Brief Summary of Minutes of Annual Meeting

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Title: Detection of Xylella fastidiosa and phytoplasmas in processing potatoes affected by a new disorder. Issue: A new disorder of processing potatoes grown in the south-central United States, California, and Mexico has been identified. This disorder as been termed zebra chip because of the dark stripes and streaks produced in potato chips prepared from affected crops. To date, 50,000 acres or more have been affected and losses to one grower in Texas alone are estimated at $2 million. Total losses of $20 million in six states have been estimated. What has been done: Discussions among federal and state scientists have led to research efforts to identify the cause of the zebra chip disorder. WERA-089 researchers have associated the bacterium Xylella fastidiosa with many of the affected plants. Another pathogen, a phytoplasma related to the stolbur organism, has been found in some of the affected crops as well. Research efforts to identify the insect or insects responsible for transmission and confirmatory pathogenicity tests of these pathogens are underway. Impact: This is the first time X. fastidiosa has been associated with a disease of potatoes. The stolbur-like phytoplasma also has not previously been associated with potatoes. The discovery of X. fastidiosa, in particular, is of major concern because strains of this pathogen cause serious diseases of many crops including Pierces disease of grapes and variegated chlorosis of citrus. Some strains of X. fastidiosa are considered select agents by USDA-APHIS. Therefore, this pest is of trade and quarantine significance and could potentially cause significant economic losses in many crop plants. The complete understanding of the etiology of zebra chip will allow development of management strategies that currently do not exist. Primary impacted areas: Research and Extension Funding sources: University support through Hatch Act and State funds, USDA-ARS research funds, National Potato Council, Frito-Lay Corporation, numerous growers, and state potato commissions. Contact information: Greg Bohach, Idaho Agricultural Experiment Station, University of Idaho, Moscow, ID 83844. Phone: 208-885-7173. Email: agres@uidaho.edu. Title: Potato virus Y (PVY) diversity and the effects of PVY on crop production and trade. Issue: PVY includes numerous virus strains which reduce yield and crop quality to different degrees. Recently, PVY strains have appeared in the US that cause internal symptoms in potato tubers. These new strains confound accurate detection, identification, and control methods. They therefore have adversely affected seed potato production, eliminating some growers because certification standards could not be met. Understanding the differential impact of these diverse virus strains on different potato cultivars and accessing their potential impact on trade and quarantine issues is critical. What has been done: In 2004, WERA-089 members were instrumental in developing a management plan for PVY that standardized testing methods among various agencies in the US and Canada. More recently, the management plan has served as a basis for further refining of the testing and identification system to include Mexico (NAFTA) and trading partners in the Far East. Additionally, scientists belonging to WERA-089 have developed improved molecular methods for the rapid detection and identification of these diverse virus strains. Impact: Trade barriers between the US and Canada, and more recently Mexico, have been reduced. Efforts to further open markets in the Far East are continuing. Improved methods of detection and identification of PVY strains have been developed. Primary impacted areas: Research and Extension. Funding sources: University support through Hatch Act and State funds, USDA-ARS, USDA-APHIS, National Potato Council, certified seed growers, state potato commissions. Contact information: Greg Bohach, Idaho Agricultural Experiment Station, Iniversity of Idaho, Moscow, ID 83844. Phone: 208-885-7173. Email: agres@uidaho.edu.

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