Peach leaf curl

Taphrina spp.

1. Identification

Taphrina spp. is a group of fungi responsible for various deforming diseases in fruit trees and ornamentals, including the well-known “leaf curl” or “blister” in several species, a symptomatology globally referred to as "Leaf curl". The diseases caused by Taphrina spp. mainly affect leaves, flowers and fruits, causing characteristic deformations.

2. Causal agent

Ascomycete fungi of the genus Taphrina, described by Fries, which develop between the epidermal cells, causing hyperplasia and hypertrophy of the tissues.
The most relevant species include:

• Taphrina deformans (peach leaf curl or blister)
• Taphrina pruni (deformed fruits in plum trees)
• Taphrina cerasi (diseases in cherry trees)
• Taphrina betulina (diseases in birch)

3. Main hosts

• Stone fruits: peach tree, plum tree, cherry tree
• Ornamental broadleaf trees: birch, oak, alder
• Other susceptible species depending on the species of Taphrina
  Each species of Taphrina tends to be relatively host-specific.

4. Symptoms

• Leaf deformations (thickening, undulation, blisters)
• Colour changes: light green, yellow or reddish
• Thickening and brittleness of the leaves
• Fruit deformations (elongated or twisted fruits)
• Premature drop of leaves and fruits in severe infections
• In some species, formation of a whitish film of spores on the surface

5. Disease cycle

• The fungus overwinters on the surface of the branches and buds.
• Infection occurs in spring, during budbreak, when the young leaves are highly susceptible.
• The fungus penetrates directly into the young tissues, developing between the cells.
• After sporulation, the infected tissues dry out and fall, releasing the fungus for new cycles.
• The disease is favoured by humid springs and mild temperatures.

6. Favourable conditions

• High humidity during budbreak
• Moderate temperatures (10–20 °C)
• Frequent rain in spring
• Vigorous trees but with very tender buds at the start of the season
• Lack of aeration in the canopy

7. Disease management

• Preventive treatments at the end of winter or beginning of spring, when authorised
• Removal of deformed leaves and fruits to reduce inoculum
• Aeration pruning to improve air circulation
• Avoid sprinkler irrigation during budbreak
• Use of less susceptible varieties, when available
• Annual monitoring, given that the disease manifests itself mainly at the start of the season

Bibliographic references

• Agrios, G. N. (2005). Plant Pathology. Elsevier.
• EPPO. Diagnostic Protocols for Taphrina spp.
• FAO. Guidelines for Integrated Management of Fungal Diseases in Fruit Crops.
• European Commission. IPM Principles for Stone Fruit and Ornamental Trees.