I have used WiltPruf for many years on broad leafed rhododendrons and have always found it helpful in bringing them through the winter in better condition than they would have been without it. Last winter's conditions in New England were extreme: deep cold, high winds, and lots of snow that intensified sunlight. Anything you can do to protect shrubs from wind and sun this winter - burlap barriers, evergreen boughs, anti-desicants - is worthwhile, especially if you experienced droughty periods this past summer and fall. Many shrubs were weakened last winter and did not make a full recovery over the summer. Making sure shrubs are well watered before winter really sets in is also important. Anti-desiccants can be sprayed any time the temperature is above freezing and will remain so long enough for it to dry. After Thanksgiving but before Christmas is a good rule of thumb. Even though a second spraying in March is advocated for many products, one in late fall has always worked fine for me.

same thing i said here... which was a few posts down from yours

ken

http://forums2.gardenweb.com/discussions/3509026/green-mountain-boxwood-winter-protection?n=3

I'd also look into boxwood blight-make sure that's not a part of what you're seeing. I believe that relatively new pathogen has been identified from your state.

+oM