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United States Department of Agriculture

Agricultural Research Service

Research Project: Epidemiology and Management of Pierce's Disease and Other Maladies of Grape

Location: Crop Diseases, Pests and Genetics

Title: Optimizing EPG settings to record blue-green sharpshooter X waves for future studies of grape host plant resistance to Xf inoculation

item Backus, Elaine

Submitted to: CDFA Pierce's Disease Control Program Research Symposium
Publication Type: Proceedings
Publication Acceptance Date: November 20, 2013
Publication Date: December 6, 2013
Citation: Backus, E.A. 2013. Optimizing EPG settings to record blue-green sharpshooter X waves for future studies of grape host plant resistance to Xf inoculation. Proceedings of the CDFA Pierce's Disease Control Program Research Symposium. p. 3-10.

Interpretive Summary: Pierce’s Disease (PD) of grape, a lethal plant disease caused by the bacterium Xylella fastidiosa (Xf), has potential to devastate grape production in California, worth $4.1 billion/year. Due to expense, environmental damage, and potential impact on honey bees caused by insecticides used to control sharpshooter leafhoppers (vectors of Xf), there is a pressing need to develop grape varieties resistant to the bacterium and/or sharpshooters. The long-term goal of the research program is to work with grape breeders to aid development of a grape rootstock variety that is resistant to sharpshooter inoculation of Xf bacteria, thereby preventing Xf infection. The present research provides the first step in achieving this goal, use of electrical penetration graph (EPG) monitoring as a means of testing grape varieties for resistance to sharpshooter inoculation of Xf. The deliverable for grape growers from this research would be a rootstock variety bearing multiple forms of resistance to Xf and sharpshooters.

Technical Abstract: The long-term goal of the research reported in this review is to develop methodology for assessment of grapevine resistant to sharpshooter inoculation of Xylella fastidiosa(Xf)into healthy grapevines, thereby preventing Xf infection. Such a trait would be quite different from the more common mechanism of resistance to Xf, i.e., resistance to systemic bacterial spread and multiplication, after vector inoculation has already occurred. Identification and selection of an anti-inoculation trait depends upon two research objectives: 1) understanding behavioral mechanisms of Xf inoculation by sharpshooters, and 2) devising a rapid method for identifying grapevines that deter inoculation behaviors. Electrical penetration graph (EPG) monitoring of insect feeding research has revealed the behavioral mechanism of Xf inoculation. The inoculation behavior is represented by the sharpshooter EPG X wave. The present research showed that the same X wave components are visible for the blue-green sharpshooter as for the glassy-winged sharpshooter. Thus, the present work supports that: 1) EPG will be a useful technology for detection of Xf inoculation behaviors, 2) EPG monitor settings can be optimized for recordings of the blue-green sharpshooter X wave, and 3)those settings may be different from the best settings for glassy-winged sharpshooter recordings.

Last Modified: 9/22/2014
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