Answer: Unfortunately, based on your description I am not certain what is affecting your plant. It may be a scale insect infestation as that is a fairly common problem with this shrub. Here are some photos. You may need to cut and paste the complete url into your browser to make it work correctly.
It can quickly spread to nearby shrubs so it is important to try to control it. This can be treated with horticultural oil or commercially formulated insecticidal soap applied per the label directions. Be very thorough in applying the spray so it contacts all surfaces of the plant including the underesides of leaves and the stems. A winter application of dormant oil is also usually needed to achieve control.
In addition, prune out the worst affected branches. Remove any affected leaves and dead stems and dispose of them in the trash to limit sources of reinfection; do a thorough clean up around the plant in the fall and early spring for the same reason.
Finally, be sure to water during dry spells to help reduce overall stress on the plant.
You may also want to consult with your local county extension and/or a professionally trained nurseryman for a more specific diagnosis and based on knowing that with more certainty, determine how to proceed.
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