alternative hosts to develop epidemiologically significant populations of Xf. Thus, the committee provides the following recommendations:

Research should advance the use of vegetation management to reduce populations of GWSS and Xf. This Category 2 research would involve determining the potential of ground cover crops to develop epidemiologically significant populations of Xf; determining leafhopper performance on (survivorship, fecundity, development time) and preference for a broad range of potential ground cover crops; and investigating the use of carefully selected cover crops in vineyards to reduce insect colonization of grape plants.

Currently funded research encompasses a range of approaches for PD–GWSS management, some of which will require years of study and field verification before commercial acceptance is possible. Until then, growers face an expanding infestation that promises serious economic consequences. Research on the use of chemicals or biocides offers the most cost-effective near-term solution to managing GWSS in California vineyards.

Many pesticides can be effective against GWSS eggs, nymphs, and adults. The insects predominate on different plants at different stages, so several types of pesticides with different application techniques or schedules are needed to effectively disrupt the their development. The best studied pesticides for control of GWSS include the systemic formulations, which move through the vascular system of the plant; the nonsystemics, which act after application to the surface of the plant; and inert compounds, which coat the plant surface to repel insects.

Although insecticides offer reasonably good short term management for such control to remain economically feasible and environmentally acceptable, the committee urges research on improved application mechanisms that will reduce drift and thus exposure of nontarget organisms. The committee also recommends the pursuit of additional narrow-spectrum chemical controls. The determination of the social and environmental effects of any recommended compound and the rigorous economic assessments of insecticide effectiveness within an EBPM scheme are also recommended. In general, research should identify management strategies or approaches that minimize the use of insecticides or that promote the use of narrow-spectrum, sustainable pesticides. Research on chemicals should focus on the following areas:

• Identify and develop more efficient means of delivery of the chemical to the target.

• Identify novel pathogen targets for which highly specific chemicals can be identified or developed.

• Determine the social and environmental consequences of using these compounds.

Front Matter (R1-R16)

Executive Summary (1-20)

1 Pierce's Disease and the Glassy-winged Sharpshooter: Their Biology and the Challenges of Their Management (21-44)

2 Developing Priorities for Research (45-54)

3 Host-Vector Interaction (55-87)

4 Plant-Pathogen Interaction (88-104)

5 Vector-Pathogen Interaction (105-113)

6 References (114-152)

Appendix A: Committee Biographies (153-157)

BANR Publications (158-161)