I have a large arrangement of Buxus shrubs that appear to be continually deteriorating after the frost. The leaves are turning yellow/brown and are extremely dry. I have been watering and waiting to see if there is any recovery but the problem seems to be spreading further up through the plants from the roots. Is there anything I can do or any treatment I can give them. I would hate to loose them as the collection would be very difficult and very expensive to replace.
If these are new plants, they may not have settled in. Over-watering will not help. Heavy watering once a week until there is new growth is enough.
If these are established plants, the problem is likely to be box blight or dieback.
Box blight and the similar box dieback are both damaging fungal diseases of box hedging and can affect plants of any age, and are usually worst on clipped plants. Watering would help the fungus.
Liquid copper fungicide may give some control and Rose clear will help too, sprayed on the new foliage as it emerges. A spray in spring and after clipping should help but may not give complete control.