Hi, 

The file format that the photos came in as is too small to examine closely but the dieback might be Volutella disease or root-related (vole damage? you can look under the branches around the base for chewing marks) which can be common issues with boxwood.  The current drought isn't helping with symptoms but probably also isn't the sole factor. You can explore our boxwood diagnostic page and this can help examine symptoms to see what matches the typical ailments described on the web resource. 

The yellow spots might be leafminer damage. If you suspect leafminer, you can follow the management for it on our leafminer webpage.

You can prune out the dead branches and make sure the plants are watered sufficiently with the drought like conditions that are still through most of the state. You can also do some pruning to open up the plants rejuvenate growth. Boxwood can mostly be pruned any time of year but the end of summer and beginning of fall they are hardening off summer growth to get ready for cold winter months. Pruning then would cause the plant to put out new growth which could get damaged by winter cold. You can prune again once the plant has gone into a dormant state later into November.  You can refer to the Virginia Tech Extension Shrub Pruning chart for best pruning times.

Feel free to come back to us with different photos or if you suspect other symptoms. 

Emily