A patch of my privet hedge appears to be completely dead: all the leaves are brown and withered, and there are no new shoots. It was quite all right last year. What is the matter with it, and will it recover? If not, can I plant some more privet in its place?
When a section of privet hedge turns brown and does not grow, it is usually because it has been infected with a disease called honey fungus .
You should dig up the dead privet completely, with all its roots, together with one or two apparently healthy plants on each side of it, and burn them; then treat the soil with Bray’s Emulsion (which you may also find under its original name, Armillatox). Alternatively, you can remove the soil in which the privet was growing and replace it with fresh soil. You can replant about two years later. This disease can infect all woody plants, and it is a good idea to destroy any dead wood elsewhere in the garden, as this may also be infected.
There is a white woolly substance all over the leaves and stems of my beech hedge. What is it, and how should I deal with it?
Your hedge is infected with beech scale (Ctyptococcus fagisuga), a tiny insect which is covered with white ‘wool’ for protection from predators. It sucks the sap from the foliage and overwinters in its egg form. Spraying under strong pressure with malathion is a useful control; you should also fork the soil lightly around the hedge, and give it a dressing of well-rotted organic matter in autumn.
I have found two of the largest caterpillars I have ever seen feeding on the leaves of my privet hedge. They are about 75 mm (3 in) long, green with red stripes on the sides, with a short erect tail at the end. What are they, and should I spray the hedge?
These are the larvae of the privet hawk-moth, a night-flying species with a wing span of 100 mm (4 in) and brown in colour. The caterpillars are rarely seen nowadays and do little damage; there is no need for control measures.