None of the insecticides approved for use on apple in the UK are recommended by the manufacturer for control of apple leaf midge.
- The full approval for spirotetramat (Batavia) on apples for the control of sucking insect pests offers some control of apple leaf midge, although growers may prefer to reserve its use for more difficult to control pests such as woolly aphid and rosy apple aphid. 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’.
- The bioinsecticide fatty acids (Flipper) has an EAMU approval for use on apples (3419/19). It is effective at controlling sucking insect pests such as aphids, whitefly and mites, so is likely to offer incidental control of leaf midge when applied for other pests. It is known to complement the use of Batavia as it provides quick ‘knockdown’. Its safety to beneficial insects such as Typhlodromus pyri and the parasitic wasp Platygaster demades (see below) is unknown, but it is generally safe to many other predators and parasitoids, so is considered to be more suitable to IPDM programmes than the synthetic pyrethroids.
- Research in AHDB Horticulture Project TF 129 demonstrated that methoxyfenozide (Runner), spinosad (Tracer) and thiacloprid (Calypso) were ineffective at controlling apple leaf midge.
- The synthetic pyrethroid products showed partial control in TF 129.
- Deltamethrin (Decis Forte) and lambda-cyhalothrin (Hallmark, Major) are approved on apples, but in the case of lambda-cyhalothrin, there is a 365 day harvest interval, so it can only be used in nursery crops.
- These synthetic pyrethroid products don’t list apple leaf midge on their product recommendations, but offer incidental control when applied to control other pests.
Application should be timed to coincide with the egg-laying period because they are likely only to be effective against adults and young larvae as they hatch from eggs. Once the larvae are enclosed in the leaf rolls, they are very difficult to control with insecticides.
- Pyrethroid insecticides are contact acting only.
- They are harmful to the orchard predatory mite Typhlodromus pyri and many other beneficial insects including the parasite Platygaster demades which is an important natural enemy of apple leaf midge.
- For these reasons, they should only be used as a last resort and outbreaks of apple leaf midge should be tolerated.