Pear leaf blister

The causal agent of this disease is the fungus Taphrina piri, a member of the Taphrinaceae family. It acts as an obligate parasite, disrupting the normal development of pear leaves and young shoots by inducing hyperplasia and hypertrophy of the affected plant cells.

Symptoms include the appearance of thickened, distorted leaves that often show yellow or reddish discolorations. In many cases, infected shoots develop abnormal, cluster-like growth patterns commonly referred to as «witches' brooms,» leading to severe deformation of the canopy structure.

The development of Taphrina piri is strongly favored by cool, wet spring weather conditions. The spores persist in bark crevices or under bud scales during winter, becoming active as soon as the temperature rises and moisture is available during the early budding phase.

The economic impact is significant as the disease reduces the photosynthetic capacity of the tree. This weakening effect not only stunts growth and reduces fruit yield but also lowers the tree's overall vigor, making it more susceptible to environmental stress and other secondary pests.

Preventative and control measures are essential for maintaining healthy orchards:

• Strict removal and destruction of infected twigs and «witches' brooms» to eliminate inoculum.
• Application of copper-based fungicides during the dormant season and at the green bud stage.
• Enhancement of orchard hygiene by removing leaf litter before the new growing season.
• Selection of resistant varieties, if available, and maintenance of optimal tree health through balanced fertilization.