Apple Blossom Weevil

Key Points

  • Apple Blossom weevil infestations can cause significant crop losses
  • The presence of capped blossoms is a characteristic symptom of attack
  • Lorsban WG should be applied at bud burst timing
  • Applications of Lorsban WG can control Apple Blossom weevil and many other fruit pests

Introduction

Apple trees, and sometimes pear, near other woodland are most likely to be attacked by Apple Blossom weevil (Anthonomus pomorum). Characteristic symptoms of attack are the presence of capped blossoms. These remain on the tree at petal fall, having failed to open during flowering. In severe attacks a large proportion of the blossom is damaged, leading to significant crop loss.

Biology

Adult weevils are black or dark brown in colour with fine hairs and a light coloured V marking on the back. They can grow to about 5mm in length and have a long snout. Feeding takes place during March and April by boring into blossom buds. Eggs are normally laid between bud burst and green cluster growth stages. Each female weevil can lay between 40 and 50 eggs, single eggs being placed in individual blossom buds.

Eggs hatch between green cluster and pink bud stages, normally being complete by late April. Creamy-white larvae with a brown head then feed on stamens until they reach maturity after approximately 3 – 4 weeks. Pupation lasts about two weeks, after which a new adult weevil bores out through the dead petals and proceeds to feed on the underside of leaves. Adult activity declines from June onwards as weevils rest under loose bark or in nearby woodland until the next spring.

Product Choice

Applications of Lorsban* WG (active ingredient chlorpyrifos) at bud burst timing will control infestations of Apple Blossom weevil. Do not apply to crops in flower or to those in which bees are actively foraging. Do not make applications when flowering weeds are present.