We have a grouping of 4 boxwood on each side of the north facing front door...
We have a grouping of 4 boxwood on each side of the north facing front door in Catonsville, Baltimore County. One is showing disease. In April 2014 some webs glistened a bit in the rain. By June 1 there was some webbing around individual branches and dead bits of dark brown leaves and soil was evident under the webbing.Now some areas are bare and some are showing yellowed leaves.It is a very shady area. I have always pruned the boxwood by just snipping off the tops to keep bushes level around the 4th of July each year. I have not witnessed any voles but 10-15 years ago we did have some vole action with soft ground elsewhere in the yard. Our yard has many spiders.The house perimeter and/or problem spots such as the deck in the back yard is treated by Terminix 4 times per year for the last 22 years. I will attach photos of the diseased bush alongside a healthy one. We have had some lower branch breakage from the winter snow and have not known how to fix(tie it up, removal, etc) next to it.
Spiders and their webbing are common this time of year. In general they are predators and help keep pest insects in check. No control is necessary. See our spider publication http://extension.umd.edu/sites/default/files/_images/programs/hgic/Publications/HG9_Spiders_in_Maryl...
Make sure mulch is no thicker than two inches and keep away from the base of the shrubs. Voles do like to use thick mulch as a cover. In general, shrubs will grow much slower in the shade and thin out.
The browning of the branches looks like volutella, a fungal disease.
At this point, all you can do is prune out the affected portions. Remove all old diseased leaves in the shrub and on the ground. Proper pruning includes thinning. Boxwoods have growth buds all along the stem. Hopefully, the plant should put out new growth next season. Monitor the plant throughout the growing season for additional symptoms. See our boxwood publication for more information. http://extension.umd.edu/sites/default/files/_images/programs/hgic/Publications/HG52_IPM_Boxwood.pdf