My Benjamina Ficus developed white soft balls at the back of the leaves and they started falling. I took it outside, pruned it severely, hosed it thoroughly, and sprayed the leaves with a solution of potassium bicarbonate. Your initial response to my question was that you thought it was scales. But they are not scales. Just white soft wax like bubbles. The plant is now outdoors, and seems to be surviving. I had another Benjamina with the identical leaf bubbles and it died indoors in a two weeks – every leaf dropped to the floor, while still green. What do you think I should do. Thanks for your help.
Thank you for following up with the Toronto Master Gardeners on the problem with your Ficus benjamina. It’s very difficult to be sure from your picture but I think your plant might have mealybugs. These are small, pale insects that are related to scales. The adult females cover themselves and their eggs with a white, waxy material that makes them look cottony. Once the nymphs hatch from the eggs and begin to feed, the waxy coating starts to form. Mealybugs are most commonly found on the lower surfaces of leaves and in leaf axils. There is information about strategies for managing mealybugs here.
A few other comments :
Ficus benjamina seem to react to almost any stress by shedding leaves, and in particular this plant has a high intolerance for being moved. So it could very well be that the actions taken to treat your plant have also contributed to your plant’s falling leaves.
There is reference in your original question to the use of potassium carbonate (which is a fertilizer) and in your current question to the use of potassium bicarbonate (which is a fungicide). Based on your photo I don’t think your plant has a fungus. And fertilization should be done when a plant is actively growing, not when it is ailing. So I suggest discontinuing the use of these products.
The most common source of mealybugs is plants newly introduced into your home, so it is important to isolate these for a few weeks.
Please note that the reference to insecticide in the above article applies in the US where this article originates and not in Canada. The use of pesticides in Ontario for cosmetic purposes is strictly controlled by law. This link contains an Allowable list of active ingredients that can be used in Ontario :
https://www.ontario.ca/page/pesticides-home-lawns-and-gardens
I hope this is helpful in your efforts to restore your Ficus benjamina to good health.
Sept 9, 2023