Advice
RHS Help & Advice
Plum leaf-curling aphid (Brachycaudus helichrysi)
Plants
affected
Plums, damson, gages and wild plums.
Symptoms
Plum leaves become crinkled and curled during the spring. By early summer the infestation has died out so leaves produced after the end of May develop normally, but the earlier damaged foliage remains distorted throughout the summer.
Biology
This aphid overwinters as eggs, which are laid near the buds or in crevices in the bark of wild and cultivated plums. The eggs hatch in late winter as the buds begin to break. Pale green or brownish wingless aphids suck sap from the foliage until late May, when winged forms develop and fly off to colonise various herbaceous plants for the rest of the summer. The aphids return to the trees in the autumn to mate and lay eggs but no feeding damage occurs at that time.
Control
If the trees are small enough to be sprayed adequately, use
a winter wash
(Growing Success Winter Tree Wash)
during December, when the tree is fully dormant.
This will control some of the overwintering eggs.
Information
on winter washes
None of the organic insecticides currently approved for use on plums by home gardeners is likely to give effective control of this aphid once it is protected by the curled leaves. Fortunately, although the damage looks serious, it is something that established trees can tolerate and they will still produce a worthwhile crop. Heavy attacks on a young tree can be more serious as the tree’s growth can be reduced. Small trees can be sprayed when the new foliage is emerging, but not during the open blossom period, with the systemic insecticide thiacloprid (Provado Ultimate Bug Killer Ready To Use). This is absorbed into the foliage and controls the aphids as they feed.