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Vineyard weeds found to host Pierce's disease of grapes
September 22, 2005New research just released in the September issue of Plant Disease suggests that weeds commonly found in California's wine country may enable the spread of Pierce's disease of grapes, one of the most destructive plant diseases affecting grapes.
Pierce's disease is caused by Xylella fastidiosa, a bacterium transmitted by sharpshooters and spittlebugs. In response to outbreaks of Pierce's disease in central California, plant pathologists studied 29 weed species commonly found in California's San Joaquin Valley to see if the bacterium could survive on the weeds. Perennials and known feeding and breeding hosts of the glassy-winged sharpshooter were tested first, then plants particularly abundant in or near vineyards.
"Our objectives were to determine the fate of Pierce's disease infections in previously untested plant species associated with southern San Joaquin Valley vineyards, and compare survival of the infections in selected field and greenhouse-grown plants," said Christina Wistrom, staff research associate in the Department of Environmental Science, Policy and Management, University of California, Berkeley, CA.
The study revealed that environmental conditions have a major impact on bacterial growth in host plants. "Multiplication and systemic movement of X. fastidiosa varied among different plant species and environmental conditions, so weed species in vineyards must be evaluated on an individual basis to determine their potential contribution to Pierce's disease," Wistrom said. "Currently, Pierce's disease is controlled by reducing populations of the insect vector, either through insecticide sprays or habitat modification to remove insect breeding host plants. Our study reinforces the need for weed control in irrigation ditches and roadsides adjacent to vineyards, in regions with chronic Pierce's disease and established populations of sharpshooters, especially in warm weather," she said.
The researchers recovered X. fastidiosa from 27 of 29 species in greenhouse tests. Sunflower, cocklebur, annual bur-sage, morning glory, horseweed, sacred datura, poison hemlock, and fava bean were most frequently infected. "Our study confirmed that plant species cannot be simply classified as either 'hosts' or 'nonhosts' of X. fastidiosa, but vary considerably among plant species in supporting growth and movement of the bacterium," Wistrom said. In addition, she noted that the joint lab and field experiments showed that environmental conditions strongly influenced how rapidly the bacteria multiplied within the plants.
American Phytopathological Society
The study revealed that environmental conditions have a major impact on bacterial growth in host plants. "Multiplication and systemic movement of X. fastidiosa varied among different plant species and environmental conditions, so weed species in vineyards must be evaluated on an individual basis to determine their potential contribution to Pierce's disease," Wistrom said. "Currently, Pierce's disease is controlled by reducing populations of the insect vector, either through insecticide sprays or habitat modification to remove insect breeding host plants. Our study reinforces the need for weed control in irrigation ditches and roadsides adjacent to vineyards, in regions with chronic Pierce's disease and established populations of sharpshooters, especially in warm weather," she said.
The researchers recovered X. fastidiosa from 27 of 29 species in greenhouse tests. Sunflower, cocklebur, annual bur-sage, morning glory, horseweed, sacred datura, poison hemlock, and fava bean were most frequently infected. "Our study confirmed that plant species cannot be simply classified as either 'hosts' or 'nonhosts' of X. fastidiosa, but vary considerably among plant species in supporting growth and movement of the bacterium," Wistrom said. In addition, she noted that the joint lab and field experiments showed that environmental conditions strongly influenced how rapidly the bacteria multiplied within the plants.
American Phytopathological Society
Grapes Current Events and Grapes News RSSIce cream researchers making sweet strides with 'functional foods'
A comfort food, a tasty treat, an indulgence - ice cream conjures feelings of happiness and satisfaction for millions. Ice cream researchers at the University of Missouri have discovered ways to make ice cream tastier and healthier and have contributed to ice cream development and manufacturing for more than a century.
Researchers explore new ways to prevent spinal cord damage using a vitamin B3 precursor
Substances naturally produced by the human body may one day help prevent paralysis following a spinal cord injury, according to researchers at Weill Cornell Medical College. A recent $2.5 million grant from the New York State Spinal Cord Injury Research Board will fund their research investigating this possibility.
Tension on the grapevine
Predictions of grape yields are extremely important to juice processors and wineries; timely and precise yield forecasts allow producers to plan for harvest and move the highly perishable grape crop from vine to processing efficiently.
Great wines come from great soils
The world's greatest wines are the result of a threefold synergy among grape variety, human input, and something called the "terroir" -- a term often defined as the vineyard site, soil, and climate.
Fruit fly pest identified in wine grapes
A newly recognized pest in Oregon continues to concern fruit growers and researchers with the recent discovery of a Spotted Wing Drosophila fly in a sample of Willamette Valley wine grapes.
UT Southwestern study shows how substance in grapes may squeeze out diabetes
A naturally produced molecule called resveratrol, found in the skin of red grapes, has been shown to lower insulin levels in mice when injected directly into the brain, even when the animals ate a high-fat diet.
Future diabetes treatment may use resveratrol to target the brain
Resveratrol, a molecule found in red grapes, has been shown to improve diabetes when delivered orally to rodents. Until now, however, little has been known about how these beneficial changes are mediated in the body.
Genetic discovery could break wine industry bottleneck, accelerate grapevine breeding
One of the best known episodes in the 8000-year history of grapevine cultivation led to biological changes that have not been well understood - until now.
Zoo volunteers help explain mysteries of the genome
As the University of Leicester approaches the 25th anniversary of the discovery of DNA fingerprinting (September 10), Leicester geneticists interested in a particular type of DNA are receiving some help from an unusual band of assistants.
Study shows how to boost value of Alzheimer's-fighting compounds
The polyphenols found in red wine are thought to help prevent Alzheimer's disease, and new research from Purdue University and Mount Sinai School of Medicine has shown that some of those compounds in fact reach the brain.
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