Aphids? Pine Scale?
About three weeks ago, I had black powdery stuff on my 25 year-old euonymus hedge and sprayed neem oil three times over about a week and a half. (Was told the problem is aphids.) The problem is improving and I see a decrease in black areas, along with new growth. Now I have a visibly deceased one-year-old rosemary plant with white-ish areas AND white spots on my newly planted row of dwarf Japanese Holly shrubs and my pair of newly planted Golden Ticket shrubs. The white spots have just appeared on a potted Butterfly Bush. (Was told they might be pine scale.) I read about pine needle scale the Missouri Botanical Gardens article and am not sure how to proceed. Seems they recommend both neem oil and dormant oil and have purchased both. Should I use either or both of these products? Also, can I use the same sprayer for both? Many thanks! Note: A few hours after I wrote this my potted lamium had the bug on it. The plant was untouched earlier in the day. This time, the insect was clearly visible.
Montgomery County Maryland
The 25 year old euonymus sounds like it was subject to a scale insect and there are several types. In general, euonymus are susceptible to euonymus scale and cottony camellia scale.
Euonymus scale is an armored scale that does not exude a honeydew and growth of a black sooty mold. It is possible it is an old overwintered scale.
Here is our web page for photos and control https://extension.umd.edu/hgic/topics/euonymus-scale-shrubs
Euonymus can also be susceptible to cottony camellia scale. This is a soft scale that exudes honeydew and promotes the growth of a black sooty mold. Here is our webpage for photos and control https://extension.umd.edu/hgic/topics/cottony-camellia-scale-shrubs
You can monitor the plant this growing season and send us photos if you see
Rosemary - this looks like old insect damage from last year, possibly thrips, a sucking insect. At this point remove any dead stems and leaves. You may have to start over with new plants.
Left and right photo - looks like it may be possible bird poop on the foliage.
You can send us photos of the white spots on the butterfly bush and the other shrubs. This does not sound like pine scale.