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PIERCE’S DISEASE OF GRAPEVINES

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Muhammad Kamran M.Sc(Hons) Agri.EntomologyUniversity College of Agriculture,

University of SargodhaPakistan

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Pierce’s disease of grapevinesoFirst described in California in 1892.oPierce’s disease (PD) of grapevines is a lethal disease.

severely limits areas where grapevines can be grown.oCausal organism is Xylella fastidiosa (Xf). oXf is a gram-negative bacterium, specific strains are capable

of infecting grapevines.oThe Xf bacterium resides in the xylem of the grapevine. oPD is transmitted to the grapevine by:

• Sharpshooter: (BGSS) Graphocephala atropunctata (GWSS) Homalodisca vitripennis  (Cicadellidae: Homoptera)

• Spittlebugs 2

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(courtesy A.C. Goheen; reproduced from Compendium of Grape Diseases, 1988, American Phytopathological Society, St. Paul, MN).

The glassy-winged sharpshooter leafhopper

o Typical PD symptoms begin to appear in hot and dry weather.o Reliable diagnosis is dependent upon• Bacterial culturing• Enzyme-linked immunosorbent assay (ELISA)• Polymerase chain reaction (PCR).

Photos by Damon Smith, Oklahoma State University

Symptoms consisting of marginal leaf necrosis, leaf blade drop, leaf scorch, shriveled berries, dieback, and death

(courtesy B. Bextine, Fletcher and Wayadande, 2002, The Plant Health Instructor).

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Disease cycle/Mode of transmission• Acquisition efficiency is directly proportional to the

population of the bacteria from the infected hosts and the sharpshooter feeding site.• Attachment or retention of the acquired bacteria into the

vector foregut forming a biofilm.• Pathogen must be detached and introduced into a new

host during vector feeding. • Bacterial cells attach to the xylem vessel and multiply

forming biofilm-like colonies that occlude the xylem.• Disrupts water transport throughout different parts of the

plant exacerbated by gum deposits, tyloses or deposition of other bacterial- or plant-derived compounds. 4

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Management

• Winter temperatures at or below 10ºF for two to three days is required for a vineyard to be considered at low-risk for Pierce’s disease. Otherwise, vineyards are considered at medium- to high-risk (Anas et al., 2008).• Purchasing clean stock from a reliable source.• Use systemic insecticides to control insect pests in

vineyards.• No chemical management options currently exist for

Pierce’s disease.

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