Blackcurrant Gall Mite Emergence Charts

These emergence charts are designed to help you time your control measures.

Using weather data from the MetOffice (DataPoint) and Met Norway, this tool estimates when blackcurrant gall mites are likely to emerge from big buds for 16 key grower locations and 141 locations overall. This tool is based on research carried out by Prof. Jerry Cross at East Malling from 1995-1999 on the varieties Ben Tirran and Ben Lomond.

How to use:

  • Select one or more locations on the map, or select a whole region from the dropdown list

  • To select more than one location, use the Ctrl button

  • The tool is updated daily

  • If you click 'multiple years' you can select different years to compare. Note that the location symbols on the map turn white and no longer indicate emergence progress when ‘Multiple years’ has been selected

  • Hover over the buttons, the locations on the map and the lines in the chart for more info

What to do next:

  • The 100 mark on the graph represents when the first mites will emerge and has shown to be accurate to within three days over the last decade. 
  • You are normally advised to apply control treatments just before the line reaches this mark.
  • When the line transitions to the blue section, it identifies when 50% of the mites have emerged. Growers have generally aimed to apply their second control treatment just ahead of that time.
  • To avoid the possibility of yield losses, applications need to be made by the time the first grape is visible.
  • We recommend you are guided on the exact timing and the choice of control products by a BASIS qualified fruit consultant

Blackcurrant Gall Mites

Primarily a pest of blackcurrants, the gall mites are less than 0.25mm long. They feed and breed within buds causing distinctive bud swelling.

Mites emerge from infected buds in the spring and seek new buds. Infested buds start to swell in summer, but are most obvious in winter.

Reversion virus is carried by mites and substantially reduces cropping.