Blackberry psyllid, (Trioza tripunctata), causes severe curling on both thornless and thorny blackberries. Psyllid damage is often mistaken for a plant disease since the curling continues for some time after the insects are gone.
Psyllid damage is only a problem when blackberries are grown in close proximity to conifers, which serve as an overwintering site for adults.
More information:
- Blackberry Psyllid – (Virginia Tech)
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