Supervised control of apple pests in southern England

Abstract

Supervised control involving use of insecticides and acaricides only when assessments showed that these were necessary, was compared with normal spray programmes applied to apple tree plots of at least 0·4 ha on 23 sites for 1–5 years at each site, giving a total of 57 trials. Pest assessments and spray thresholds were adapted from those in use in the Netherlands in 1974. The growers' usual insecticides and acaricides were used in the supervised programmes when necessary and their normal fungicidal programmes were used. Pests reaching the spray threshold included aphids (rosy apple, apple-grass, green apple, rosy leaf-curling, and woolly), apple sucker, common green capsid, winter moth, apple sawfly, tortricids (fruitlet mining, fruit tree, and summer fruit), codling moth and fruit tree red spider mite. Minor pests included common earwig, apple leaf midge and green and brown leaf weevils. An average of 3·2 insecticides and acaricides was applied per annum to the supervised plots compared with 5·0 in the growers' programmes. The greatest savings were pre-blossom and at petal fall. Little pest damage to foliage was recorded with either programme. Approximately 4·1 % of fruit on the supervised plots showed pest damage (on a severe assessment) compared with 2·9% with the growers' programmes. Supervised control saved 10·78% of growers' normal pesticide costs; it can prevent serious pest damage while utilizing smaller amounts of insecticides and acaricides.