Visual inspection
- Orchards should be inspected regularly, preferably fortnightly, from the green cluster growth stage (April) through to mid-summer (end of June) for signs of infestation and or damage.
- Critical growth stages are late green cluster (so that a pre-blossom aphicide may be applied) and during blossom when populations are often increasing rapidly.
- On Bramley, where flowering is often very protracted when frosts occur, pre-blossom treatment is especially important as it can be several weeks before another opportunity to spray while the crop is not in flower.
- Examine at least 25 trees per orchard for signs of damage.
- The threshold for treatment increases as the season progresses but presence of the aphid at the green cluster stage, even on only one of the 25 trees inspected, is enough to warrant treatment.
- Rosy apple aphid populations are particularly damaging between bloom and early fruitlet development when fruit cell division is occurring.
- Infestations that occur after this time (more than a month after full bloom) are less damaging.