There is concern among New Jersey cranberry growers of a potential increase in blunt-nosed leafhopper populations because of recent changes in pest management strategies (e.g., adoption of new reduced-risk products and decreased applications of broad-spectrum insecticides). Bluntnosed leafhopper is of particular concern because they can transmit cranberry false blossom disease.
This leafhopper has one generation a year. Blunt-nosed leafhopper eggs overwinter and begin to hatch in early May. The nymphs (Picture 1) will go through five instars in about a month. The adults begin to appear early in July and are most abundant in late July. Numbers of this species start to diminish by the first week in August. The adults have a characteristic blunt head and vary from light yellowish-gray to dark brown (Picture 2). Eggs are laid in August-September.
Nymphs and adults get their food by sucking the plant juices of the cranberry with their piercing-sucking mouthparts. This direct injury is, however, not noticeable. They are most important as vectors of false blossom disease.
Scouting and Control
The most important point in leafhopper control is locating the infestation. Monitoring for this insect is accomplished best with an insect sweep net. Nymphs can be monitored before bloom using sweep nets. Nymphs before bloom are small; thus, you may need to freeze the samples (to kill them), and then count the number of nymphs under a microscope or using a magnifying lens. Perform sweep sets of 25 sweeps each. The recommended number of sweep sets is: 1 per 1–10 acres, at least 10 sweep sets per 10–20 acres, and 1 sweep set per 2 acres for more than 20 acres. In cases of high blunt-nosed leafhopper numbers, we recommend application of a broad-spectrum insecticide, such as Lorsban. The neonicotinoids Actara and Assail are very effective against blunt-nosed leafhoppers and can be used to target the adults after bloom. There is no threshold so decisions should be made based on current numbers and prior infestation history. Broad-spectrum insecticides will disrupt biological control particularly the natural enemies (predators and parasitoids) of Sparganothis fruitworm, so their use should be minimized to areas of high blunt-nosed leafhopper populations.