Expert Report

Each report is produced by a committee of experts selected by the Academy to address a particular statement of task and is subject to a rigorous, independent peer review; while the reports represent views of the committee, they also are endorsed by the Academy. Learn more on our expert consensus reports.

The glassy-winged sharpshooter is one of the more recent invasive pests to afflict California agriculture. The insect transmits a bacterial pathogen that causes Pierce's disease, which has impaired production of wine, table, and raisin grapes in California. The report recommends strengthening the process and the priorities for research funded by state agencies and wine industry groups to address Pierce's disease and its vector. Research should be focused on identifying feasible options for controlling the spread of the disease and providing sustainable approaches that are adaptable and affordable over the long term. Several avenues of research be pursued more intensely including the genetic makeup of the pathogen that triggers Pierce's disease, understanding the mechanisms that make grapes resistant to the disease, the possibilities of introducing predator enemies to the sharpshooter, and new ways to manage the planting of crops to help avoid spread of the disease.

Key Messages

  • Research is needed to advance the use of classical biological control (predators and parasitoids) of the insect.
  • Research should identify management strategies or approaches that minimize the use of insecticides or that promote the use of narrow-spectrum, sustainable pesticides.
  • Significant progress already has been made in elucidating the biology of the PD-GWSS problem. Plausible management strategies have been tested and either advanced to future studies or eliminated.
  • The greatest concern is that the scientific merit of the proposals is not receiving consistent scrutiny and attention. That could hinder the program's ability to move forward, because decisions about priorities and direction need to be made using solid, reproducible results.
  • There still are significant knowledge gaps in critical areas. The committee noted an absence of uniformity and communication in the process through which PD-GWSS research projects are selected, accepted, and funded.
  • When this study began, the committee noted significant gaps in knowledge about the characteristics and biology of pathogen and insect and how they interact with each other and the host plant. Through the funding program coordinated by CDFA as well as other national and international institutions, significant, albeit in insufficient, strides are being made to remedy that lack of information.