My viburnum hedge is dying, the leaves are going fawny gray with little black dots over them. I have used an aphid and mite spray and sprayed them 4 weeks in a row to no effect. Any new leaves look wilted and curling up. Normally they would be in flower now. Is this aphids?
It is possible from your description that your viburnum hedge has been heavily infected by thrips during the past summer. Thrips are a very very small insect that attack many plants en masse. While spraying can kill the thrips, the symptoms will remain on your leaf until they fall and are replaced in the growing season.
The symptoms of thrips are visible on the upper side of a leaf by a grey silvery colouring, while on the underside of the leaf, a brown and sometimes sticky appearance is very obvious.
While viburnum can make an attractive hedge, in the short to medium term, as the plants reach an age of 10 years and more, they tend to become woody and the leaves often smaller and stunted in appearance.
To extend the life of your viburnum hedge, regular clipping over the summer months as well as fertilising with a garden fertiliser and deep watering when extended dry spells are experienced, will all help maintain your hedge in healthy condition.
If your hedge appears in poor condition it may well be advisable to replant with another species that may be more suitable for your specific conditions. Your local garden centre can help with your selection.