My 4 Boxwood shrubs are infected. Some have lost all leaves. Others have leaves that are yellosing. Yet others are still green and bushy. Is it worth applying the expensive fungicide I bought. Or should I just call it a day? I haven't found info that tells me that after the application they will rego their leaves and branches.
Can you tell us more about the symptoms you are seeing on your boxwoods? Are the leaves falling off? Do you see black spots on the foliage? Black lines on the stems? If so, these are characteristics of boxwood blight. You can see photos of the symptoms here for comparison. https://extension.umd.edu/sites/extension.umd.edu/files/_docs/programs/ipmnet/Boxwood%20Blight-UnivO...
Boxwood blight is typically brought in on new plants or ones that have been pruned with tools/equipment that were used on boxwoods infected with the blight.
Please send us photos of the boxwoods so we can see what you are dealing with. Send photos of the whole plants, around the base, and affected foliage and
branches. There are other issues that can cause decline. Are your boxwoods in a very wet area? Do they have good drainage? How old are the plants? Boxwood decline can occur as a result of excess water, excessive mulch, soil compaction, deep planting, the addition of soil over the root zone, and root injury from construction. https://extension.umd.edu/hgic/topics/boxwood-decline