Source: Whitney Cranshaw, Colorado State University, Bugwood.org
Description and life cycle
Rose leafhopper resembles the white apple leafhopper in appearance, habits, and tree injury. However, this species is distinguished as a nymph by the presence of small black spots on the thorax and wing pads. Adults are indistinguishable unless dissected. Rose leafhopper overwinters on multiflora rose and brambles.
The first of the three generations per year stays on the overwintering host, with the adults dispersing to apple trees in early June. Nymphs appear on apple trees in early July and adults again in early August, preceding the appearance of white apple leafhopper adults. Watersprouts often have heavier populations of second-brood leafhoppers than other areas of the tree. Moderate drought conditions favor outbreaks.
Besides injuring leaves, leafhoppers deposit numerous small spots of excrement on fruit, potentially reducing its quality. Honeydew secreted by leafhoppers may cause black specks on fruit and foliage.
Monitoring and management
Examine five trees per block, 20 leaves per tree, and check the undersides of leaves for nymphs. One leafhopper per leaf during second-generation activity (third cover) is justification for applying an insecticide. Populations of two or more leafhoppers per leaf during third-brood activity in August and September should be treated. Sprays should be timed for young nymphs. Insecticides recommended for aphid control should adequately control leafhoppers also. Specific chemical recommendations for home gardeners are in Fruit Production for the Home Gardener, and recommendations for commercial growers are in the Penn State Tree Fruit Production Guide.