The severity of infestation by rosy leaf curling aphid should be determined in each orchard when pest assessments are done before blossom at the green cluster to pink bud growth stage.
- Attention should be focussed on highly susceptible varieties (e.g. Golden Delicious) and in places where the pest occurred the previous year.
- Examine the rosette leaves over the whole tree on at least 25 trees per orchard.
- Localised application of an insecticide to control green apple aphid should be considered where infestation is detected.