor scale infestation (< 50 per plant), so manually inspected leaves on all 10 plants, removed all visible bugs, and applied dormant tree insecticide. All the others doing well.
This one suddenly suffering from leaf drop, now 50-60/day and almost gone! All the leaves look healthy, no bugs, no mites that I can see, Looks as if some ring chokes it at the stem then falls off, usually leaving the stub, which then falls.
This was actually the biggest plant of the bunch, and my favourite, so, really want to save it!
- Is there still a bug infestation on this one?
- Watering issue?
- Do we just prune it back and hope for new growth ?
