When the cold wet weather of May gave way to a warm evening early in June I went to spray the fruit trees with a foliar feed. Walking through the apples I was struck by the contrast between a few trees with every leaf crimped and the trees whose leaves were in full vigour. The culprit was black aphid. I made a note of the varieties so affected and went back next morning with a hand lens to examine the trees.
On closer inspection I observed that the trees could be assigned to one of three categories: those whose every leaf was affected, those only partially affected and those - the majority - completely free of any aphids.
All the trees were on M9 and planted between 2004 - 6. They are trained as oblique cordon, espalier and dwarf pyramid.
The varieties totally affected were Fearn’s Pippin, Golden Pippin and Court Pendu Plat. Varieties only partially affected were Pitmaston Pineapple, James Grieve, Alfriston and Sturmer Pippin. Varieties completely free of aphid were Ashmead’s Kernel, Adams’s Pearmain, Forge, Pixie, Cornish Aromatic, Swaar, Pitmaston Russet Nonpareil. The aphids affected trees irrespective of the method of training.
These trees all grow on one allotment. Trees growing on other allotments were completely free of any form of aphids.
Back home with my notes I started to go through the literature beginning with the classic of its time Handbook of Insects injurious to Orchard and Bush Fruits by Eleanor A. Ormerod, 1898. There is no reference here to black aphids affecting apples; the green and rosy apple aphid are cited. This seems to set the standard of reference down to our times. The black aphid where it is mentioned is referred to as the ‘cherry aphid’.
How can this be? Why is the black aphid not cited as a problem pest in relation to apples? And why was it present in such numbers on a few varieties while those next to it and in neighbouring rows were completely free of it?
It was not until June 26th, over three weeks later, before I saw the first evidence of a green aphid - being farmed out by ants - on an Allen’s Everlasting, planted within the last year.
One intriguing note in Bonham Bazely’s Growing Tree Fruits caught my attention - ‘Aphids are sap-suckers but they prefer their diet to be slow-moving, so they often land on trees that are not thriving too well, disregarding the more vigorous trees with strong growth.’ (page 51)
Did those cold wet winds which blew from France across the Channel in May bring the black aphids with them?
Ian Harrison
Rosy apple aphids may be the culprits - see comment below by Derek Rye

