Attacks of woolly aphid tend to be sporadic and it is important to watch for sign of infestation moving onto young shoots in June (see ‘Monitoring’) and treat only when necessary.
- A high volume spray of an approved insecticide should be applied in spring or early summer as soon as potentially damaging infestations are detected.
- Successful control depends on efficient wetting and good distribution of spray.
- High volume spraying is likely to be more effective as the spray has to penetrate the protective woolly covering of the aphid and reach colonies living in cracks and on the undersides of branches.
- Flonicamid (Mainman) is specifically recommended for control of woolly aphid on apple.
- Flonicamid (Mainman) is a good choice because it is selective, has low toxicity to natural enemies and is partially systemic.
- However, in recent years, growers have found flonicamid and all other products to be less effective against woolly aphid. Spirotetramat (Batavia) now offers best control. It must be applied after flowering and works best when pests are moving from brown wood to green tissue. It will prevent population build-up but does not offer pest ‘knockdown’.
- Fatty acids (Flipper) has an EAMU approval on apples for controlling aphids and has increased the control options available should growers prefer to reserve other insecticides for control of pests later in the season. It is known to complement the use of Batavia as it provides quick ‘knockdown’.
- Use of synthetic pyrethroids, which are harmful to natural enemies, should be avoided.