The severity of infestation by green apple aphid should be determined in each orchard when pest assessments are done from late June to the end of August.
- Examine the growing shoots (preferably all, but examining two shoots per tree carefully) in at least 25 trees per orchard.
- Application of an insecticide to control green apple aphid should be considered if more than 30% of shoots are infested with one or more aphids or if 10% of shoots have infestations causing leaf curling.