I have a number of old boxwood that have developed in some of the more exposed to sunlight a orange discoloration which soon becomes brown and white and dead within several weeks. I have tried a fungicide , OTC, but that is not helping. This mostly occurs slowly in the areas of the plant facing the sun E to S. It looks like sun scald in the beginning on the tips of the plants but soon spreads to other branches. The plants get good drainage and are watered as needed.
It is not recommended to spray a fungicide unless you have identified the problem and know what you are spraying for. Boxwoods in general can be susceptible to several fungal diseases, insect, and abiotic issues (cultural and environmental). Please send us photos of the affected boxwoods. Send photos of the whole shrub and affected branches and stems so we can see what you are dealing with. Look at our publication for information on symptoms and causes