Leafhoppers Transmit Deadly Grapevine Disease in Italy

The grapevine disease Flavescence dorée has been called “catastrophic.” Impacts include yield reductions, and reduced wine quality. The disease spreads rapidly and can affect 80-100% of the vines in a few years. The disease is spread by leafhoppers who acquire the organism while feeding on infected plants and then spread the disease when they feed on healthy plants. Spraying to control the leafhopper is mandatory in regions where the disease is known to exist.

“The leafhopper Scaphoideus titanus Ball (Hemiptera: Cicadellidae) is a serious pest of grapevines in Europe as it transmits the phytoplasmas of Flavenscence dorée (FD). … the eggs start to hatch in the middle of May, and nymphs can be found until the middle of July… The adults are present from the end of June until the middle of October.”

“Nymphs from the third instar onward acquire phytoplasmas by piercing the leaves and stems of infected grapevines. After a latency period of 4-5 weeks, during which time they become adults, they can transmit FD phytoplasmas to healthy grapevines. In Italy, insecticide treatment against S. titanus are mandatory in the districts where FD is present. The active ingredients include neonicotinoids and organophosphates; in vineyards subject to organic farming S. titanus is controlled with pyrethrum.”

Authors: F. Lessio, E.B. Mondino and A. Alma
Affiliations: University of Turin, Grugliasco, Italy
Title: Spatial patters of Scaphoideus titanus (Hemiptera: Cicadellidae): a geospatial and neural network approach.
Publication: International Journal of Pest Management. 2011. 57(3):205-216.

Grape Mealybug Control in California Depends on Insecticides

Four species of mealybug feed on grapes in California. They suck out plant content and excrete unused plant material. The result is a layer of sticky, wet honeydew on which thick, black, sooty mold grows. The strict quality standards set by the grape industry and demanded by consumers have led to a dependence on insecticides for controlling mealybug populations.

“Although more vineyards are becoming infested, populations within infested areas are declining because the judicious use of insecticides has successfully lowered mealybug populations in areas that are infested.”

“Season-long control programs for vine mealybug are typically comprised of a combination of insecticide treatments assisted by biological control. … Promoting parasites is very important because they are active late in the growing season and can reduce vine mealybug populations before the pest begins to move to the lower part of the trunk after harvest [where they are protected from insecticides].”

Authors: Chuck Ingels, David Haviland and Steve Quashnick*
Affiliation: UC Cooperative Extension and *Wilbur Ellis
Title: Vine mealybug management in wine grapes in the northern San Joaquin Valley.
Publication: CAPCA Adviser (2012) April:34-37.