Raspberry leaf and bud mite
Yellow blotches on the foliage of raspberries can be caused by a tiny sap-sucking mite that lives on the underside of leaves. Despite appearances plants with this mite usually produce a worthwhile crop of fruit.
Latin name Phyllocoptes gracilis
Plants affected Raspberry
Main symptoms Pale yellow blotches on upper leaf surface. Some leaf distortion on upper parts of canes
Caused by A microscopic mite that sucks sap from the underside of the leaves
Timing Late May-September
What is raspberry leaf and bud mite?
Raspberries with leaf and but mite show a number of symptoms;
- From May onwards, pale yellow blotches develop on the upper leaf surface
- On the corresponding places on the underside of leaves, the colour is slightly darker than the usual whitish green
- Affected canes grow to their usual height and produce fruit but leaves at the tops of the canes may be malformed
Note: Some virus infections also cause yellow markings on the foliage, usually accompanied with stunting of the canes and poor fruit production. The mite is a more common problem than virus infections although it can transmit Raspberry leaf blotch virus.
- Raspberry leaf and bud mite can often be tolerated as it does not always affect cropping
- Heavily affected plants that no longer produce a worthwhile crop should be replaced
- Some raspberry cultivars are less susceptible to the mite. Observations on plants grown at Wisley indicate that these include ‘Glen Lyon’, ‘Glen Rosa’, ‘Glen Prosen’, ‘Glen Magna’, ‘Malahat’, ‘Gala’, ‘Tulameen’, ‘Julia’, ‘Rossana’, ‘Leo’, ‘Galante’, ‘Terrie Louise’ and ‘Lauren’
- More susceptible cultivars include ‘Glen Ample’, ‘Glen Shee’, ‘Malling Jewel’ and ‘Malling Enterprise’
- None of the pesticides available to home gardeners will control this mite.
The microscopic raspberry leaf and bud mites overwinter in and around the buds on raspberry canes.
They emerge in late spring and begin feeding by sucking sap from the underside of leaves. This results in yellow blotches developing on the upper surface and slightly darker patches on the lower leaf surface where the mites are active.
The mite population increases during the summer and leaves at the shoot tops may fail to expand to their usual size and shape if the population of mites is large.
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