[Grubbypaws]

I have a wonderful apple espalier which I have trained against a sunny wall but no one told me about the ants! The minute a leaf touches the wall they have a bridge to invade and start 'farming' aphids. All trunks stakes and support wires are covered in fruit tree grease so they are unable to access the espalier by those routes but it is trained against a sunny wall as it is meant to be and leaves are going to touch!

Apart from daily vigilance has any one got a solution to this?