Filbert Bud Mite 

Scientific Name: Phytocoptella avellanae

Symptoms, Life-cycle and pest management

The filbert bud mite is a very small eriophyid mite that feeds on and within leaf and flower buds and catkins (male flowers)  Feeding causes buds to swell to larger than normal size (hence the nickname “big bud mite”), and infested buds do not produce nuts. Cecidophyopsis vermiformis is another eriophyid mite also found in hazelnut orchards. Cecidophyopsis vermiformis feed in the enlarged buds created by the filbert bud mite; while their feeding does not cause big bud symptoms, it does cause further damage to the bud and, subsequently, yield loss.  Mite activity can be monitored by placing a sticky substance (Tanglefoot or sticky tape) on twigs above and below buds that have evidence of mite infestation. Best control is achieved by applying treatments in the early spring when adult mites become active and are moving about the tree.

The big bud mite (also known as filbert bud mite and hazelnut gall mite), Phytoptus avellanae, is known to be a problem in most of the major hazelnut production areas around the world. This mite has long been associated with the formation of excessive large buds in hazelnuts.

Specific plant damage is indicated by enlarged buds whereby infested terminal buds become swollen and deformed. Bud deformation also occurs in which the development of leaves, blossoms and fruits are affected.

Big bud mite infestation first becomes obvious during late summer and early autumn. Affected buds become spherical and swell to several times their normal size, reaching about 10 mm in diameter. These buds are prone to desiccation and fall from the tree prematurely). The big bud mite can affect both the vegetative and flower buds of hazelnut trees.

Big bud mites living within buds are protected from adverse conditions during the cold months of winter. However, they are subject to desiccation by warm, dry air when they start to migrate to new leaf buds during spring.