Chemical control
The usual method of control of apple blossom weevil is to apply a spray of a broad-spectrum insecticide against adults at bud burst when most adults have migrated into the apple crop but before significant egg-lying has occurred.
- The organochlorine insecticides DDT and HCH were traditionally used for this purpose and were highly effective but were withdrawn from use many years ago.
- Fatty acids (Flipper) is specifically recommended for control of apple blossom weevil on apple.
- It is likely that indoxacarb (Steward or Explicit), when used to control tortrix, codling or winter moth caterpillars, will provide incidental control of apple blossom weevil, although their efficacy has not yet been explored.
- Synthetic pyrethroids such as deltamethrin (Decis Forte) are also highly effective when used against other pests, but their use should be avoided as they are harmful to the orchard predatory mite Typhlodromus pyri and a wide range of other natural enemies.
Insecticide resistance
Resistance of apple blossom weevil to insecticides is not known and is unlikely to occur.
Cultural control
Young, dwarf apple trees have smooth bark, which provides few overwintering sites for the weevil in the orchard. Moreover, well-managed orchards have little leaf litter in which the weevils can overwinter, so most weevils overwinter outside the orchard in nearby woodland and hedgerows. The weevil is less of a problem in orchards that are not adjacent to woodland or hedgerows.
- Loss of even quite a high proportion of buds may be of limited importance on apple trees that have high numbers of apple buds and on varieties where damaged flowers do not continue to develop into mature fruits.
- Good tree management and nutrition will greatly reduce the impact of this pest.
- In organic orchards where the pest is especially troublesome, providing adequate nitrogen to the trees is important to maintain fruit bud numbers and quality.
- On a limited scale, it might be feasible to remove and destroy capped blossoms before the weevil completes its development and emerges. This could be done when hand thinning of fruitlets is done. This should reduce the risk of allowing damaged fruits to mature.
- On a limited scale, it might be possible to provide artificial hibernation sites for adults (e.g. trunk bands) in June before the weevil moves to its hibernation quarters. The artificial hibernation sites could then be removed and the weevils destroyed. This approach probably hasn’t been tried and may not be very effective.