Peach leaf curl
Note Number: AG0160
Published: December 1999
Updated: August 2010
Leaf curl, caused by the fungus Taphrina deformans, is mainly a disease of peaches and nectarines, although it may also affect almonds and apricots. The disease occurs wherever peaches and nectarines are grown, and if not controlled can seriously weaken trees.
In spring infected new leaves are thickened, curled and distorted. They are pale-green at first, but soon show red or purple colours and become conspicuous. Often the entire leaf is affected, but sometimes, especially with late infections, only small patches of the leaf are affected (Figure 1 and 2). Infected fruit show raised, irregular rough patches that are often red in colour. Such fruit often falls prematurely. Later the colour fades as the fungus begins to produce masses of powdery grey spores on the upper surface of the leaf. The diseased tissue dies and leaves may fall soon after the spores are produced. However, the tree usually produces new leaves that remain healthy as the season advances. If cool, wet weather persists during spring, infections may continue to appear on new leaves for several months. Infected shoots are thickened, distorted and yellow-green in colour. Heavily infected shoots may be killed.
If uncontrolled, leaf curl is most destructive. It may destroy the new leaves in spring, cause shoot dieback and loss of crop. If unchecked over several years, the disease may gradually weaken the tree until it dies.
Cool, wet conditions during leaf emergence in spring favour the development of leaf curl. Continued cool, wet weather favours further cycles of the disease. Disease development is stopped by high summer temperatures and the fungus survives summer as ascospores. These germinate in autumn rains and form yeast-like spores that can overwinter in bud-scales and on twigs. These spores then infect the newly developing leaves that are produced from such buds in spring.
Leaf curl can usually be controlled satisfactorily by one spray of a suitable registered fungicide at any stage of dormancy. Most effective control is achieved by spraying when the buds are swelling but before they have opened. It is not possible to control the fungus once it has entered the leaf. Poor disease control is usually a result of spraying too late; that is, after budswell. In a planting containing peach and nectarine cultivars, sprays must be timed for that cultivar which shows the earliest movement of buds.
Where the disease has been difficult to control in previous seasons, a program of three sprays is recommended. The first spray should be applied in autumn, at leaf fall. The second spray should be applied immediately before budswell at the late dormant stage, and the third spray about one week later at budswell.
Some cultivars show resistance to leaf curl, but apparent resistance observed in the field may be due to different times of bud movement which may avoid favourable conditions in one season, only to become infected in another season following different weather conditions.
Contacts/services available from DEPI
For effective pest and disease control, correct diagnosis is essential. Phone Crop Health Services on (03) 9032 7515 or fax (03) 9032 7604
This Agriculture Note was first published in December 1999 and it was most recently reviewed by W.S. Washington, Plant Standards in August 2010.
Published and Authorised by:
Department of Environment and Primary Industries
1 Spring Street
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