Do you give them some supplemental watering and light fertilizing with nitrogen in the spring to get them going? If they are drought stressed from too infrequent rains and infertile soils, they will probably respond to the fertilizer with iron and periodic watering when/if it stays dry. As they get more mature and rooted in, they generally are more resistant to drought stressed color changes.

Thanks, Bahia. They were watered regularly during the dry spell, but I will try nitrogen fertilizer in the spring. Maybe they will revive! The site may be just too sunny for them.

Try WSU Cooperative Extension for diagnosis. Multiple circumstances associated with discoloration of box. I walked by some big blocks of various kinds of box (in containers) at a nursery the other day, noticed a section of an Asiatic box was all orange - something I have seen many times before. Especially when such may have been in the same soilless potting medium for months, likely without fertilization since having left the production facility I have to wonder if the problem is often leached, decomposed material around the roots. Most kinds of box may like a limey soil, common box is associated with limestone outcroppings in Britain.

Here is a link that might be useful: Boxwood Questions and Answers

Bboy, thank you for the information and the boxwood link. (My boxwood certainly look just like the boxwood in the picture.) Next spring, I will spread some compost with an addition of lime around the boxwood to see if the color improves.

Meanwhile, I located a WSU extension nearby. If they think it is more serious condition, I may remove all the boxwood to save other shrubs in the area. I have noticed a sarcocca in an adjacent (and shady area) also displaying yellow leaves.

You may also wish to explore this locally generated site.

Here is a link that might be useful: Plant Disease Control

Thank you, Bboy, for the new link. It was interesting to see the two examples of boxwood disease that were pictured. My boxwood did not look exactly like either. So, now I am inclined to go forward with a springtime application of compost with a little extra nitrogen and lime. Maybe the boxwood can be saved after all.

If fertilization is indicated it should be done now, rather than waiting until spring. (A second application could also be made in spring, if it seemed like a good idea). Rather than guessing you could see about sampling your soil and having it analyzed. WSU Cooperative Extension has information about this.