HELP! BOX BLIGHT ON THE HORIZON CAUSED BY A NASTY LITTLE CATERPILLAR

Just listened to the latest BBC 4's Gardeners' Question Time and, like some of their regular listeners, we have an attack of box blight caterpillars.  This horrible  disease  has affected our lovely buxus semivirens (box plants to you and me) so that their leaves and stems are looking so sad.  I've discovered that it is caused by the fungus Cylindrocladium buxicola. It appears that there's another type of blight that affects box – Volutella blight – but this does less damage to plants and is easier to control.