Question: We have a mature peach tree which has been in our garden for some years. Last year we had large, fragrant fruit - but they were all starchy and inedible. Also this year it's got curling leaves - will these permanently damage the tree? We would hate to lose it. And is it ever going to be possible to get edible fruits from our tree?
R. Reynolds, Muswell Hill
Answer: A large outdoor peach tree whose fruit failed to ripen suggests a tree grown from a stone. These are quite common and often in warm areas, such as big cities, can produce tasty ripe fruit in especially hot summers. You could try bringing them indoors to ripen in autumn.
The usual cause of curling peach leaves is a fungus called peach leaf curl. Here the leaves go red, thicken and are often covered with a white bloom of fungal spores. Your description does not quite fit this disease and in any case I would have expected it to strike before now if it is common in your area.
Another cause is aphids or greenflies - there is one called peach-leaf roll aphid. These insects suck sap from the plant, commonly on the underside of leaves, and secrete chemicals that cause the leaf to curl up presumably sheltering the aphid from its enemies and perhaps enhancing sap flow to help the insects feed. To check if this is your problem look for tiny greenfly under the leaves.
I expect your tree may be too big to spray but you could try applying copper fungicide (Vitax Bordeaux Mixture, Fruit and Vegetable Disease Control) in autumn and a further two applications in January and February (a fortnight apart).
There are no synthetic insecticides licensed for use on peaches in Britain and other more ‘natural’ ones will not be able to penetrate the distorted leaves. Therefore you are unlikely to eliminate these pests now, but in future years catch them before the leaves open, with insecticides based on plant materials such as Py Spray Garden Insect Killer.
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