One-off (organic?) aphids control
We need to ask a gardener to apply an insecticide to a cherry tree. Neighbours have complained about the tree being infested by insects.
For reasons I cannot go into, there is no regular access to the tree. So we want to ask someone to come once and apply some kind of insecticide.
We want it to be organic – so no adverse effects on other wildlife and humans. What would be a sensible option in this scenario, i.e. what should we ask the gardener to do/apply?