I'm new to Bonsai and recently got a Chinese Juniper. I live in the tropics and I keep the plant on my outdoor balcony, with it getting a good few hours of direct morning / noon sunshine. I water the roots and mist every day. I had rarely applied insecticide.
About 3 weeks ago I noticed white powdery flakes on the leaves and, on one of the lower twigs beneath a leaf pad, it was almost a hard crust. Some insecticide (bottle label read synthetic pyrethoid) and selective pruning at the bonsai nursery got rid of them after a few days.
Now, the white powdery flakes seem to have come back, although in lesser amounts. I attach a few pictures here and would be grateful if someone could tell me if this is indeed scale insect or something else. I had read that Junipers may produce a natural resin that forms white flakes like this.
The plant seems otherwise healthy to my untrained eyes, with light green growing tips and little evidence of other stress such as browning tips or excessive needle foliage.
Should I be worried, or just keep up my daily care regime, apply some insecticide and wait for it to go away ?
As I'm new to this, any comments would be most welcome!