Hi all, we have four mature boxwoods in four different spots in the yard. All are infested with white cottony looking stuff growing along the stems between the leaves. If you shake the stems it falls to the ground. I noticed today, swarms of flies all around the plants. I don't know if the flies are related to the white stuff or not. Any help on what I can/should spray them with so I don't lose them. The leaves are turning brown in the middle of the plant, so clearly this if affecting them.

Any help would be greatly appreciated!

Laura