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Pierce's Disease
Research Updates

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What is Pierce's Disease?

Pierce's Disease is a bacterial infection, which is spread by bugs that feed on grapevines, particularly the "glassy winged sharpshooter." Grapevines that become infected with PD can quickly become sick and die.

glassy-winged sharpshooter

LABORATORY AND FIELD EVALUATIONS OF IMIDACLOPRID AND THIAMETHOXAM AGAINST GWSS ON CITRUS AND GRAPES

  • Author(s): Castle, Steven; Toscano, Nick; Byrne, Jian; Learned, Mac;
  • Abstract: Much evidence has accumulated over the past few years pointing to the significant role played by imidacloprid (Admire) in reducing GWSS populations. In regions of California where imidacloprid has been used in area-wide control programs, populations of GWSS have declined substantially relative to their pre-action levels. For example, remnant GWSS infestations in Temecula appear to be associated primarily with untreated tracts of vegetation such as organic citrus, while their densities in conventional orchards and vineyards are extremely low. Similarly, GWSS population densities have been substantially reduced in southern Kern County as an outcome of the General Beale Road project. In contrast, other areas with high populations of GWSS such as Ventura/Fillmore and Riverside/Redlands that have not yet participated in area-wide control programs still retain high GWSS populations. The significant reduction of GWSS densities in only those regions where concerted action has been mounted is persuasive, even if it is only indirect evidence of the role that imidacloprid treatments have played in curtailing GWSS populations. By measuring temporal and spatial dynamics of imidacloprid uptake and distribution in mature citrus trees and grapevines, then relating these data to GWSS densities on treated trees and grapevines relative to untreated ones, we have demonstrated the capacity of a single imidacloprid treatment per season to reduce GWSS populations. Questions that initially arose following the first large-scale applications in Temecula in Spring, 2000 concerning the quantity, distribution, and persistence of imidacloprid in citrus trees have now been addressed with the results from our studies. Information that will derive from this project should help optimize future GWSS control efforts.
  • Publication Date: Dec 2002
  • Journal: 2002 Pierce's Disease Research Symposium

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