Leafhoppers are minor pests of apple with a life cycle that involves overwintering as eggs and hatch in the spring to feed on the undersides of leaves causing speckling damage.
Very large populations of adults and nymphs can build up in apple orchards over a number of seasons if effective insecticidal control measures are not applied occasionally. Leaf speckling damage increases as the season progresses and can give the tree a bleached appearance by the end of the season. Intensive damage reduces vigour and fruit size and adversely affects fruit bud formation.
Fruit surfaces become contaminated by numerous small brown spots of excrement. This contamination is easily washed away by water, including by rain, during post-harvest drenching or grading.
Leafhoppers are small and usually green or yellow in colour and are easily distinguished from aphids as they readily jump and fly.
Leafhopper populations are best monitored by visual inspection for the characteristic speckling damage and for the leafhoppers themselves which are often present on the undersides of damaged leaves.
A spray of an approved insecticide should be applied in summer against adults and nymphs if leaf damage starts to become unsightly and is increasing.
Control
Control in organic orchards
Choices of insecticides - efficacy factors and safety factors
Further reading
Leafhopper - additional information