Blister blight

Causal Agent: Exobasidium vexans is a fungus that causes leaf and flower gall in various stone fruit trees, especially affecting peaches and nectarines.

Symptoms:

1. Leaf Galls:

   • The development of abnormal, fleshy galls on the upper surfaces of leaves. Galls are initially green, turning red or pink as they mature.

2. Flower Galls:

   • Galls may also form on flowers, affecting their normal development.

3. Deformation:

   • Affected leaves and flowers may become distorted and exhibit an abnormal appearance.

4. Reddish Discoloration:

   • Galls often have a characteristic reddish or pinkish discoloration.

Identification:

1. Fleshy Galls:

   • Identification is based on the presence of fleshy galls on leaves and flowers.

2. Color Changes:

   • Color changes from green to red or pink as the galls mature.

Conditions Favoring Disease:

1. Humid Conditions:

   • Optimal Growth: The fungus thrives in humid conditions.

2. Moderate Temperatures:

   • Optimal Growth Conditions: Moderate temperatures contribute to the development of the disease.

Management:

1. Fungicides:

   • Application of fungicides, especially during the early stages of leaf and flower development, can help manage the disease.

2. Pruning:

   • Pruning and removing infected plant parts can reduce the source of inoculum.

3. Cultural Practices:

   • Good orchard hygiene, including the removal of fallen leaves and debris, can help minimize disease spread.

Note: Exobasidium vexans can impact fruit production and overall tree health, and management strategies are aimed at preventing and controlling the development of galls. Timely applications of fungicides, cultural practices, and proper orchard management are essential components of disease control.