PEACH LEAF CURL - This disease which causes leaf damage and so weakens the tree, is limited to a few Prunus species (including Hawthorn - a popular bonsai species).

Signs are reddish brown blisters on leaves which grow bigger and turn white whereupon the leaves distort, discolour and drop off. The fungus can survive over winter in the bark and bud scales.

Treatment is application of a copper fungiside spray before bud break and again just before leaf fall.