Peach Leaf Curl

Causal Organism:

• Taphrina deformans
• Sub-division: Ascomycotina

Symptoms:

• Affected Parts: Leaf, green twigs, shoots, and fruits.
• On Leaf:
  • Leaves become thick, puckered, and severely distorted.
  • Thickened areas turn yellowish, then grayish-white.
  • Severe infection leads to leaf drop, reducing tree growth and fruit production.
• On Shoot:
  • Affected shoots become thickened, stunted, and distorted.
  • Severely infected shoots may die.
• On Fruit:
  • Distorted areas develop on fruit surfaces.
  • Later in the season, these areas become corky and may crack.

Etiology:

• Causal Agent: Taphrina deformans is an ascomycete fungus.
• Mode of Infection:
  • The fungus infects young leaves as they emerge from buds.
  • The pathogen grows between the leaf cells, causing abnormal development and distortion.
  • It produces a layer of ascospores on the surface of infected leaves, giving them a powdery appearance.

Disease Cycle:

• Primary Infection:
  • Ascospores are the primary inoculum.
  • These overwinter on tree surfaces, bud scales, and bark.
  • During favorable conditions, ascospores germinate and infect emerging leaves.
• Secondary Infection:
  • Conidia serve as secondary inoculum.
  • These are produced on infected tissues and can spread to other parts of the tree.

Favorable Conditions:

• Low temperatures and high humidity promote disease development.
• Cool, wet weather during bud break is especially conducive to infection.

Management:

1. Cultural Practices:
   • Sanitation: Remove and destroy infected leaves and twigs to reduce inoculum levels.
   • Pruning: Prune trees to improve air circulation and reduce humidity around leaves.
2. Chemical Control:
   • Copper Oxychloride Spray:
     • Apply at 0.3% concentration.
     • Best applied during the dormant season before bud break.
     • A single thorough application is usually effective in preventing the disease.
3. Resistant Varieties: Planting resistant peach varieties can reduce the risk of infection.