WERA_OLD20: Virus and virus like diseases of fruit trees, small fruits and grapevines

(Multistate Research Coordinating Committee and Information Exchange Group)

Status: Inactive/Terminating

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SAES-422 Reports

Annual/Termination Reports:

[07/27/2001] [07/10/2002] [12/08/2003] [06/21/2004] [08/22/2005] [06/29/2006]

Date of Annual Report: 07/27/2001

Report Information

Annual Meeting Dates: 06/11/2001 - 06/13/2001
Period the Report Covers: 10/01/2000 - 09/01/2001

Participants

Cavalieri,Ralph(cavalieri@wsu.edu)-Washington State University;
Crosslin,Jim(jcrossli@tricity.wsu.edu)-Washington State University;
Damsteegt,Vern(damsteeg@ncifcrf.gov-USDA-FDWRU;
Eastwell,Ken(keastwell@wsu.edu)-Washington State University;
Foster,Joe(Joseph.A.Foster@USDA.gov)-USDA-APHIS;
Golino,Deborah(dagolino@ucdavis)-University of California-Davis;
Goodkind,David-USDA-PGQO;
Guerra,Lauri(LGuerra@agr.wa.gov-Washington State Department of Agriculture;Guzman,Tania-North Carolina State University;
Halbrendt,John(jmh23@psu.edu-Pennsylvania State University;
Heutte,Tom-USDA-PGQO;
Howell,Bill(bhowell@tricity.wsu.edu-Washington State University;
Hu,John(johnhu@hawaii.edu-University of Hawaii;
Hughes,Pam-Clemson University;
Johnson,Ray(johnsonrc@em.agr.ca)-Canadian Food and Inspection Agency;
Kinard,Gary(pgqogk@ars-grin.gov)-USDA-PGQO;
King,Steve(pgqok@ars-grin.gov-USDA-PGQO;
Larsen,Harold(Harold.Larsen@Colostate.edu)-Colorado Sate University;
Levy,Laurene-USDA-APHIS;
Mavrodieva,Vessela(vessela.a.mavrodieva@usda.gov)-USDA-APHIS;
Michelutti,Roberto(micheluttir@EM.AGR.CA)-Agriculture and Agri-Food Canada;
Milbrath,Gene(gmilbrat@oda.state.or.us)-Oregon Department of Agriculture;
Mock,Ray(pgqorm@ars-grin.gov)-USDA-PGQO;
Pesic-Vanesbroeck,Zvezdana-North Carolina State University;
Postman,Joseph-USDA-NCGR;Salih,Sarbagh-USDA-PGQO;
Scott,Simon-Clemson University;
Stone,Andy(andrew.stone@amedd.army.mil)-USDA-FDWRU;
Tiffany,Mike(miket@agdia.com)-Agdia;
Uyemoto,Jerry(jkyemoto@udcavis.edu)-USDA-UC, Davis;
Welliver,Ruth(rwelliver@state.pa.us)-Pennsylvania Department of Agriculture;

Brief Summary of Minutes

WCC-20 Minutes

June 11-13, 2001

Appalachian Fruit Research Station

Kearneysville, WV

The meeting began with introductions by WCC-20 2001 meeting coordinator Gary Kinard (USDA ARS) and welcome from Appalachian Fruit Research Station (AFRS) Research Leader Dariusz Swietlik. There were 31 in attendance (listed at end).

Discussions were held regarding the site for 2002 meeting. John Hu (University of Hawaii) volunteered to be local coordinator with the meeting held in Hawaii. Motion voted on and passed.

The death of Merritt Nelson was announced. A sympathy card was circulated to be sent to Nelson‘s family. A scholarship is being established in Nelson‘s honor. Also, George Nyland deceased in 2001. He was a founding member of WCC-20.

Ralph Cavalieri of Washington State University is the new administrative advisor to WCC-20. The WCC-20 is up for review, Ken Eastwell has written the proposal for the group‘s renewal. This will be voted on by Western research station directors. Ken has copies of the project re-write. Thanks to Ken for his efforts.

Bill Howell (Washington State University) asked to initiate a discussion of issues of impact on fruit tree stock imports by free trade agreements (FTAs). FTAs are changing the way pests are prevented from entering the country. Rules imposed on importers must be the same as rules for exchange within our country. For fruit trees and grapevines we will have to open our borders or impose mandatory certification programs for internal trade in the nursery industry. Bill has been asked by the northwest nursery industry to draft certification programs. One example of the current state of affairs is in California where 90% of free stone peaches are not virus certified. Bill mentioned the need to work with breeders to establish a paper trail for virus certification of new varieties.

Deborah Golino (University of California, Davis) continued the discussion noting that there are mandatory national certification programs in place in other countries. In the US we have the highest standard in the world with strict quarantine combined with extension and research programs. This high standard for voluntary programs works, but is not in keeping with international law. The North American Plant Protection organization (NAPPO) is working with Canada and Mexico on this. The US is still not prepared to go to the international community because we have no mandatory programs in place. She referred the group to an article by Joseph Foster on this subject.

Simon Scott (Clemson University) noted that plum pox virus (PPV) has revealed problems with the system in the Southeastern US. Ruth Welliver (Pennsylvania Department of Agriculture) added current practices do not encourage vigilance about maintaining an adequate paper trail for nursery stock. Growers are concerned about mandatory controls impinging on their freedom to propagate and trade stock. She mentioned a need for increased education in years when crises are not occurring to keep these problems at the front of their minds.

Joseph Postman (USDA APHIS) raised the question of strict controls limiting the availability of minor cultivars.

Gene Milbrath (Oregon Department of Agriculture) noted recent movement of ornamental Prunus has led to much interest in voluntary programs.

Ray Johnson (Agriculture Canada) mentioned that NAPPO is coordinating import and phytosanitary issues with between Canada, the US, and Mexico. NAPPO is looking to establish common standards. Five years ago rules were established for grapes. They are still working on standards using a very short list of pathogens. These standards are available on the NAPPO website.

Accomplishments

State Reports: Deborah Golino (UC Davis) reported on efforts to identify causes of sudden increase in severity and frequency of virus disease symptoms in grapevines in California vineyards. She hypothesized that some of the increase may have been due to shifts in rootstock planting preferences. Studies were undertaken to determine whether the decline of these vineyards was associated with virus infection, which viruses are involved, and to quantify the effects on these viruses on various rootstocks. Jerry Uyemoto (USDA ARS) reported detection of new graft-transmissible agents associated with grape rootstock stem lesion disease, and efforts to isolate and clone the causal agent of plum bark necrosis-stem pitting disease. Harold Larsen (Colorado State University) reported a new disorder called peach wart. Indexing tests are being performed by NRSP-5. Other projects involve peach latent mosaic viroid, peach mosaic, cherry rasp leaf virus, and phytoplasma. Ray Johnson (Agriculture Canada) gave an update on PPV found in southern Ontario and Nova Scotia. The same strain "D" type as the Pennsylvania isolates was identified. The Nova Scotia block was eradicated. Ontario has responded with quarantine in certain areas and block removal in other sites. John Hu (University of Hawaii) reported on an interesting etiological phenomenon in mealy bug wilt of pineapple. Plants infected with the virus alone show no symptoms and plants infested with mealy bugs but not infected with virus show no symptoms. The mealy bugs apparently inject some compound that makes the plant more susceptible to the virus. Sarbagh Salih (USDA ARS) gave an overview of the in vivo and in vitro therapy programs at the Plant Germplasm Quarantine Office (PGQO) in Beltsville MD. She outlined the time line for pome fruit therapy and gave a status report on future plans for therapy on Prunus. Ray Mock (USDA ARS) reviewed activities at PGQO including statistics on introductions and releases of the various small and tree fruit crops quarantined at Beltsville, as well as progress on building of the new facility there. Laurene Levy (USDA APHIS) is the acting director of the Plant Protection and Quarantine PPQ station at Beltsville. She reported on use of new technology for rapid in-field testing. She gave an account of some of the budget issues PPQ is facing with the new administration. Joseph Foster (USDA APHIS) discussed some problems and definitions involved in international trade of germplasm. He noted the perception of disparity resulting when we impose voluntary internal controls but require restrictions on imported germplasm. Joseph Postman (USDA ARS) presented an overview of the pear and other collections at the National Clonal Germplasm Repository in Corvallis OR. Highlights included pear blister canker viroid association with severe stony pit isolates, gooseberry vein banding virus found in other Ribes crops, and his research at the National Agricultural Library on their collection of 7000 pomological watercolors from the 19th century, documenting a diversity of fruit crop varieties. Gene Milbrath (Oregon Department of Agriculture) reported on blueberry scorch virus. Very little resistance in commercial cultivars. Concerns with increased acreage of blueberries, lack of certified stock. A pest alert for blueberry scorch is on their website www.odu.state.or.us Ruth Welliver (PA Dept of Agriculture) reviewed PPV monitoring and containment activities in Pennsylvania and the economics and politics of eradication. Some statistics: 18 positive blocks in 1999. 40 in 2001. 1159 acres destroyed to date. Cost of effort so far $30 million. Simon Scott (Clemson University) told about his efforts to work with the nursery industry in the Southeastern US on virus certification programs and some of the challenges encountered in changing the attitudes of an industry still using questionable practices in the trade, increase and marketing of nursery stock. Ken Eastwell (WSU) reported a virus-induced decline of sweet cherry associated with cherry leaf roll virus. Not sure of transmission. It is a nepovirus but no nematode vector identified. Also looking at cause of green crinkle. He reported on a grapevine virus survey to get a baseline of viral infections in Washington vineyards and isolation of a carlavirus associated with black death disease of Helleborus that was transmitted to other hosts with green peach aphids. Bill Howell (WSU) reviewed work on an ilarvirus of cherry, prunus dwarf virus. Some new cherry rootstocks are sensitive to PDV and PNRSV. A survey found varying degrees of sensitivity to PDV and PNRSV. He also reported an association of green crinkle in apple with ACLSV, ASPV and ASGV. Roberto Michelutti (Ag Canada) reported on his work indexing the Canadian clonal germplasm repository in Harrow. Vern Damsteegt (USDA ARS) presented highlights of his work on PPV. He noted that the strain D is actually a serogroup with some variation within the D epitope. He has PPV strain D in an herbaceous host and is working on producing antisera. He noted striking patterns of chlorosis and necrosis on P. tomentosa. He mentioned some differences between the European strain D and the Pennsylvania strain D such as production of lesions in quinoa. He also mentioned seedlings taken from PPV infected orchards showing mosaic symptoms but without finding any pathogens. The agent is graft transmissible. Zvezdana Pesic-Vanesbroeck (NC State University) gave an overview of NC State‘s indexing and micropropagation program for sweetpotato and strawberry. Dariusz Swietlik gave an overview of activities at AFRS including mechanical harvest technology, particle films and sugar esters for crop protection, natural product chemistry to combat forborne pathogens, transgenic and traditional breeding programs, new selection, and horticultural methods development. The group toured AFRS on July 12 and went on a field trip to Chrysalis Vineyards in Middleburg Virginia and to two PPV sites in Adams County Pennsylvania on July 13. Tony Wolf (Virginia Polytechnic Institute) gave a presentation on grapevine yellows phytoplasma at Chrysalis Vineyards. The group then traveled to Adams County Pennsylvania where Ruth Welliver arranged for the group to examine PPV symptoms on trees at two commercial orchards.

Publications

Impact Statements

Date of Annual Report: 07/10/2002

Report Information

Annual Meeting Dates: 05/16/2002 - 05/20/2002
Period the Report Covers: 10/01/2001 - 09/01/2002

Participants

Borth,Wayne(borth@hawaii.edu-University of Hawaii;
Chan-Haldebrendter,Catherine(chanhalb@hawaii.edu-University of Hawaii;
Crosslin,Jim(jcrossli@tricity.wsu.edu)-Washington State Univ.;
Ferreira,Steve(stephenf@hawaii.edu)-University of Hawaii;
Fitch,Maureen(mfitch@pbarc.ars.usda.gov)-Pacific Basin Ag. Res. Center/USDA;
Gaskill,Doug(dgaskill@hawaii.edu)-University of Hawaii;
Golino,Deborah(dagolino@ucdavis.edu)-University of California, Davis ;
Gonsalves,Dennis(dgonsalves@pbarc.ars.usda.gov)-Pacific Basin Ag. Res. Center/USDA;
Hu,John(johnhu@hawaii.edu)-University of Hawaii;
Kinard,Gary(pgqogk@ars-grin.gov)USDA-ARS Beltsville, Maryland;
Kirkpatrick,Bruce(bckirkpatrick@ucdavis.edu)-University of California, Davis;
Melzer,Mike(melzer@hawaii.edu)-University of Hawaii;
Michelutti,Roberto(michelutti@em.agr.ca)-Ag. & Agri-food Canada, Harrow, Ont.;
Naguwa,Melissa(mnaguwa@hawaii.edu)-University of Hawaii;
Neupane,Kabi(kabi@hawaii.edu)-University of Hawaii;
Perez,Eden(edenp@hawaii.edu)-University of Hawaii;
Pitz,Karen(pitz@hawaii.edu)-University of Hawaii;
Postman,Joseph(jpostman@ars-grin.gov)-USDA-ARS Clonal Rep., Corvallis, OR;
Rowhani,Adib(akrowhani@ucdavis.edu)-University of California, Davis ;
Schenck,Susan(sschenck@harc-hspa.com)-Hawaii Agric. Res. Center;
Schilder,Annemiek(schild@msu.edu)-Michigan State University;
Sether,Diane(sether@hawaii.edu)-University of Hawaii;
Song,Congfeng(songcf@bnjan.edu)-University of Hawaii;
Thompson,Dan(thompsonda@inspection.gov.ca)-CFIA, CPH, Canada;
Tiffany,Mike(miket@agdia.com)-Agdia, Inc., Elkhart, Indiana;
Zhu,Judy(jzhu@harc-hspa.com)-Hawaii Agric. Res. Center

Brief Summary of Minutes

The meeting was called to order by John Hu. Information on the meeting and field trip itineraries were presented and discussed.

Catherine Chan-Haldebrendt (U. of HI) provided an overview of Hawaiian agriculture. Farm revenues were estimated at about $570,000,000 with pineapple, sugarcane, and seed being the top three industries. She urged us to come back to Hawaii and spend money to help offset the recent drop in tourism!

Ralph Cavalieri, the WCC-20 Advisor, addressed the gathering via phone link from Pullman, WA. He informed us that the Committee has been renewed for 5 more years. He mentioned that moneys may become available for ?agri-security? programs, and that this is something the members should consider.

The site for next years meeting was discussed and debated. No firm plans were decided upon. Suggested sites included and University of Guelph, Colorado, and UC Davis. (After the meeting, John Hu discussed with Dr. Baozhong Meng, plant virologist at University of Guelph. Dr. Meng was interested in hosting the 2003 annual meeting.)

The minutes of last years meeting in Kearneysville, WV were distributed by Gary Kinard and accepted by the members. Jim Crosslin was selected as secretary of this year?s meeting.

Roberto Michelutti had photos from the last year?s meeting.

Field Trip, May 17, 2002, Oahu

The sites we visited included the Waimanalo Experiment Station where we observed banana bunch top virus (BBTV) symptoms. PRSV was also observed on nontransgenic papaya as compared to the excellent control of PRSV observed in transgenic ?Rainbow?. We also visited the Hawaiian Ag. Research Center, Kunia, where we say sugarcane, kava, papaya, coffee, and taro. We also visited a watercress operation not far from Pearl Harbor, where a phytoplasma disease is a problem. The next stop was a Dole pineapple production field near the north shore of Oahu where we saw the symptoms of pineapple mealybug wilt. All of us were impressed with the time and effort which is required to produce a pineapple crop.

Field Trip, May 20, 2002, Hawaii

We first visited the Pacific Basin Tropical Plant Genetic Resource Unit of USDA near Hilo. The research leader, Dr. Zee, showed us some of the collection of palm, guava, mountain apple, coffee, tea, papaya, breadfruit, ginger, and other crops. There was some ?beautiful? citrus tristeza virus too. Next stop was Mauna Kea banana plantation (no cameras allowed!!) where we saw a commercial banana operation. For a lunch stop, we went to over 6,000 feet on Mauna Kea and saw symptoms of a phytoplasma disease of the native Dodonea viscosa. A trip to Orchid Isle Dendrobiums followed where we saw a commercial orchid operation and the spotting caused by Cymbidium mosaic virus. Last stop was Volcani Isle Fruit Company, Kapoho (visit them at papayas.net) to see papaya and apple banana production fields.

Information compiled by Jim Crosslin and modified by John Hu

Minutes Attachment:

Attachment

Accomplishments

Steve Ferreira, U. of HI. Steve provided history of the work which produced transgenic papaya with resistance to papaya ringspot virus (PRSV). This work has allowed the continued production of papaya in areas where the virus made papaya production nearly impossible. The major cultivar now grown is ?Rainbow? and it has been well received by growers and consumers alike. He also mentioned ongoing work to identify delayed ripening genes for use in papaya and the use of consensus ?synthetic? genes in order to broaden the anti-PRSV activity. Maureen Fitch, Pacific Basin Ag. Res. Center, HI. Maureen discussed the breeding and clonal propagation of PRSV resistant papayas other than ?Rainbow? to meet the needs of other growing areas and markets. They are working on tissue culture procedures for clonal propagation of the desirable types. Susan Schenk, Hawaii Ag. Res. Center, HI. Sugarcane is widely infected around the world by Sugarcane Yellow Leaf Virus, a Polerovirus of the Luteoviridae family that produces leaf yellowing and plant growth reduction. It is transmitted by the sugarcane aphid, Melanaphis sacchari. A tissue blot immunoassay diagnostic technique allowed plantation surveys and determination of the extent of virus infection and the sugarcane cultivars infected. Certain cultivars were found to be resistant to infection and preliminary work indicates that resistance may be inherited. Breeding for resistance may thus be possible. The rate and spread of the virus within inoculated plants was also established. Related Saccharum species and several grain crops were also found to be susceptible to the virus, but to date no weed hosts have been found. Doug Gaskill, U. of HI. Doug discussed banana bunchy top virus (BBTV), which is vectored by the banana aphid in a persistent manner. The virus is widespread on Oahu, but not around Hilo on the island of Hawaii yet. Work is continuing on tissue culture systems, transformation, and regeneration of transgenic plants with resistance. Currently there are two lines that have remained symptom-free for 2 years. These were produced with a mutated REP gene of BBTV. Diane Sether, U. of HI. Diane discussed the dreaded pineapple mealy bug wilt and the associated viruses (PMWaV) and the impact of this disease on the pineapple industry in Hawaii. Two closteroviruses have been associated with this disorder, which also requires the presence of the vector mealy bug for development of severe symptoms. Axillary and apical buds could be a source of virus-free plants for in vitro propagation and establishment of clean pineapple fields. Eden Perez, U. of HI. Eden?s research focus is on the production of transgenic pineapple with resistance to PMWaV. Agrobacterium and gene gun-mediated approaches have been used. She also works on the evaluation of nematode resistance. Mike Melzer, U. of HI. Mike presented information on the molecular characterization of PMWaV 1 and 2. Double-stranded RNA served as source material for RT-PCR amplifications and cloning. The viruses show some sequence similarities to other mealybug-transmitted closteroviruses, such as grapevine leafroll associated virus 3. Wayne Borth, U. of HI. Wayne discussed his work on phytoplasma diseases of Dodonea and watercress. The Dodonea phytoplasma is related to Western X and the watercress yellows agent to aster yellows. Aster yellows phytoplasma has been detected infecting watercress on 11 farms on the island of Oahu. The aster leafhopper, M. quadrilineatus, has also been found at these farms. Both are recent introductions to the state of Hawaii, and together pose a significant threat to agriculture here. Jim Crosslin, Washington State Univ.-Prosser. Jim discussed the work in Washington on peach latent mosaic viroid, grapevine viruses, and virus diseases of sweet cherry. Cherry leafroll virus and little cherry viruses 1, 2, and 3 are of increasing importance. The testing and therapy services of NRSP-5 for phytoplasmas and viroids were discussed. Joseph Postman, USDA-ARS, Corvallis OR. The research Joseph discussed included evaluation of pear as a host of apple mosaic virus. The virus was not detected. Medlar was also tested as a host of apple chlorotic leafspot virus (ACLSV). Symptoms were produced on graft inoculated indicators. Other plants tested for viruses included Hawaiian strawberries, raspberries, and blueberries. Genetic resources of the collection being maintained at Corvallis were discussed. The virus indexing, virus therapy, and in vitro culture work we do at the USDA/ARS National Clonal Germplasm Repository helps to promote the improved national and international exchange of temperate fruit germplasm. Virus tested plant material is better able to obtain phytosanitary certification and meet the quarantine import regulations for the states and countries of germplasm requestors. Annemiek Schilder, Michigan State Univ. 1) Virus screening of table grapes (T. Zabadal, A. Schilder, and J. Gillett [MSU]). Tomato ringspot virus was found in declining table grape vines ?Marquis? and ?Vanessa? at the Southwest Michigan Research and Extension Center in Benton Harbor, MI, in 2000. The infection was confirmed with indicator plants and Ouchterlony double diffusion tests. These varieties were not known to be susceptible before. Dagger nematodes, Xiphinema spp., were also found in the soil at the site. An isolated mother block was established with selected vines from a noninfected site. Repeated testing has failed to detect any viruses in these plants and they now used for production of planting material. At the original site, experiments with ?Marquis? and ?Vanessa? on nematode-resistant rootstocks are underway. These vines are anticipated to remain virus-free. 2) Virus-tested blueberry program (P. Sood and R. Zinn [MDA]), and J. Gillett [MSU]). Two blueberry nurseries in Michigan are participating in the virus-free certification program for blueberries. Under this program, mother blocks were screened by ELISA for five viruses (blueberry shoestring virus, blueberry leaf mottle virus, tomato ringspot virus, tobacco ringspot virus, and peach rosette virus). All samples were negative and the plants were certified to be virus-free. 3) Virus-tested tree fruit program (P. Sood and R. Zinn [MDA]) The MDA is also actively involved in improving the quality of pome and stone fruit trees in MI through indexing of nursery stock at Hilltop Nurseries, Inc. in Hartford, MI. The nursery maintains 12,600 stone and pome fruit trees in four scion-wood orchards for certification of bud wood for virus-free status. All trees were indexed or ELISA-tested or both for apple chlorotic leaf spot, apple stem grooving, apple stem pitting, green ring mottle, prune dwarf, and prunus necrotic spot viruses. 4) Survey for blueberry scorch and shock viruses (P. Sood and R. Zinn [MDA]) Leaf samples (200 total) from fifty blueberry fields in Michigan were tested by ELISA for the presence of blueberry scorch virus and blueberry shock ilarvirus, which are at present only known to occur in blueberry-growing areas in OR, WA, and BC, Canada. All samples turned out to be negative and it is therefore assumed that these viruses are not present in Michigan. A quarantine program was established for all blueberry planting stock coming into MI to help protect the Michigan blueberry industry from these viruses. 5) Plum pox virus detection and diagnostics (P. Sood and R. Zinn (MDA), and A. Jones [MSU]). There are approximately 7,000 acres of stone fruit crops, excluding cherries, in MI. To help growers and crop consultants recognize plum pox virus, a Plum Pox Detection Guide was published and distributed. Inspections of peach, nectarine, apricot and plum orchards were carried out by the MDA as part of the National Plum Pox Virus Survey. Production, nursery, and research orchards were surveyed in 22 counties in Michigan in 2000 and 27 counties in 2001. In 2000, leaf samples from 34,638 trees were tested by USDA-approved ELISA for PPV strain D and other strains. In 2001, leaf samples from 92,484 trees were tested. All samples have been negative so far. Additional commercial orchards and nursery budwood trees will be tested for PPV in 2002. The MDA is currently working on a strategy to keep Michigan PPV-free. 6) Breeding cherries with resistance to viruses (A. Iezzoni [MSU], W. Howell [Washington]). Selections from the MSU cherry dwarfing rootstock breeding program have been screened for resistance to prunus necrotic ringspot virus and prune dwarf virus in Prosser, WA. Several resistant genotypes have been identified. 7) Isolation and characterization of a transcriptional promoter from blueberry red ringspot virus (R. Allison, C. Mecey-Smith, and J. Gillett [MSU]). The goal of this project is to isolate a promoter sequence from the DNA plant virus blueberry red ringspot virus (BRRV) for genetic modification of plants. The BRRV genome was cloned and sequenced. Seven promoter-like sequences were identified in the BRRV genome. Three of these were able to drive GFP expression in transgenic Arabidopsis thaliana, and one looked particularly promising. Currently, the other sequences are being tested for promoter activity. Assuming the promoter is functional as anticipated, it will be useful to University researches and licencees. 8) New fruit virology position The Department of Plant Pathology at MSU has requested a faculty position with an emphasis on applied research with an emphasis on small and tree fruit viruses. It is expected that this position will be filled in the next two years. Dennis Gonsalves, USDA, Pacific Basin Ag. Res. Center, HI. Dennis discussed the PPV survey currently underway in New York state, and evaluations of grape accessions for resistance to grapevine fanleaf virus (GFLV) and grapevine leafroll associated virus 3. Dennis has recently received a large grant for making transgenic papaya available to Third-world countries, such as Bangladesh, as a way of improving nutrition. Gary Kinard, USDA, Beltsville, MD. Gary discussed the work of the Plant Germplasm Quarantine Office. In the last year the facility has intercepted numerous pathogens including several apple viruses and phytoplasmas. Some Prunus samples were also infected with peach latent mosaic viroid (PLMVd) and Prunus necrotic ringspot (PNRSV) and prune dwarf (PDV) viruses. Numerous Prunus, Malus, and Pyrus samples are currently undergoing therapy at the facility. Dan Thompson, CFIA, Sydney, B.C. Dan?s presentation included information on host range studies of Canadian isolates of PPV. Prunus grandulosa was found to be a host. Tests were conducted to determine the best method of sampling for PPV detection in orchards. Distribution of PPV in infected trees was found to be erratic in some plum and peach trees. The national survey for PPV involved testing approximately 142,000 samples. Roberto Michelutti, Ag. Canada, Harrow, Ont. Roberto discussed the detection of numerous viruses of strawberries and raspberries. Raspberry bushy dwarf (RBDV) and tobacco streak (TSV) viruses were found. Several latent viruses were detected in apples, including ACLSV, apple stem grooving (ASGV), and apple stem pitting (ASPV) viruses. Biological and serological detection methodologies were compared. The survey for viruses infecting soybeans was discussed. Bean pod mottle virus (BPMV) was found for the first time. Deborah Golino, UC Davis. Deborah discussed the National Grapevine Importation Program and other activities of the Foundation Plant Materials Service (FPMS). The program includes stocks of grape, strawberry, pistachio, sweet potato, roses, and some Prunus. Grapes are tested and certified for GVFLV, TomRSV, GVLR, and corky bark, among other viruses. Custom PCR testing for several grape viruses are available. Tested and certified materials are available on a fee basis to nurseries, etc. Adib Rowhani, UC Davis. Adib presented information on the detection of a new grapevine leafroll associated virus (GVLRaV-9). The presence of new graft-transmissible agents (GTAs) in the grape collection was discussed. Information on almond union mild etch (AUME), a genetic disorder, was presented. His research projects are focusing on characterizing of new viruses in grapevine or those which are partially characterized. This information will help in classification of the viruses under investigation and understanding of their etiology and epidemiology and their possible natural vectors. In addition, development of sensitive and reliable molecular methodologies for their detection will greatly facilitate their detection and elimination in commercially valuable material. Bruce Kirkpatrick, UC Davis. Bruce discussed a wide range of research efforts on phytoplasmas and phytoplasma-induced diseases. Included were the genomic sequencing efforts on phytoplasmas and the Pierce?s disease organism, Xylella. The biology of vector species of leafhoppers was discussed.

Publications

Impact Statements

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
WCC-020 is a unique network that encourages interaction among regulatory, research, and extension personnel
WCC-020 has been effective in providing information and solutions to disease problems and transferring technologies between states and across provincial lines
WCC-020 has fostered the exchange of new and recent information on research findings and regulatory concerns and helps researchers keep current with rapid developments in detection technology
Advances in detection and virus treatment technologies during the late 1980's and the 1990's have been impressive and extremely useful
The dependence of quarantine and certification programs and research programs on these techniques has increased dramatically
Detection tools are at the heart of clean nursery stock programs that have been implemented by several states and British Columbia
These programs have greatly improved the quality of orchards that use certified pathogen-tested nursery stock and contribute to the reduction in new diseases entering regions
New insights into the etiology of several diseases of fruit trees and grapevines have been essential in formulating quarantine regulations based on the most recent research findings

Date of Annual Report: 12/08/2003

Report Information

Annual Meeting Dates: 11/17/2003 - 11/19/2003
Period the Report Covers: 10/01/2002 - 09/01/2003

Participants

Participants Attachment:

Attachment

Brief Summary of Minutes

Part I. Opening Remarks and Business Meeting:

John Hu, chair of WCC20, called the meeting to order.

Ralph Cavalieri, WCC20 Administrative Advisor, welcomed participants. He mentioned that reporting was the only administrative requirement for WCC20 this year. Ralph discussed the need to let Experiment Station Directors know if germplasm and NRSP5 are important to their research, or funding for these programs through CSREES will disappear.

It was announced that Adib Rowhani has agreed to chair and host WCC20 next year, holding the meeting in Davis CA in the third week of May. NRSP5 will meet jointly with WCC20 in Davis.

Special thanks to Ralph Scorza, Ruth Welliver, John Halbrendt, and the NE1006 (Plum Pox) planning committee for proposing the joint meeting with their group this year.

Special thanks to Ruth Welliver for taking notes and preparing the annual report of the 2003 annual meeting.

Special recognition and thanks to Dr. Baozhong Meng, who worked hard to set up and organize the meeting and field trips for May 2003, that were so sadly cancelled due to potential problems with SARS. Our thanks to Dr. Meng and his colleagues for the effort expended.

Other Meeting Activities:

Joint meeting of NE1006, November 17-18, 2003

Many WCC20 attendees also participated in the NE1006 meeting. NE1006 is the project on Eradication, Containment and/or Management of Plum Pox Disease (Sharka). In this meeting, talks were given that summarized survey data for work in both the United States and Canada. Research reports were presented on host range, strain characterization, transmission, epidemiology, and detection of virus. Work developing transgenic resistance and its underlying mechanism was described. An outline of the regulatory process surrounding PPV as a select agent under the Ag Bioterrorism Prevention Act of 2002 was provided. Finally, research information transfer via university extension projects and certification initiatives were discussed. Dr. Michel Ravelonandro, from INRA, Bordeaux, France, was an invited speaker who presented an overview of plum pox virus in Europe. Approximately 100 people participated the NE1006 annual meeting.

Tour: A tour of the Appalachian Fruit Research Station was offered to all interested parties.

Accomplishments

Part II. State Reports Dan Thompson, CFIA Centre for Plant Health, Sydney, B.C. During the NE1006 portion of the meeting, Dan presented an update on host range studies for the Canadian isolates of PPV. During WCC20, he reported on work to optimize a system for detection of fruit tree phytoplasmas by PCR, utilizing the same RNA extraction also used for virus PCR tests. Dan found the test fairly reliable from early June through October, using either RNA or DNA extraction. Roberto Michelutti, Agriculture and Agri-Food Canada Clonal Genebank, Harrow, Ontario, reported on testing for viruses in Fragaria, Rubus, Malus, Pyrus, and Prunus in their collection. Two years of plum pox screening have yielded all negative results. In collaboration with colleagues in Spain and Italy, Roberto used a tissue printing assay for PLMVd, hop stunt viroid, and PPV. Deborah Golino, Foundation Plant Services, UC-Davis, showed work on experimental transmission of two closteroviruses (grapevine leafroll-associated Virus 5 and 9) by Longtailed Mealybugs. She discussed the complexity of the system and the difficulty in identifying singlely-infected plants. She also mentioned that a relatively new mealybug species to CA (the vine mealybug) is changing the dynamics of the system. Jerry Uyemoto, USDA-ARS, UC-Davis gave an update on the rootstock genotypes that react with Redglobe virus (GLRaV-2 RG). The virus kills five rootstocks within two dormancy periods. Jerry recommends that, to properly monitor for virus disease agents, numbers of biological indicators should increase rather than decrease. In tree fruits, Jerry showed three separate instances of the occurrence of Cherry Virus A in CA, each in combination with other viruses and with different symptoms. He also described a Bing cherry with cherry necrotic rusty mottle foveavirus, and graft-transmissible Plum Bark Necrosis Stem Pitting on black beaut. John Hu, from the University of Hawaii, presented his work on survey and control of Citrus Tristeza Virus (CTV) in Hawaii. CTV isolates have been collected and characterized at the serological and molecular level. Significant strain diversity exists in Hawaii: variation within and between groups is 91% with HI and foreign alignments, even excluding outliers from the analysis. Development of transgenic plants with broad resistance is a current goal, using a chimeric transgene approach in the Mexican Lime regeneration system. Johns group is also evaluating local CTV strains as cross protection candidates, and has identified several promising mild isolates. Harold Larsen, Colorado, discussed local industry changes the apple industry is shrinking in size; peach now #1, apple #2, wine grape #3 in acreage. Harold is now 65% viticultural support powdery mildew in grape and bloom delay in grapes. Increasing interest in sweet cherries. Have cherry raspleaf (in peach, cherry, apples). Would like to see development of rootstocks with resistance to CRLV acquisition. Harold showed images of grape displaying a necrotic vein symptom of unknown etiology, as well as some suspected chemical injury and other pests in grape. Peach mosaic and peach wart have not been seen in recent years. Ray Mock, USDA-ARS Plant Germplasm Quarantine Office, Maryland, described administrative changes in their unit, staffing shortages, and an update on their building project. This year, imports received were very near their maximum capacity, and many releases were made, with a large number of samples still in process in therapy and testing via standard regimen. The unit intercepted disease agents in pome fruits, stone fruits, and small fruit. The molecular research lab, under the guidance of Dr. Li, is developing new methods for testing, currently working with CGRMV and CNRMV in Prunus, blackcurrant reversion and gooseberry vein banding virus in Ribes. Ruhui Li USDA-ARS Plant Germplasm Quarantine molecular research lab, Maryland, provided a research report on detection of cherry green ring mottle and cherry necrotic rusty mottle foveavirus by rt-pcr. The original objective of the research was to investigate replacement of biological assay with pcr. Using sequences from both viruses, Dr. Li developed consensus primer sequences for the two viruses, and developed a fast, simple, and reliable RNA prep method. Ramon Jordan, USDA-ARS, Beltsville, Maryland, mentioned that he was working to identify potyviruses that react in the Durviz PPV ELISA test. Preliminary evidence points to a Tulip-breaking-like virus in lily, tested originally by John Halbrendt in Pennsylvania, that cross-reacts. Annemiek Schilder, Michigan State Univ., reported on fruit virology activities in Michigan. Annemiek provides diagnostic support for small fruit growers. Blueberry disease symptoms have increased in 2003: shoestring predominant, with some tobacco ringspot, stunt suspected but not confirmed, and virus-like symptoms cold injury in blueberries, potato leafhopper in raspberries. Tobacco ringspot finds in table grape planting stock initiated a program of screening mother blocks and propagating virus-free planting material. Virus-free blueberry nursery program is also available and expanding. Annemiek summarized MI Dept. of Agriculture program testing pome and stone fruit nursery stock, a Michigan breeding program for virus tolerance in sweet cherries, a research program on virus-mediated resistance in cherries, work with the blueberry red ringspot promoter as an alternative to CaMV 35S, and development of a new IPM scouting guide for grape. Gene Milbrath, OR Department of Agriculture, summarized work in Bob Martins lab, Corvallis. All blueberry coming into state must be tested for blueberry scorch, in an effort to prevent more aggressive strains from becoming established. Bob is investigating possibility of blueberry scorch in cranberries. He is also working with whitefly-transmitted viruses in small fruits blackberry yellow vein-associated virus appears to have been distributed across southeast from Arkansas breeding program, beet pseudo-yellows virus in blackberries from southeast and in strawberries from CA and MD. Aphid-borne viruses in strawberry from NW cause severe decline in one variety of strawberry that was developed as a tolerant variety. ODA plum pox survey has concentrated in orchards around nurseries, rather than nurseries themselves, in 2003; did special pumiselect sampling as part of traceback work for a positive in PA. All PPV testing of Oregon material negative. 26 nurseries in certification testing for ilars and ToRSV. Becoming a large ornamentals program with fruit trees declining. Did do cherry leafroll survey in Oregon cherry orchards. Some suspicious symptoms, but all tested negative. Simon Scott, Clemson University, South Carolina, gave a status report on work with Ta Tao varieties and their associated viruses and viroids. He is attempting to tease out the components of the system that result in bloom delay in Ta Tao and related Chinese genetic resources. So far, various combinations of Asian Prunus Latent Virus, perhaps several other foveaviruses, peach latent mosaic viroid, and apple chlorotic leafspot virus have been implicated. Simon is also experimenting with Okinawa rootstock as an indicator plant for various Prunus viruses. During NE1006 portion of meetings, Simon also presented information on PPV sampling and testing of fruit all negative. John Halbrendt, Pennsylvania State University, and Ruth Welliver, PA Dept. of Agriculture, both presented information on 2003 PA plum pox work during the NE1006 portion of the meeting. In addition, they mentioned an apple decline situation they are investigating. Bill Howell, NRSP5, Washington state (with input from Laurri Guerra, WA Dept. of Agriculture), discussed the emergence of Cherry Leafroll Virus decline disease in sweet cherry. Disease can be even more severe in mixed infection with ilarviruses. Washington state fruit commission worked to clean up orchards through educational/survey program involving extension, fruit packing warehouse fieldmen, and growers. Removing diseased trees must use herbicide to detect root grafts (see herbicide damage the next spring), and insecticide to kill vectors before removing trees in summer time. Bill described the four different viruses associated with little cherry disease new isolate similar to the German one, now causing problems in the U.S. Other viruses they are seeing include cherry rusty mottle foveavirus, another foveavirus causing pitting on montmorency interstock, and a third foveavirus just being characterized. Peach latent mosaic viroid update: peach blotch disease (?) may be PLMVd severe strain (mild strains dont cause symptoms). Lauri ran a CAPS project to test all mother trees, peach and nectarine 50% had PLMVd. Will repeat in a few years, to see if flushing system with clean material works to start cleaning this up. Apple green crinkle disease is getting to be a big problem. Only expressed in fruit during years with prolonged, cool Spring. Causal agent not clear, probably because it is a multi-component complex. Bill did differential heat treatments on green crinkle wood, to try to separate out agents. This year was first year with fruit. One tree showing symptoms has no ACLSV, which was their prime suspect originally. ACLSV associated diseases in Prunus are more common these days prune plums, incompatibility in cherry, brown line, gumming on trunks, brown streaks. Lauri described disease findings in certified mother blocks. Bill mentioned the new paper that addresses economic impact of clean stock programs. He also mentioned a new grape foundation program for WA, OR, ID, BC at WSU station. John Hu, WCC20 chair for 2003, thanked all the presenters and participants (about 30 people), and made some closing remarks.

Publications

Cembali, T., R.J. Folwell, P. Wandschneider, K.C. Eastwell, and W.E. Howell. 2003. Economic implications of a virus prevention program in deciduous tree fruits in the US. Crop protection 22:1149-1156. Marini, D. B., Rowhani, A., and Uyemoto J. K. Discovery of a new graft-transmissible agent causing bark necrosis and stem pitting in ‘Black Beaut‘ plum and symptoms in other Prunus species and varieties. California Agriculture 56(3):108-111. 2002. Uyemoto, J. K., Buylluck, III, L. R., Pethybridge, Sarah, McCorkell, Bruce, and Asai, W. K. Horizontal spread of ilarviruses in young trees of several peach cultivars. Plant Dis. 86:75-77. 2003.

Impact Statements

Much of the research of WCC20 participants, facilitated by interaction at WCC20 meetings, is immediately and directly applied to improve clean stock programs or to justify establishment of new clean stock programs.
The economic impacts of clean stock programs on plant propagators, fruit growers, and consumers was recently quantified, amounting to over $200 million annually.
Efforts of the group to improve detection and elimination of viruses and virus-like agents entering the continent on infected plant material will result in savings to pest detection and control programs (such as the $40 million plum pox eradication program ongoing in Pennsylvania).
Impacts of transgenic resistance development is also easily seen in the success of the transgenic papaya work, bringing new life to Hawaiis papaya industry, and now being applied to systems such as citrus tristeza and plum pox virus.

Date of Annual Report: 06/21/2004

Report Information

Annual Meeting Dates: 05/17/2004 - 05/19/2004
Period the Report Covers: 10/01/2003 - 09/01/2004

Participants

Carrouche,Emilie(ecarrouche@ucdavis.edu)-FPS/UC-Davis, Davis, CA;
Cavalieri,Ralph(cavalieri@wsu.edu)-Washington State University, Pullman, WA;
Cunningham,Mike(macunningham@ucdavis.edu)-FPS/UC-Davis, Davis, CA;
Eastwell,Ken(keastwell@wsu.edu)-Washington State University, Prosser, WA;
Golino,Deborah(dagolino@ucdavis.edu)-FPS/UC-Davis, Davis, CA;
Guerra,Lauri(lguerra@mail.prosser.wsu.edu)-Washington Department of Agriculture, Prosser, WA;
Horner,Mary(mhorner@hortresearch.co.nz)-HortResearch, New Zealand;
Howell,Bill(wehowell@wsu.edu)-Washington State University, Prosser, WA;
Hu,John(johnhu@hawaii.edu)-University of Hawaii, Oahu, HI;
Johnson,Ray(johnsonrc@inspection.gc.ca)-CFIA-Sidney, British Columbia;
Kinard,Gary(pgqogk@ars.grin.gov)-USD-ARS, Beltsville, MD;
Kirkpatrick,Bruce(bckirkpatrick@ucdavis.edu)-UC-Davis, Davis, CA;
Lima,Mirtes(mflima@ucdavis.edu)-UC-Davis, Davis, CA;
Michelutti,Roberto(micheluttir@agr.gc.ca)-Ag-Canada, Harrow, Ontario;
Osman,Fatima(fmosman@ucdavis.edu)-UC-Davis, Davis, CA;
Rosa,Christina(crosa@ucdavis.edu)-UC-Davis, Davis, CA;
Rowhani,Adib(akrowhani@ucdavis.edu)-FPS/UC-Davis, Davis, CA;
Sim,Sue(stsim@ucdavis.edu)-FPS-UC-Davis, Davis, CA;
Scott,Simon(sscott@clemson.edu)-Clemson University, Clemson, SC;
Sioddard,Scott -UC Cooperative Extension;
Thompson,Dan(thompsonda@inspection.gc.ca)-CFIA, Sidney, British Columbia;
Tiffany,Mike(miket@agdia.com)-Agdia, Inc., Elkhart, IN;
Uyemoto,Jerry(jkuyemoto@ucdavis.edu)-USDA-ARS, Davis, CA;
Pesic-Vanesbroeck,Zvezdana(zvezdana_pecis@ncsu.edu)-NC State University, Raleigh, NC;

Brief Summary of Minutes

Minutes Attachment:

Attachment

Accomplishments

Accomplishments reported from different states were in general in three different categories. 1. Disease detection and survey. Reports from several states and Canada indicated that the molecular diagnostic tests for number of different viruses have been developed and/or improved. Sampling procedures and preparation also have been optimized for number of viruses of horticultural crops. Some of the viruses which were studied are Plum pox virus (PPV); Citrus tristeza virus (CTV); Grapevine leafroll associated virus (GLRaV) types 1, 2, 3 and 9; Pineapple mealybug wilt associated virus (PMWaV) 1, and 2. In particular the ELISA detection and distribution of PPV in dormant scion were studied and found that buds taken from field grown trees along with bark tissue from the basal end of the stick had highest virus titer. National PPV survey of 73,000 samples collected from Ontario and Nova Scotia was conducted and positive samples were found. The positive samples were infected with PPV-D strain. The same survey was conducted at the Clonal Genebank at Harrow, Ontario, and no PPV infections were found. 2. Reports of new viruses and other related research. Reports from several states and Canada indicated the discovery of new viruses or occurrence of known viruses in an area for the first time. These new viruses included: GLRaV-9, another virus in grapevine leafroll disease complex in family Closteroviridae, an unknown agent from black current in Canada showing virus-like symptoms on host plants, continued work on characterizing PMWaV 1 and 2 in Hawaii and discovery of two more potentially wilt associated viruses called PMWaV 3 and 4. Some known viruses were reported to be occurring in certain region for the first time. These viruses included: Grapevine rupestris vein feathering virus, Cherry virus A (CVA), Cherry necrotic rusty mottle virus (CNRMV), and Apple chlorotic leaf spot virus (ACLSV) in California. Other reported research accomplishments were, the continuation of the investigation of cross protection of cherry trees to rugose mosaic using a mild strain of PNRSV; Continued work on the effects of peach latent mosaic viroid on 5 peach and nectarine cultivars; characterization of Cherry rasp leaf virus (CRLV) and production of antibodies for its detection; continued work on graft incompatibility of cherry trees on Gisela 6 rootstock and possibility of involvement of ACLSV. 3. Other reports. Report from Canada Food Inspection Agency‘‘s Center for Plant Health described the maintenance of their virus-tested repository and their therapy program for grape varieties and rootstocks. This program also tests for strawberry and blueberry materials. A report from Foundation Plant Services program at UC Davis and its mission and function. Report on certification and micropropagation program at NC State that handles blueberries, blackberries, strawberries and sweet potatoes. Report from South Carolina on the status of the certification program for the southeastern peach industry. An update on NRSP5 program.

Publications

Impact Statements

Improvement of clean stock programs by improving new disease detection methods which have an impact of hundreds of millions of dollars on fruit tree growers.
Improvement of disease detection and elimination procedure for exotic pathogens in quarantine materials.
Development of transgenic plants resistant to viruses, e.g., papaya plants resistant to PRSV, which have saved the papaya industry in Hawaii and some other countries.

Date of Annual Report: 08/22/2005

Report Information

Annual Meeting Dates: 05/16/2005 - 05/18/2005
Period the Report Covers: 06/01/2004 - 05/01/2005

Participants

Ralph Cavalieri, Washington State University, Pullman, WA;

Ken Eastwell, Washington State University, Prosser, WA;

Raymond G. Mock USDA, ARS, Fruit Laboratory, Plant Germplasm Quarantine Office;

Lauri Guerra, Washington Department of Agriculture, Prosser, WA;

Mary Horner, HortResearch, New Zealand;

Bill Howell, Washington State University, Prosser, WA;

John Hu, University of Hawaii, Oahu, HI;

Roberto Michelutti, Ag-Canada, Harrow, Ontario;

Adib Rowhani, FPS/UC-Davis, Davis, CA;

Simon Scott, Clemson University, Clemson, SC;

Dan Thompson, CFIA, Sidney, British Columbia;

Mike Tiffany, Agdia, Inc., Elkhart, IN;

Zvezdana Pesic-Vanesbroeck, NC State University, Raleigh, NC

Brief Summary of Minutes

Please see attached file to include information on the following:

Virus and virus like diseases of fruit trees, small fruits and grapevines
2005 Annual Meeting - Minutes
JC Raulston Arboretum, NCSU, Raleigh, NC
May 16-18, 2005

I. Opening Remarks;
II. State Reports;
III. Business meeting;
IV. Other activities

In addition to the 2005 Report for the WCC 20 Meeting titled:

USDA-ARS Fruit laboratory Plant Germplasm Quarantine Office Pome, Stone, Small Fruit, and Molecular Diagnostic Programs
Beltsville, MD
May 16-18, 2005

Minutes Attachment:

Attachment

Accomplishments

Repeated vegetative propagation of sweet potatoes had resulted in the accumulation of viruses with resulting declining production after 7 years, and resulting loss of market share. Similarly, bacterial and fungal diseases of strawberry introduced from outside of NC impeded production. A micropropagation unit was established at North Carolina State University to produce virus-tested material for sweet potato and strawberry propagation. Plant Germplasm Quarantine Office of USDA-ARS and the National Research Support Project 5 have major beneficial impacts on the production objectives for stone, pome, and small fruits in the United States by providing virus-tested material to researchers and to industry. Virus detection methods are being enhanced through the cooperative efforts of several researchers associated with WERA-020, such as the recent development of a robust molecular assay for a virus associated with grapevine leafroll disease, but escaped detection by other serological or RT-PCR detection methods. A Southeast Budwood Program has been created that is supported by South Carolina, Georgia and three major nurseries in Tennessee. This certification program was initiated in 2000 in response to concerns about Plum pox virus (PPV), but all trees in this program are now tested PPV, as well as the Ilarviruses that contribute to early loss of production in peach orchards. A research and observation program for developing and monitoring Citrus tristeza disease resistance in citrus has been established in Hawaii. An industry sponsored program was launched in Washington State to detect and remove cherry trees infected with Cherry leafroll virus. The survey was funded by industry and operated through the chemical and fruit packing houses to optimize the use of individuals that are frequently in the orchards. The survey was accompanied by an intense educational program to increase the awareness to viruses and their negative impact on production. In 2004 the Canadian Plum pox virus (PPV) eradication program was given an $85 million seven year extension. The program is based on finding and removing all the PPV infected trees and replanting with clean trees. Cherry rasp leaf virus is one of the most prevalent fruit viruses in Colorado. Cherry rasp leaf virus infections continue to appear in newer sweet cherry blocks around age 6-10 years. However, sweet cherry acreage is below 300 acres for the state and production value likely is less than $150,000. Growers have found that plantings on Colt rootstock typically don't begin to exhibit symptoms until around year 9 or 10 or sometimes later, while plantings on other rootstocks begin to show symptoms around year 4 -6. There is interest among growers to look at cherry rootstock and interstem combinations to assess CRLV resistance for sweet cherries. Tentative plans have been made for next spring to initiate a greenhouse pot trial using Bing / Z-interstem / Citation RS trees (to be provided by Dave Wilson Nursery).

Publications

Thompson D. 2005. Practical Applications of the Plum Pox Virus Standard. NAPPO Newsletter, June, 2005. Ian McDonnell ed. North American Plant Protection Organization. Alkowni R, Rowhani A, Daubert S, Golino D. 2004. Partial characterization of a new ampelovirus associated with grapevine leafroll disease. J. Plant Pathol. 86:123-133. Newman K, Almeida RPP, Purcell AH, Lindow S. 2004. Cell-cell signaling controls Xylella fastidiosa interactions with both plants and insects. Proc. Nat. Acad. Sci. 101:1737-1742. Almeida RPP, Mann R, Purcell AH. 2004. Xylella fastidiosa cultivation on a minimal defined medium. Curr. Microbiol. 48:368-372. Purcell AH, Okano K. 2004. Effects of sublethal doses of imidacloprid on vector transmission of Xylella fastidiosa. Pages 146-149 in Proceedings of Pierce's Disease Research Symposium, Coronado, CA, Dec. 7-10, 2004. Purcell AH, Curley CM. 2004. Effects of chemical milieu on attachment, aggregation, biofilm formation, and vector transmission of Xylella fastidiosa strains. Pages 224-226 in Proceedings of Pierce's Disease Research Symposium, Coronado, CA, Dec. 7-10, 2004. Purcell AH, Almeida RPP. 2004. Role of bacterial attachment in transmission of Xylella fastidiosa by the glassy-winged sharpshooter, and other factors affecting transmission efficiency. Pages 227-230 in Proceedings of Pierce's Disease Research Symposium, Coronado, CA, Dec. 7-10, 2004. Purcell AH, Lindow S, Baccari C. 2004. A screen for Xylella fastidiosa genes involved in transmission by insect vectors. Pages 231-233 in Proceedings of Pierce's Disease Research Symposium, Coronado, CA, Dec. 7-10, 2004. Purcell AH, Lindow S, Wistrom C. 2004. Patterns of Xylella fastidiosa infection in plants and effects on acquisition by insect vectors. Pages 234-237 in Proceedings of Pierce's Disease Research Symposium, Coronado, CA, Dec. 7-10, 2004. Almeida RPP, Wistrom C, Hill BL, Hashim J, Purcell AH. 2005. Transmission of Xylella fastidiosa to dormant grapevines. Plant Dis. 89:419-424. Publications in Press (proofs returned) Wistrom C, Purcell AH. 2005. The fate of Xylella fastidiosa in vineyard weeds and other alternate hosts in California. Plant Dis. 89:[in press 6-05] Almeida RPP, Purcell AH. 2005. Vector transmission of Xylella fastidiosa: applying fundamental knowledge to generate disease management strategies. Ann. Entomol. Soc. Am. [in press 6-05] Bressan A, Purcell AH. 2005. Effect of benzothiadiazole on transmission of X-disease phytoplasma by the vector Colladonus montanus to Arabidopsis thaliana, a new experimental host plant. Plant Dis. 89:[in press 7-05]

Impact Statements

Currently, 45,000 acres of sweet potato valued at $60M are planted with material derived from the NCSU certification program.
The strawberry program at NCSU develops plants that are transferred to certified nurseries that are required to grow certified material only, and from here, the plants are distributed throughout the southeast.
An effective quarantine program encourages compliance with federal regulations regarding movement of germplasm and diminishes the temptations to smuggle plant material into the United States.
Therapeutic methods to eliminate pathogens can salvage potentially valuable germplasm.
Improved detection methods for quarantine pathogens can reduce the time germplasm is held in quarantine, as well as improve the reliability of the testing programs.
Quarantine programs intercept new or emerging pathogens or strains/isolates of a pathogen that may threaten US agricultural security.
The Southeast Budwood Program currently includes 40-50 varieties of commercial interest, most of which are unique to southeast peach production.
From a national perspective, Hawaii is in a unique position to develop and test control strategies for CTV. Such control strategies would not only be beneficial to Hawaii`s citrus industry, but also other citrus-producing regions that are threatened by CTV and the BrCA.
Cherry leafroll virus is a destructive virus of sweet cherry trees and has recently been detected in the Northwestern US fruit production areas. The extent of disease spread has been delineated and many infected trees have been removed. In response to this program, some County agencies also established and funded virus control programs.
A database of plant species that are susceptible to Plum pox virus is being developed. Knowledge of which plant species are hosts of PPV is critical to accomplish this goal.

Date of Annual Report: 06/29/2006

Report Information

Annual Meeting Dates: 05/08/2006 - 05/10/2006
Period the Report Covers: 06/01/2005 - 05/01/2006

Participants

Rodrigo Almeida, "rodrigo@nature.berkeley.edu" - UC Berkeley;
Ralph Cavalieri, "cavalieri@wsu.edu" - Washington State University;
Brenda Conley, "conleyb@inspection.gc.ca" Canadian Food Inspection Agency;
Ken Eastwell, "keastw@tricity.wsu.edu" - Washington State University;
Blake Ferguson, "fergusonb@inspection.gc.ca" - Canadian Food Inspection Agency;
Violet Galvin, "galvinv@inspection.gc.ca" - Canadian Food Inspection Agency;
Deborah Golino, "dagolino@ucdavis.edu" - UC Davis;
Charlene Green, "greenc@inspection.gc.ca" - Canadian Food Inspection Agency;
Lauri Guerra, "lguerra@prosser.wsu.edu" - Washington State University;
John Halbrendt, "jmh23@psu.edu" - Pennsylvania State University;
Bill Howell, "bhowell@tricity.wsu.edu" - Washington State University;
John Hu, "johnhu@hawaii.edu" - University of Hawaii;
Delano James, Gayle Jesperson, "Gayle.Jesperson@gov.bc.ca" - BCMAFF;
Ray Johnson, "JohnsonRC@inspection.gc.ca" - Canadian Food Inspection Agency;
Gary Kinard, "pgqogk@ars-grin.gov" - USDA, ARS;
Bruce Kirkpatrick, "BCKIRKPATRICK@ucdavis.edu" - UC Davis;
Chuck Lemmon, "clemmon@inspection.gc.ca" - Canadian Food Inspection Agency;
Roberto Michelutti, "micheluttir@agr.gc.ca" - AAFC;
Thierry Poiré, "poiret@inspection.gc.ca" - Canadian Food Inspection Agency;
Joe Postman, "jpostman@ars-grin.gov" - USDA, ARS;
Hélène Sanfaçon, "SanfaconH@agr.gc.ca" - AAFC;
Annemiek Schilder,"schilder@msu.edu" - Michigan State University;
Dan Thompson, thompsonda@inspection.gc.ca -Canadian Food Inspection Agency;
Mike Tiffany, "miket@agdia.com" - Agdia;

Brief Summary of Minutes

For photos of the participants at this meeting please contact eyeates@wsu.edu. They are in .tif format.

Minutes Attachment:

Attachment

Accomplishments

1. Viruses involved in the pineapple mealybug wilt disease and their biology have been determined. This was critical for the development and incorporation of cultural strategies, screening technologies at the tissue culture or propagation level, genetic engineering for virus resistance, and pest control including ant and mealybug control in pineapple production. 2. Transgenic plums (Prunus domestica) have been engineered to provide silencing of the Plum pox virus genome, and hence resistance to this virus. 3. It was postulated that infection of a transgenic plant by a virus unrelated to the virus to which the plant is resistant may result in a loss of resistance; this could present a major limitation in the utilization of resistance based on this technology. It was demonstrated that Tomato ringspot virus could not revert already established gene silencing, one of the underlying principles of genetically engineered resistance to viruses. 4. Hemagglutinin was identified as an important gene involved in the pathogenicity of Xylella fastidiosa.

Publications

Li, R., R. Mock. 2005. An improved reverse transcription-polymerase chain reaction (RT-PCR) assay for the detection of two cherry flexiviruses in Prunus spp. Journal of Virological Methods. 129:162-169. Martin, R.R., K.C. Eastwell, A. Wagner, S. Lamprecht, and I.E. Tzanetakis. 2005. Survey for viruses of grapevine in Oregon and Washington. Plant Disease. 89:763-766. Perez, E.Pp, D.M. Sether, M.J. Melzer, J.L. Busto, C. Nagai, and J.S. Hu. 2005. Characterization and control of pineapple mealybug wilt associated Ampeloviruses. Acta Horticulturae. 702:23-27. Sether, D.M., M.J. Melzer, J.L. Busto, F. Zee, and J.S. Hu. 2005. Diversity and mealybug transmissibility of Pineapple mealybug wilt associated viruses found in pineapple. Plant Disease. 89:450-456. Tzanetakis, I.E., J. Postman, and R.R. Martin. 2005. Characterization of a novel member of the family Closteroviridae from Mentha spp. Phytopathology. 95:1043-1048. Tzanetakis, I.E., J. Postman, and R.R. Martin. 2005. A member of the Closteroviridae from mint with similarities to all three genera of the family. Plant Disease. 89:654-658. Zhang, S.C., G. Zhang, L. Yang, J. Chisholm, and H. Sanfaçon. 2005. Evidence that insertion of Tomato ringspot virus NTB-VPg protein in endoplasmic reticulum membranes is controlled by two domains: a C-terminal transmembrane helix and an N-terminal amphipathic helix. Journal of Virolology. 79:11766-11775. Book chapters and Reviews: Sanfacon, H., G. Zhang, J. Chisholm, B. Jafarpour, and J. Jovel. 2006. Molecular biology of Tomato ringspot nepovirus, a pathogen of ornamentals, small fruits and fruit trees. In Floriculture, Ornamental and Plant Biotechnology: Advances and Topical Issues (1st Edition). Teixeira da Silva, J. (Ed.). Global Science Books, London, UK. 3:540-546. Sanfaçon, H. 2005. Replication of positive-strand RNA viruses in plants: Contact points between plant and virus components. Canadian Journal of Botany. 83:1529-1549. Le Gall, O., T. Iwanami, A.V. Karasev, A.T. Jones, K. Lehto, H. Sanfaçon, J. Wellink, T. Wetzel, and N. Yoshikawa. 2005. Family Comoviridae. In Virus Taxonomy: The classification and nomenclature of viruses. The eighth report of the International Committee on Taxonomy of Viruses. 807-818. Le Gall, O., T. Iwanami, A.V. Karasev, A.T. Jones, K. Lehto, H. Sanfaçon, J. Wellink, T. Wetzel, and N. Yoshikawa. 2005. Family Sequiviridae. In Virus Taxonomy: The classification and nomenclature of viruses. The eighth report of the International Committee on Taxonomy of Viruses. 793-798. Le Gall, O., T. Iwanami, A.V. Karasev, A.T. Jones, K. Lehto, H. Sanfaçon, J. Wellink, T. Wetzel, and N. Yoshikawa. 2005. Genus Cheravirus. In Virus Taxonomy: The classification and nomenclature of viruses. The eight report of the International Committee on Taxonomy of Viruses. 803-805. Le Gall, O., T. Iwanami, A.V. Karasev, A.T. Jones, K. Lehto, H. Sanfaçon, J. Wellink, T. Wetzel, and N. Yoshikawa. 2005. Genus Sadwavirus. In Virus Taxonomy: The classification and nomenclature of viruses. The eighth report of the International Committee on Taxonomy of Viruses. 799-802.

Impact Statements

The Hawaiian pineapple industry has converted to newer hybrids which have lower incidences of mealybug wilt. Strategies that target control of virus and the mealybug vectors are being utilized to minimize the increase in virus incidence and work towards eradication. This is essential for sustaining the local Hawaii pineapple industry as well as the growing subsidiaries in foreign lands.
Resistant cultivars provide options for continued fruit production in areas that are impacted by Sharka, the disease caused by Plum pox virus. Resistant cultivars also serve as genetic resources for further variety development by incorporating them into breeding programs.
This result(that Tomato ringspot virus could not revert already established gene silencing)suggests that resistance to PPV in transgenic plum is robust and cannot be broken by infection by ToRSV, a virus known to occur in peaches and plums.
This result (that Hemagglutinin was identified as an important gene involved in the pathogenicity of Xylella fastidiosa) provides one of the first opportunities to initiate unconventional control strategies for the devastating diseases of peach and grape caused by these bacteria.