A horticultural dormant oil applied before bud break (flowers, obviously) in the spring. Use of dormant oils are permitted and won't (shouldn't) contravene any pesticide bylaws. Call a few upscale nurseries, the botanical garden, or Google. Here is a link that might be useful: Montreal Gazette spring article

You will have to spray the foliage and limbs with Horticultural oils, Insecticidal soap or one of the Brand named insecticides that contain one of the following ingredients: Permethrin, Acephate, Cyfluthrin or Imidacloprid. The first 2 are the most common ones used in insecticides. Follow labeled directions carefully and apply on a calm day (no wind). Early morning would be best. Check weather forecast to see if rain is predicted. Would also suggest wearing long pants, a long sleeve shirt, leather gloves, tight fitting goggles and a mask when using any insecticides! I don't believe in taking chances when using chemicals! MHO Good luck! Rb

Thanks, I looked at more pictures of other kinds of scale, and I guess this is the nymph stage of one of them. There are not so many of them. I found about a dozen on several of the younger branches, but of course I don't want them to spread. Is hand-picking adequate? I do have some horticultural oil I could spray as well, though I'm not sure when is the right time to do this. I think the cause of stress might be that this tree is planted a bit too close to a black walnut, and I fear the juglone might not be doing it any good. Both trees are too large to move, so I don't think there's much I can do on that score. But any advice is welcomed! Thanks again.

The tree is about 6 feet, it was potted when arrived. Sorry for creating confusion. By saying "just planted" i meant in the spring. I actually planted it in april. Before that it was inside in the original pot for a fee weeks. It was dormant when arrived. I planted it instead of an old big crape myrtle that had been removed a month prior to planting. The soil was clay-ish mixed with the chips from the crape myrtle stump, so I had to remove a lot of soil and mix some existing soil with the top soil. No fertilizer. Bark mulch. Watered 2-3 times a week about half gallon. It is pretty hot here in nc these days. I noticed a few times the leaves started to look drying out so I increased the watering frequency. But at the same time cannot water it too much as I am afraid of the root rot. I do think it may be aphid but what about the dark spots? What is the best way to treat both? And should I change anything in the overall watering/treatment?