My mandarin orange tree is losing leaves one by one....the rest look healthy for now. They dry up after looking limp for a while. There are also spots down the spines of all the leaves and on the branches bit they have always been there....they come off If I wash or pick them off. Any help???
It sounds like the tree has an infestation of scale. The 'spots' or bumps would be the adults. Is there a sticky substance on the foliage and under the tree?
I use insecticidal soap for scale but it requires multiple applications (repeated every 7-10 days) and perseverance. Also it is ineffective against the adults so they have to be removed by hand before spraying. I've not used it before but horticultural oil is reportedly more effective.
