Blackcurrant gall mite

The blackcurrant gall mite (Cecidophyopsis selachodon) is a microscopic pest belonging to the Eriophyidae family. It is an extremely small organism, approximately 0.2 mm in length, which makes it nearly impossible to spot without the aid of a microscope.

These mites possess a worm-like, elongated body that is typically creamy or white in color. They are characterized by having only two pairs of legs, which are located at the front of the body.

The entire life cycle occurs within the buds of the host plant. They thrive in the protected environment inside the buds, feeding on the developing plant tissues throughout most of the year.

Dispersal usually occurs during the spring when the buds begin to open, allowing the mites to emerge and spread to new buds or neighboring plants via wind and insects.

The population density can increase significantly under favorable weather conditions, particularly during mild winters and wet springs, leading to massive infestations.

The primary host for this pest is the blackcurrant (Ribes nigrum). While redcurrants and gooseberries are less frequently infested, they can also serve as hosts for the mite.

The mites feed by piercing the plant tissues, which causes the internal structure of the buds to become disrupted and eventually kills the developing leaves and flowers.

This feeding activity results in significant yield losses, as the infested buds fail to produce fruit or, in severe cases, die off completely before opening.

A critical threat associated with this pest is its ability to transmit the "reversion" virus, which causes systemic infection and renders the currant bush sterile.

Infested bushes eventually show signs of stunted growth, poor vigor, and an overall decline in health, often making the plant unproductive within a few seasons.

The most distinctive sign of an infestation is the presence of "big buds." These are swollen, rounded, and abnormally shaped buds that resemble miniature cabbages.

During the spring, these infested buds often remain dormant or produce deformed, chlorotic leaves that fail to grow properly and dry out prematurely.

Early stages of infestation can be difficult to detect, requiring a close inspection of the bushes during the winter or early spring before the buds break.

Symptoms of the reversion virus, which is spread by the mite, include elongated, narrow leaves with fewer veins and a lack of the characteristic blackcurrant scent.

A noticeable decrease in berry production and uneven ripening across the bush are reliable indicators that the mite population has become established.

The primary control method involves hand-picking and destroying all swollen "big buds" during the late winter or early spring, strictly before the mites begin to migrate.

Severely infested branches should be pruned out and burned to reduce the overall mite load. In cases of extreme infestation, it is advisable to remove the entire bush.

Preventive measures include planting only certified, mite-free nursery stock to ensure that the infestation is not introduced to a new growing site.

Chemical control using specific acaricides can be effective, but applications must be timed precisely with the period of mite migration to maximize impact.

• Maintaining plant vigor through balanced fertilization and proper irrigation.
• Establishing spatial separation between new plantations and older, potentially infested bushes.