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WERA_OLD020: Virus and virus like diseases of fruit trees, small fruits and grapevines

Duration:

October 01, 2001 to September 30, 2006

Administrative Advisor(s):

Ralph Cavalieri (WN.P) - Research

NIFA Reps:

Kitty Cardwell

Statement of Issue(s) and Justification:

Diseases caused by viruses and virus?like organisms continue to be important to tree fruit and berry industries in the United States and Canada. The impact of these pathogens can be significant and often limit the economic and biological viability of fruit production. WCC-020 facilitates a reduction in the impact of disease on this sector of agriculture by providing a forum for information exchange at annual meetings and by establishing contacts that encourage communication throughout the year. The discovery of Plum pox virus in North America in 1999 had an immediate impact on the tree fruit and nursery industries. Globally, this aphid-transmitted virus is the most economically important virus of stone fruits. The diagnosis of Plum pox virus was hastened because WCC-020 provided a network of researchers and specialists that were able to make the preliminary diagnosis and insure that the necessary testing was conducted to confirm this diagnosis. WCC-020 continues to foster experts that provided leadership and advice in developing testing and management strategies. Pollen-borne ilarviruses and nematode-transmitted nepoviruses cause significant decreases in orchard, raspberry, blueberry and vineyard production throughout the United States. Citrus tristeza virus (CTV) is a major limitation to citrus production worldwide and efforts to control this disease in California and Arizona have been critical to maintaining the viability of this fruit tree industry in the western United States. Grapevine leafroll virus, corky bark, rugose wood, Rupestris stem-pitting associated virus and other graft-transmissible pathogens contribute to the decline of grapevines, decrease vegetative growth and fruit yields. Raspberry bushy dwarf virus causes serious yield and quality losses in Rubus spp. and Blueberry scorch carlavirus is becoming a major disease problem in blueberry in the Pacific Northwest and in the Northeast. WCC-020 also promotes the exchange of information on diseases caused by isolates of the bacteria Xylella on citrus (variegated chlorosis), coffee (leaf scorch), peach (phony), almond (leaf scorch), and grape (Pierce's disease). Phytoplasmas that cause diseases such as Western X disease, pear decline, and peach yellow leafroll seriously reduce the production of stone and pome fruits in the western region of the United States. Although bacterial in nature, phytoplasmas and Xylella spp. have many features in common with viruses such as systemic infection, vector transmission, and graft transmission.

(see attachment below for complete issues and justification)

Objectives

1. Promote and improve communication and cooperation among entomologists, plant pathologists, horticulturists, and other professionals concerned about plant health to determine the vectors of virus and virus-like diseases and to investigate the role of vector biology in the epidemiology of diseases.
2. Encourage, facilitate, and speed work on the cause and control of newly detected diseases and disorders by increasing contacts and communication on newly discovered problems likely to be caused by viruses or virus-like agents.
3. Facilitate rapid adoption and proper use of newly developed techniques and information that aid in the characterization and detection of virus and virus-like plant pathogens.
4. Evaluate regional fruit tree inventories of operational clean stock programs with horticulturists to select superior clones for use by industry.
5. Provide a source of research information and service to quarantine and certification agencies, to germplasm repositories, experiment station and government administrative agencies nationwide and the tree fruit, small fruit and grapevine industries.

Procedures and Activities

Expected Outcomes and Impacts:

• Since its inception, WCC-020 has a proven record of collaborative research efforts among its committee members. We anticipate that the generation of new information on the cause and management of fruit tree virus and virus-like diseases will continue to be the primary product resulting from the collaborative interactions of WCC-020 members. More specifically, the outcome of our collaborative investigations will include, but is not limited to, advances in the following areas during the next three years: 1) Identification and characterization of the phytopathogenic viruses, viroids, and phytoplasmas that impact fruit tree, small fruit and grapevine production in North America and Hawaii. Pathogen isolates will be exchanged as necessary and with properly authorized permits. Newly developed molecular diagnostic reagents and procedures that allow better characterization of diverse fruit tree, small fruit and grapevine pathogens will also be distributed. 2) Develop and evaluate techniques to produce and maintain pathogen-free planting materials. Provide scientific expertise to stakeholders, as well as state and federal programs that disseminate planting materials. 3) Develop, optimize, and disseminate standard detection protocols to WCC-020 members, clean stock programs such as NRSP-5; FPMS (CA); Oregon Nursery Services, as well as state and federal (APHIS and CFIA) regulatory agencies. Compare the accuracy and reliability of rapid pathogen detection/identification techniques with graft-indexing protocols currently used in clean stock and regulatory programs. The successful implementation and acceptance of rapid pathogen detection systems will save commercial nurseries and governmental agencies considerable money, space and time. In addition to providing protection against foreign, exotic pathogens, new diagnostic capabilities will expedite the introduction of new planting materials and keep American and Canadian growers competitive in the world marketplace. 4) Identify and develop control programs for fruit tree, small fruit and grapevine viruses and phytoplasmas vectored by insects and nematodes. WCC-020 membership has always, and continues, to include entomologists, nematologists and plant pathologists. Productive and significant research on the biology of virus vectors requires interdisciplinary collaboration. Collaborative interactions between WCC-020 members will assess the impact of new vectors on the disease threat of Xylella fastidiosa in the Western region. Another project will determine the ability of Xiphinema thornei and X. utahense to transmit Cherry raspleaf virus. Several WCC-020 members from the United States and Canada (Eastwell, Halbrendt, Levy, Scott, Thompson, Uyemoto, Welliver) are participating in a new coordinated effort to development disease and plant management strategies to limit the spread and impact of Plum pox virus in North America. 5) Continue to conduct collaborative research on pathogens that impact common crops grown in geographically diverse areas. Disease management strategies developed for one type of pathogen or crop in one geographical area are often applicable to managing the disease in other areas. Collaborative efforts would thus save considerable time and resources by completing the research in a timely fashion and avoiding unnecessary duplication of research efforts.

Project Participation:

Include a completed Appendix E form

Educational Plan:

Annual meetings and written progress reports provide important forums for WCC-020 members to become acquainted with the most recent research accomplishments and emerging disease situations. Minutes of annual meetings are displayed at the Western Association of Agricultural Experiment Station Director's website (http://www.colostate.edu/Orgs/WAAESD/). Several WCC-020 members, including Howell, Kirkpatrick, Uyemoto, Rowhani, and Thompson, are participants in clean stock programs (NRSP-5; FPMS, CFIA) or federal regulatory agencies (APHIS, CFIA). Information presented at WCC-020 meetings is therefore rapidly assimilated and, where feasible, quickly integrated into these programs. Other state and federal regulatory personnel often attend WCC-020 meetings. The results of our collaborations are often transferred to clientele via Cooperative Extension Services, and WCC-020 members regularly publish the results of collaborative research efforts in refereed discipline oriented and popular press publications (see Publications in Appendix).

Governance:

Literature Cited:

Attachments:

[Petition.pdf]

Internal Linkages:

External Linkages:

Signatures:

s:/Ralph Cavalieri

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