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Published:  23 July, 2008

Ximed, a pharmaceutical development company, claims to have discovered a natural formulation' that eradicates Pierce's Disease, which has devastated vast areas of vineyard in California. According to the company, terpenes, which are naturally occurring, low-toxicity, botanical substances used by plants in their defence mechanisms, have been adapted to cure the insect-transmitted disease. Ximed says it has conducted nine years of research and trials in South Carolina. When applied early in the growing season, when soil moisture was high, its terpene-based formulation eradicated the disease successfully from more than 80% of vines. Additional trials took place in southern California, in the driest period after harvest, when soil and climatic conditions hindered the formula's uptake. The formula successfully revived 36% of heavily infested vines. Pierce's Disease, named after the US scientist who investigated it, is caused by the bacterium Xylella fastidiosa, which affects peach and almond trees as well as vines. It is transmitted by several species of leafhopper insects, most notably the glassy-winged sharpshooter (GWS). The sharpshooters feed on the sap in the vine's xylem and the contaminated sap results in the plant's water-conducting vessels becoming plugged. This can lead to the vine's death within three years. Young vines are more susceptible and usually die within the first year of infection, while older plants may survive for up to five years, but are slow to resume growth in the spring and new shoots are stunted. It is the increasing encroachment of the GWSs, believed to have emanated from south of the US border, that is worrying vine growers most. GWSs have infested vineyards in southern California and are moving north towards California's major and premium wine-producing regions. John McLaren, director of the Wine Institute of California in London, told Harpers: If this formula is what it purports to be, it could be very exciting news for the Californian wine industry.'