Question
Dear John, My 3 yr old victoria plum tree,s leaves are
curling in from the edges,they look as if singed,I have
uncurled several,and there is a greyish damp powder not
unlike wet cigarette ash.the young fruits are about pea size just now. hope you can advise, kind regards Brian

Answer
Hi Brian,

What you describe sounds like a very common disease, Peach Leaf Curl caused by the fungi in the genus _Taphrina_.  The diseases caused by these fungi are not lethal to peach or plum unless the infestation is very severe and long term.

Peach leaf curl and plum pocket can be controlled effectively with a single application of an appropriate fungicide. The timing of the fungicide spray is extremely important. The fungicide should be applied as a dormant spray, either in the fall after leaf drop or in late winter before buds begin to swell. Use ferbam, chlorothalonil (Daconil), Bordeaux, or liquid lime sulfur. These diseases cannot be controlled once the leaves have started to expand.

If a dormant spray has been neglected, and disease develops on peaches or plums, maintain tree vigor. Fruits should be thinned heavily to reduce the nutrient drain on the already weakened tree. Trees should be fertilized in the spring to promote new leaf growth and watered frequently throughout the growing season. Do not over-fertilize or fertilize late in the season. This will stimulate succulent growth, which is very susceptible to winter injury.