Hazelnut bud mite

The hazelnut bud mite (Phytoptus avellanae) is a microscopic pest belonging to the family Eriophyidae. These tiny arachnids are invisible to the naked eye but can cause significant economic losses in hazelnut orchards worldwide due to their specific feeding behavior inside the developing buds of the trees.

The host plants for this pest include primarily Corylus avellana (common hazel) and its cultivated varieties (filberts). The mites infest both vegetative and reproductive buds, but the damage to flower buds is particularly destructive, directly impacting the nut production of the season.

The life cycle of the hazelnut bud mite is synchronized with the phenology of the host plant. The adults overwinter inside the infested buds. As the temperature rises in spring, the mites migrate to newly forming buds to feed and lay eggs. Throughout the summer, the population reproduces rapidly, moving across branches to infect new buds.

The most distinctive symptom of infestation is the formation of enlarged, spherical, galled buds, often referred to as «big bud». These malformed buds remain closed, fail to develop normal shoots or flowers, and eventually dry out. This reduces the vigor of the tree and leads to a decline in overall crop yields over time.

Effective management requires an integrated pest management (IPM) approach to keep populations below the economic injury level:

• Pruning and removing infested branches to reduce the initial source of infestation in early spring.
• Applying recommended acaricides during the peak migration period, which usually coincides with the bud-burst phase.
• Monitoring the orchard regularly to detect the first signs of the «big bud» symptoms on branches.