A friend has a Rock Daphne which bloomed profusely this spring. When I stopped by to see her today, all the leaves were withered and falling off. The shrub is in an area with ample shade, receives proper watering several times a week. I did notice the limbs of the shrub had a lot of small black nodes throughout the entire shrub. Is it possible this is some kind of scale? Any of possible culprits? Possible solutions? Thank you.
It sounds like a pest of some kind or even a fungus is attacking the shrub. I would try treating it with Neem oil spray, which will help with both insect pests and fungus. Here is more information: https://www.gardeningknowhow.com/problems/pests/neem-oil-uses.htm