Q What is peach leaf curl?

A This is a serious and spectacular fungal disease of the peach family, which results in severe leaf damage. It affects peaches, almonds and nectarines. It's rare on apricots, or on plants grown under glass. The disease is likely to be most severe during a cold, wet spring.

Caption: Peach leaf curl causes distinctive damage to the leaves of peaches, almonds and nectarines

Q How do I recognise peach leaf curl?

A The symptoms are red blisters and thickened areas on leaves. These then curl, usually downwards, and fall early. The initial pale-green or yellow colour turns bright red or purple, giving way to white and grey as the disease progresses, and ending up brown as the leaves die. New, unaffected foliage is usually produced later in the year. Young shoots, flowers and fruits can also be attacked. Fruits and flowers may fall early, and the twigs become stunted, but seldom distorted.

Occasional attacks don’t do much harm, but if the tree is attacked repeatedly, cropping can decline. Red blisters and thick, curled-up leaves are a sure sign of peach leaf curl, a serious fungal disease that also affects almonds and nectarines.

Q What causes peach leaf curl?

A The fungus Taphrina deformans, which is one of a family of fungi that deforms leaves, flowers and fruits.

Q Can you tell me more about peach leaf curl?

A When the leaves go grey and powdery, spores are being produced. They overwinter on the tree, in the bark, and possibly beneath the scales of the buds. These are washed into the buds in early spring and infect the leaves as they uncurl.

As the fungal strands or mycelium spread through the leaf tissue, they induce the leaves to grow excessively, causing them to enlarge and distort.

Later, the spores produce fungal threads which break through the leaf surface to make a powdery grey, felt-like area. The spores are carried on the breeze and by rain splash to infect new, young leaves. Infection is most rapid when the buds have just opened. Older leaves are less easily infected and warm, dry conditions also reduce infection.

Q How do I control peach leaf curl?

A Hot, dry summers tend to check the development of the disease. Once it gets a hold it is very difficult to control. Pick off badly affected leaves as soon as they are seen, and before they develop a bloom of spores. Bin them to reduce the source of infection for the following year. Make sure the tree has enough food and water to promote healthy new leaves. There are no chemical controls available.

Q Can peach leaf curl be prevented?

A Yes. You can prevent the spores washing into the buds by building a plastic shelter to keep the rain off. Keep this in place from November to mid-May. Make sure the tree is ventilated by leaving the sides of the plastic open and allow the roots to receive water by leaving a gap near the ground. Covering is easiest with wall-trained plants. Pot-grown plants can be brought indoors.

Caption: Bring pot-grown plants indoors from November to mid-May