Shot hole

Stigmina carpophila

Stigmina carpophila:

Stigmina carpophila is a fungal pathogen that causes a disease known as "shot hole," affecting various stone fruit trees. The term "shot hole" refers to the characteristic appearance of the lesions on infected leaves, resembling small shot holes. Peach trees (Prunus persica) are particularly susceptible to this pathogen. Here's an informative description:

Symptoms:

  1. Shot Holes: Circular lesions on leaves that give the appearance of being shot with a shotgun, with holes in the center and a dark border.
  2. Fruit Lesions: In addition to leaves, the pathogen can also cause lesions on fruits, which may lead to fruit drop or reduced quality.
  3. Leaf Yellowing: Yellowing of the tissue surrounding the lesions, leading to premature defoliation in severe cases.

Identification:

  1. Characteristic Lesions: Identify circular lesions with a central hole, surrounded by a dark border on leaves and fruits.
  2. Distribution: Lesions are often distributed across the affected leaves, giving them a distinctive appearance.

Disease Cycle:

  1. Overwintering: The pathogen can overwinter in infected plant debris or on the tree itself.
  2. Spore Production: Spores are produced in infected tissue during periods of favorable conditions.
  3. Infection: Spores are spread to new leaves and fruits, initiating new infections.

Management:

Cultural Practices:

  1. Sanitation: Remove and destroy infected leaves and debris during the growing season and in the fall to reduce overwintering sources.
  2. Pruning: Proper pruning to improve air circulation can help reduce humidity and minimize disease development.
  3. Resistant Varieties: Planting resistant peach varieties, if available, can be an effective strategy.

Fungicide Application:

  1. Foliar Fungicides: Application of fungicides, especially during critical growth stages, can help manage shot hole disease.

Regular Monitoring:

  1. Scouting for Symptoms: Regularly monitor peach trees for early symptoms of shot hole disease, especially during periods conducive to disease development.

Weather Considerations:

  1. Avoid Overhead Irrigation: Minimize leaf wetness by using drip irrigation or watering at the base of plants to create less favorable conditions for disease development.