My benjamina tree developed white wax like spots on the leaf stem, near the junction where the leaf meets the branch. It started shedding leaves so I put it outdoors, gave it a serious hair cut, hosed it down and sprayed it with a solution of Potassium Carbonate. That was a week ago. It’s still alive, but the was bubbles spots are still there and it’s shedding lots of leaves.
Thank you for contacting the Toronto Master Gardeners.
Ficus benjamina make a wonderful addition to any home but they are prone to a few pest insects such as – Scale, Aphids, Mealybugs, Spider mites, Thrips and Whitefly.
From your description, of waxy white insects, I suspect your tree has scale but if you look online for pictures of the above listed pests, you will be able to compare your own tree with pictures of each to make a definitive diagnosis.
Once you have determined the insect pest, a visit to your local nursery or garden centre would be the ideal place to get the appropriate treatment. Follow the package instructions carefully and repeat the treatment a week to 10 days after the first treatment.
Move the tree away from any other of your houseplants as you don’t want the insect infestation to spread to other susceptible plants
I would hesitate cutting away any more branches or twigs as this may further stress the plant so opt for treatment rather than another hair cut.
Of note, there are other reasons for leaf drop with this particular plant, such as – location movement, recent repotting, pot bound/girdling, over-watering, under-watering, low light conditions, lack of Nitrogen (N), frequent temperature/environmental changes from heating, AC, humidity or draughts.
Going forward, sorting out the insect pest issue and a little TLC rather than dramatic changes and your plant should not only survive but thrive.
Hope this information is helpful.