The drastic leaf shed suggests Boxwood Blight infection, though we can't see detail of the leaves and stems to see if the characteristic blackened lesions are present as confirmation. You can use the information on our boxwood diagnostic page to see if this or other common ailments (like Volutella Blight, our other primary suspect) are likely responsible for the defoliation. It is possible that more than one pest or disease (likely the latter in this case) is overlapping and present at the same time.

There is no cure for existing disease, as fungicides cannot reverse their damage, and for shrubs that have lost lots of growth, replacement is the more practical approach. If you prefer to keep boxwoods in this location, look for modern cultivars with improved resistance to Boxwood Blight and Boxwood Leafminer, the two more damaging and prevalent (respectively) conditions for boxwoods in our region. No cultivar is immune to all potential problems, but at least several are on the market these days with good resistance. Ideally, the plants would be replaced with a species other than boxwood, since very few boxwood ailments would affect other species of shrub. If you do grow boxwoods again, avoid shearing them as this pruning practice makes them more vulnerable to pest and disease outbreaks. (The pruning shears can also move infectious spores from one shrub to another, though this risk is not unique to boxwood or its pathogens.)

Miri

Thank you for your response.