Has anyone here had the same issue? Did dormant oil clear it up? I try to avoid sprays in general but I can apply dormant oil after winter pruning, and again before bloom. I assume they are not killed during winter freeze.
If it’s a pump sprayer, it will be the operator doing the work. Spray when the wind is still and it’s just a matter of how much time you spend doing it as far as coverage. In spite of what the literature says about older trees being harder because of fissures in old bark, the scale is mostly in the smaller, smooth branches.
Scale is more of a problem in commercial orchards because their sprays often eliminate scale predators.
I used to have a site with very old trees that frequently had scale pop up and I was able to control it by adding oil to my petal fall and subsequent spray 10-14 days later, back when I used Imidan, which isn’t effective against scale. The oil took care of it.
I do use a handgun sprayer powered by a 4 hp 4 stroke motor, so it wasn’t hard for me to get thorough coverage. By commercial standards that’s a small sprayer but when the gun is fully open it still sprays with about 200 PSI.