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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[07/26/2007] [10/22/2008] [09/11/2009] [11/19/2010] [07/25/2011]

Date of Annual Report: 07/26/2007

Report Information

Annual Meeting Dates: 05/30/2007 - 06/01/2007
Period the Report Covers: 01/01/2006 - 12/01/2006

Participants

Gabrielle Anderson, AC Diagnostics, Inc., ganderson@acdiainc.com;
Anne-Sophie Bellido, Special Crops, Canadian International Grains Institute, abellido@cigi.ca;
Lori Bittner, Agriculture & Agri-Food Canada, bittnerl@AGR.GC.CA;
Ralph Cavalieri (Administrative Advisor), Washington State University, cavalieri@wsu.edu;
Ken Eastwell, Washington State University, keastwell@wsu.edu;
Blake Ferguson, Canadian Food Inspection Agency, fergusonb@inspection.gc.ca;
Pam Fisher, OMAFRA Berry Crop Specialist, pam.fisher@ontario.ca;
Lauri Guerra, WA State Department of Ag., lguerra@prosser.wsu.edu;
John Halbrendt, Penn State Univ., jmh23@psu.edu;
John Hu, University of Hawaii, johnhu@hawaii.edu;
Delano James, Canadian Food Inspection Agency, jamesd@inspection.gc.ca;
Anna Kalinina, Agriculture & Agri-Food Canada, kalininaa@AGR.GC.CA;
Harold Larsen, Colorado State Univ., Harold.Larsen@Colostate.edu;
Chuck Lemmon, Canadian Food Inspection Agency, clemmon@inspection.gc.ca;
Daniele Liberti, Agriculture & Agri-Food Canada, libertid@AGR.GC.CA;
Tom Lowery, Agriculture & Agri-Food Canada, LoweryT@AGR.GC.CA;
Linda Malcolmson, Director of Special Crops, Oilseeds and Pulses, Canadian International Grains Institute, lmalcomson@cigi.ca;
Michelle McMullen, Ontario Soybean Growers, mmcmullen@soybean.on.ca;
Roberto Michelutti, Agriculture & Agri-Food Canada, micheluttir@agr.gc.ca;
Ray Mock, USDA-ARS-GRIN, rmock@ars-grin.gov;
Weston Msikita, PA Dept of Ag., wmsikita@state.pa.us;
Ramesh Pokharel, Colorado State University, rameshp@lamar.colostate.edu;
Michael Reimer, University of Manitoba, umreim26@cc.umanitoba.ca;
Adib Rowhani, Univ. of California, Davis, akrowhani@ucdavis.edu;
Annemiek Schilder, Michigan State University, schilder@msu.edu;
Susan Sibbald, Agriculture & Agri-Food Canada, sibbalds@AGR.GC.CA;
Dan Thompson, Canadian Food Inspection Agency, thompsonda@inspection.gc.ca;
Lining Tian, Agriculture & Agri-Food Canada, tianl@AGR.GC.CA;
Mike Tiffany, Agdia Inc., miket@agdia.com;
Yannis Tzanetakis, Oregon State Univ., tzanetai@science.oregonstate.edu;
T. Vickers, Agriculture & Agri-Food Canada, VickersT@AGR.GC.CA;
Huaiyu Wang, Agriculture & Agri-Food Canada, wanghy@AGR.GC.CA;
Di Wu, Agriculture & Agri-Food Canada, wud@AGR.GC.CA;
Daqun Yang, Agriculture & Agri-Food Canada, yangDa@AGR.GC.CA;

Brief Summary of Minutes

WERA-020: Virus and Virus-Like Diseases of Fruit Trees, Small Fruits, and Grapevines Committee - Annual Meeting May 29 to June 2, 2007 in Leamington, ON

Chair and Local Organizer: Roberto Michelutti, Canadian Clonal Genebank, Agriculture & Agri-Food Canada, Harrow ON; Secretary: Ken Eastwell, Washington State University, Prosser, WA

Meeting convened at 08:30 on May 30, 2007:

Chair Michelutti welcomed the participants to the meeting; Cavalieri (Administrative Advisor) reviewed the renewed structure of WERA's to bring research and extension personnel together.

Attendees represented the States and Provinces of British Columbia, California, Colorado, Hawaii, Manitoba, Michigan, Ontario, Oregon, Pennsylvania, and Washington

STATE/PROVINCE REPORTS:
Eastwell (WA - report attached on WERA-20 Homepage - Additional Documents section) reported on the development of a more robust assay Little cherry virus-1. There is growing concern that the milder symptoms caused by LChV-1 on current biological indicators may allow the virus to escape detection. On-going research on the cherry isolate of Cherry leafroll virus suggests that this virus can be transmitted to the fruit bearing tree by virus-infected pollen. Serological reagents are being developed to detect members of the genus Foveavirus that affect sweet cherry. Genetic analysis reveals a complex relationship between the members of this genus. The National Research Support Project-005 located at WSU-Prosser, continues to be the primary source of new virus tested fruit tree propagation material that serves both import and export of fruit tree propagation material.

Guerra (WA) indicated that Cherry leafroll virus had been detected in a certified seed block and increased monitoring is in place to minimize threats from this virus in the certification program. The tree fruit certification program is auditing the certification program to determine the status of Apple chlorotic leafspot virus and is finding some unexpected positives.

Halbrendt (PA - report attached on WERA-20 Homepage - Additional Documents section) reported on the status of the Plum pox virus eradication program initiated after the virus was confirmed in PA in 1999. The mandatory quarantines in large areas of the State have been rescinded since no plum pox virus has been detected in these areas for 3 years. Prunus species can now be replanted in these areas, although nursery activity is still prohibited. In 2006, six positive plants were identified and only one was in a commercial orchard. Trap plants and yellow traps continue to be analyzed for viruliferous aphids and possible unknown reservoirs of the virus.

Hu (HI - report attached on WERA-20 Hompage - Additional Documents section) indicated that a survey of citrus trees on the five major islands revealed an overall incidence of Citrus tristeza virus of 74%. Some infections could be detected with either serological or molecular assays, but not by both. Further analyses indicate that most trees are simultaneously infected with multiple strains of the virus. From this study, a strain that can be used as a cross protection agent was identified; field trials are in progress to evaluate this potential. Viruses associated with a citrus blight-like wilt disease in HI are under investigation to determine the nature and etiology of this disease. The long term goal is to develop a management strategy to allow the citrus industry to expand.

James (B.C.) has characterized Peach virus Agua (formerly identified as 4N6). This virus was identified through its reaction in ELISA with antiserum prepared to Plum pox virus. The virus also reacts in EM decoration assays with antiserum to Apple stem pitting virus. PcVA shares sequence and genome organization similar to ASPV, and share many peptide sequences in the C-terminus of the coat protein region. However, PcVA is a distinct member of genus Foveavirus in the Flexiviridae family.

Kalinina (ON - report attached on WERA-30 Homepage - Additional Documents section) examined the susceptibility of ornamental Prunus species to Plum pox virus. Generally, ELISA results of self-rooted plants were less definitive than those from tree grafted onto GF305. Inoculated P. americana, P. cistena, P. glandulosa, P. tomentosa developed distinct symptoms and the infection was confirmed by immunocapture RT-PCR, ELISA and by back inoculations. P. triloba yielded weak reactions whereas P. virginiana 'Schubert', P. serrulata 'Kwanzan' yielded inconsistent results that need further clarification. These are important potential host plants for PPV in North America.

Ferguson (ON) reported on the status of efforts in Canada to contain Plum pox virus. No PPV has been detected in two sites in Nova Scotia or three areas in Ontario for three years, so these areas are now removed from the quarantine area. However, the major quarantined area in Ontario remains. Results of the 2006 survey revealed 18 positives in the St. Catherines area. Eradication will only be possible with aggressive testing and enforcement. A group discussion followed regarding strategies that might be feasible to reduce the aphid transmission of PPV.

Larsen (CO - report attached on WERA-20 Homepage - Additional Documents section) established in-pot trials to determine the potential resistance of new rootstocks to transmission of Cherry raspleaf virus. Soil containing Bing trees on mazzard and 'Citation/Z-stem' rootstocks were infested with viruliferous nematodes in spring 2006. No symptoms are evident yet on the inoculated trees. Grape fanleaf virus was detected in a block of 'Cabernet franc' in 2006. The infection appeared to be localized although significant populations of dagger nematodes were detected. Studies will continue to determine if the CO populations of nematodes are vectors of GFLV.

Tiffany (Agdia) reported that a new ELISA test is available that recognizes all known strains of Plum pox virus.

Mock (USDA-NGRL-PDRU - report attached on WERA-20 Homepage - Additional Documents section) indicated that reorganization of the unit is complete and they are now working in close associated with USDA-APHIS to develop methods for the safe introduction of germplasm. A molecular assay has been reported to supplement the biological indicators currently used for the detection of Gooseberry vein banding virus. This will shorten time requirements for virus testing. A molecular assay for Cherry green ring mottle virus and Cherry necrotic rusty mottle was also developed. Some isolates of Cherry necrotic rusty mottle do not produce symptoms on the standard biological indicator 'Sam'. A RT-PCR assay for black currant reversion has been developed but validation is still required.

Lemmon (ON) indicated that audits of programs in France and Germany cause concern about phytoplasma diseases and led to the detection of phytoplasma (Bois noir) in a single shipment of vines imported into the Okanagan Valley. It is believed that grapevines are a dead end host for the phytoplasma, and that it moves into grapevines from weedy reservoirs. The known vector of the disease does not occur in B.C. Therefore, it is believed that removal of the two infected vines effectively eradicated the Bois noir. Future importations require hot water treatment to eliminate potential Bios noir infestations.

Results from Rowhani (CA - report attached on WERA-20 Homepage - Additional Documents section) indicate that Plum bark necrosis and stem pitting associated virus shares 97% with Apricot stem pitting virus in Italy, and has been found in cherry and plum. Sequence analysis indicates that this virus has a close relationship to Pineapple mealybug wilt associated virus and some of the grapevine leafroll associated viruses.

Msikita (PA - report attached on WERA-20 Homepage - Additional Documents section) is investigating the occurrence of Tomato ringspot virus in apple trees where it causes apple decline and eventual death. ELISA detection of ToRSV has been inconsistent and the more sensitive RT-PCR has revealed a much higher incidence of ToRSV. This underscores the need to re-examine current virus detection methods and the need for robust detection methods.

Anderson (AC Diagnostics) indicated that ELISA reagents are available for PVY-n and that AC Diagnostics will also perform contract research.

Schilder (MI) detailed the discovery of Plum pox virus in July 2006 at the South West Michigan Research and Extension Center. The infected 5-year old tree was an European plum on Pumiselect® rootstock and did not exhibit any symptoms. All Pumiselect trees in the NC-140 rootstock trial have been removed. Testing of all hosts within a 5 mile radius did not reveal any other infected trees. Based on these results, fruit production is allowed in the regulated area, but no nursery production within the 7 mile area. This included advanced selection of the breeding program and 58 elite selections were sent to NRSP-005 for virus testing and retention.

Nurseries in the MI blueberry certification programs are testing for shoestring, mottle, tobacco ringspot virus and tomato ringspot virus, and will include blueberry scorch.

Thompson (BC - report attached on WERA-20 Homepage - Additional Documents section) is evaluating the use of the 'TriFoCap' primers for the detection of tricho-, fovea-, and capilloviruses. These primers successfully detected 20 virus isolates from these genera and, with only one exception, detected them throughout the year. Cherry necrotic crook disease could only be detected in dormant wood. It was reported that of 247 Prunus samples, 3 false positive reactions were obtained from cherry, and from 181 pome fruit samples, 3 false positive were obtained. Therefore, caution in interpretation of results is necessary, the case for all PCR assays.

Tian (ON) is investigating the use of transgenic plants for resistance to Plum pox virus. The HC-Pro segment is an effective activator of post transcriptional gene silencing in Nicotiana benthamiana, and transformation of plum indicates that a high percentage of transformants are resistant to infection by the D strain of PPV. The advanced selections are sent to France for evaluation for resistance to other strains.

Tzanetakis (OR - report attached on WERA-20 Homepage - Additional Documents section) summarized the determination of the viruses associated with the rapid decline of strawberry in CA (predominantly Strawberry pallidosis virus). This disease situation was resolved through aggressive management techniques. Similar disease symptoms occur in B.C. but the aphid-borne Strawberry mild yellow edge virus is the underlying cause of decline. Laboratory tests for more than 20 viruses affecting strawberry have been developed to aid in the management of strawberry diseases. Raspberry bushy dwarf is re-emerging as an important disease in raspberry and more recently, in 'Marion' blackberry which develops severe fruit loss in response to infection. Transgenic plants of 'Meeker' red raspberry have been developed and preliminary testing showed that several lines offer robust field resistance. Blueberry scorch has become an important virus, particularly with the discovery that cranberry and huckleberry are latent hosts of the virus. Virus elimination programs are underway in OR. Status of several blackberry viruses was also described.

Michelutti (ON) expanded the indexing program of the Canadian Clonal Genebank collection of more than 3300 unique accessions. Indexing on 'Kwanzen' gave 14 positive reactions last year and 25 this year. In addition, 224 Prunus and 134 Fragaria were tested for nepoviruses. In parallel, 6 Fragaria were found to be infected with Strawberry mild yellow edge virus. Rubus accessions in the screenhouse (91) were tested for nepoviruses, Raspberry bushy dwarf virus and Tobacco streak virus. Three accessions were positive for RBDV and one was positive for TSV. Eighty-five Rubus accessions in the field were tested and 4 were infected with RBDV and 1 for TSV. Nineteen representatives of the 'Jesuit pears' have been transferred to the germplasm collection for genetic analysis at a later date. Last year, symptoms developed on Ribes similar to aphid damage or Gooseberry vein banding virus. Virus infection was confirmed by PCR, and a second virus was also detected. Tissue print blots in cooperation with Palles and Flores are being used to evaluate the viroid status of the collection.

Reports (attached on WERA-20 Homepage - Additonal Documents section) were submitted by WERA-020 participants unable to attend:
Deborah Golino, Ray Johnson, Simon Scott, and Aiming Wang.

Photographs attached to WERA-20 Homepage area.

Business meeting:

Cavalieri indicated that the project was revision was submitted in 2005 and authorized in 2006. The project will submit its next revision in 2010.

Eastwell gave a brief summary of the planning meeting of the National Clean Plant Network that was held in Greenbelt, MD on May 9-10. The successful creation and funding of the network would be an important step forward in controlling virus diseases of perennial fruit crops in the U.S. However, it will require several fundamental changes in the way industries and government agencies interact. WERA-020 participants may have a larger role in developing some of the guidelines for network operations.

Larsen offered to host the nest meeting of WERA-020 in Grand Junction, CO. Michelutti moved and Rowhani seconded to hold the meeting in Grand Junction during the middle two weeks of June 2008 - motion passed unanimously.

Larsen moved and Hu seconded that the WERA-020 meeting be held in MI in 2009 - motion passed unanimously.

Larsen moved and Eastwell seconded that WERA-020 participants formally extend appreciation for the efforts made by the hosts at Agriculture & Agri-Food Canada and the local organizer Roberto Michelutti for making the meeting both informative and enjoyable - motion passed unanimously.

Meeting adjourned.

Accomplishments

Plum bark necrosis and stem pitting associated virus causes severe necrosis of bark tissues, and necrotic pitting on the woody cylinders of Prunus salicina. PBNSPaV was alsdo identified in other Prunus species and cultivars: almond cv. 'Filippo Ceo', peach cvs. 'Springcrest' and 'May Crest', plum cv. 'Black Beaut', apricot cv. 'Castlebrite', and sweet cherry cv. 'Ferrovia'. The virus was detected in samples from Italy, Morocco, and Turkey. A robust molecular assay for Little cherry virus-1 from disperse geographic locations was developed and verified. Several ornamental Prunus species were identified as hosts for Plum pox virus. Plants on their own roots supported a lower virus titer and therefore may elude detection. Group specific primers for the detection of tricho-, fovea-, and capilloviruses were evaluated and found to be a reliable and valuable tool for rapid detection of any one of many viruses that affect temperate fruit trees. It was demonstrated that the rapid decline of strawberries in CA and BC was caused by two different viruses emphasizing the need to develop site-specific disease management tools.

Publications

Chisholm, J., G. Zhang, A. Wang, and H. Sanfacon. 2007. Peripheral association of a polyprotein precursor form of the RNA-dependent RNA polymerase of Tomato ringspot virus with the membrane-bound viral replication complex. Virology. (In Press) Eastwell, K.C., P.L. Sholberg, and R.J. Sayler. 2006. Characterizing potential bacterial biocontrol agents for suppression of Rhizobium vitis, causal agent of crown gall disease in grapevines. Crop Protection. 25:1191-1200. Gibson, P.G., G.L. Reighard, S.W. Scott, and D. Marini. 2006. Phenotypical Variation in Peach Trees Inoculated with Defined Mixtures of Viruses and Peach Latent Mosaic Viroid. Acta Horticulturae. Halgren, A.B., I.E. Tzanetakis, and R.R. Martin. 2007. Identification, characterization, and detection of Black raspberry necrosis virus. Phytopathology. 97:44-50. Jones, A.T., W.J. Mcgavin, V. Gepp, S.W. Scott, and M.T. Zimmerman. 2006. Purification and properties of Blackberry chlorotic ringspot, a new virus species in Subgroup 1 of the genus Ilarvirus found naturally infecting blackberry in the UK. Annals of Applied Biology. 149:125-135. Joyce, P.A., F.E. Constable, J. Crosslin, K. Eastwell, W.E. Howell, and B.C. Rodini. 2006. Characterisation of Pear blister canker viroid isolates from Australian pome fruit orchards. Australasian Plant Pathology. 35:465-471. Lima, M.F., R. Alkowni, J.K. Uyemoto, D. Golino, F. Osman, and A. Rowhani. 2006. Molecular analysis of a Californian strain of Grapevine rupestris stem pitting associated virus isolated from declining Syrah grapevines. Archive of Virology. 151:1889-1894. Liu, Z., R. Scorza, J-M Hily, S.W. Scott, and D. James. 2007. Engineering Resistance to Multiple Prunus Fruit Viruses Through Expression of Chimeric Hairpins. Journal of the American Society for Horticultural Science. 132:407-414. Martin, R.R. and I.E. Tzanetakis. 2006. Characterization, detection and management of strawberry viruses. Plant Disease. 90:384-396. Martin, R.R., I.E. Tzanetakis, M. Sweeney, and L. Wegener. 2006. A virus associated with blueberry fruit drop disease. Acta Horticulturae. 715:497-501. Melzer, M.J., W.B. Borth, F. Zee, M.E. Hilf, S.M. Garnsey, and J.S. Hu. 2006. Incidence and diversity of Citrus tristeza virus in the Hawaii. Phytopathology. 96:77. Melzer, M.J., W.B. Borth, F. Zee, M.E. Hilf, S.M. Garnsey, and J.S. Hu. 2006. Incidence, distribution, and diversity of Citrus tristeza virus in the Hawaiian islands. In: Proc. 16th Conf. IOCV. Pages 179-186. Osman, F., C. Leutenegger, D. Golino, and A. Rowhani. Real-time RT-PCR (TaqMan®) assays for the detection of grapevine leafroll associated virus 1, 2, 2-Redglobe strain, and 3. J. Virol. Methods. (In Press) Raghupathy, M.B., J.S. Griffiths, L.W. Stobbs, D.C.W. Brown, J.E. Brandle, and A. Wang. 2006. Transfection of Arabidopsis protoplast with a Plum pox virus (PPV) infectious clone for studying early molecular events associated with PPV infection. J. of Virological Methods. 136:147-153. Scott, S.W. and M.T. Zimmerman. 2006. The complete nucleotide sequence of the genome of Humulus japonicus latent virus. Archives of Virology. 151:1683-1687. DOI 10.1007/s00705-006-0771-6. Scott, S.W. and M.T. Zimmerman. 2006. Production of Full-length Copies of the Genomic RNAs of Prunus necrotic ring spot virus. Acta Horticulturae. Soule, M.J., K.C. Eastwell, and R.A. Naidu. 2006. First report of Grapevine leafroll-associated virus-3 in American Vitis grapevines in Washington State. Plant Disease. 90:1461. Susaimuthu, J., I.E. Tzanetakis, R.C. Gergerich, and R.R. Martin. 2006. Yellow vein-affected blackberries and the presence of a novel Crinivirus. Plant Pathology. 55:607-613. Tzanetakis, I.E., and R.R. Martin. 2007. Strawberry chlorotic fleck: Identification and characterization of a novel Closterovirus associated with the disease. Virus Research. 124:88-94. Tzanetakis, I.E., J.D. Postman, and R.R. Martin. 2007. First report of Blackberry chlorotic ringspot virus in Rubus sp. in the United States. Plant Disease. 91:463. Tzanetakis, I.E., A.B. Halgren, N. Mosier, and R.R. Martin. 2007. Identification and characterization of Raspberry mottle virus, a novel member of the Closteroviridae. Virus Research. 127:26-33. Tzanetakis, I.E., J.D. Postman, R.C. Gergerich, and R.R. Martin. 2006. A virus between families: nucleotide sequence and evolution of Strawberry latent ringspot virus. Virus Research. 121:199-204. Tzanetakis, I.E., J. Suisumathu, R.C. Gergerich, and R.R. Martin. 2006. Nucleotide sequence of blackberry yellow vein associated virus, a novel member of the Closteroviridae. Virus Research. 116:196-200. Tzanetakis, I.E., W.M. Wintermantel, A.A. Cortez, J.E. Barnes, S.M. Barrett, M.P. Bolda, and R.R. Martin. 2006. Epidemiology of Strawberry pallidosis associated virus and occurrence of pallidosis disease in North America. Plant Disease. 90:1343-1346. Wang, A., H. Sanfacon, L.W. Stobbs, D. James, D. Thompson, A.M. Svircev, and D.C.W. Brown. 2006. Plum pox virus in Canada: Progress in research and future prospects for diseases control. Canadian J. of Plant Pathology. 28:1-10. Wegener, L.A., R.R. Martin, M.G. Bernardy, L. Macdonald, and Z.K. Punja. 2007. Epidemiology and strain identification of Blueberry scorch virus on highbush blueberry in British Columbia. Canadian Journal of Plant Pathology. 28:250. Wegener, L.A., Z.K. Punja, and R.R. Martin. 2007. First report of Blueberry scorch virus in black huckleberry in British Columbia. Plant Disease. 91:328.

Impact Statements

The loss during the 2003-2004 season in California strawberry caused by Strawberry pallidosis associated virus (SPaV) was estimated to $25M. With identification of the pathogen and aggressive pest management the disease has almost been eliminated for the state.
The TriFoCap test was evaluated against a range of viruses mostly obtained from WERA-20 participants. The TriFoCap nested RT-PCR test is a useful tool for screening fruit tree samples for Tricho-, Fovea-, and Capilloviruses and can make the testing of quarantinable material more efficient and more rapid.
Quarantine regulations and the high cost of bringing in new stock from abroad make it critical for growers and researchers to be able to locate existing material already in the US. The National grape registry was created to provide a single comprehensive site listing all grape plant material available within the U.S. and to identify material that has been tested and certified as clean in regard to certain grapevine diseases.
Hawaii is capable of producing high quality citrus fruit that is often preferred over imported citrus whose quality has suffered from the long trip to the islands if it were not for the high incidence of Citrus tristeza virus. The development of citrus resistant to Hawaiian CTV strains would be beneficial to not only Hawaii, but also other citrus-producing regions in the US and abroad.
Results from PDRU research projects will benefit the USDA quarantine program by producing more effective pathogen detection methods, improving knowledge on etiology of poorly described pathogens, and the development of therapeutic methods to eliminate pathogens from potentially valuable germplasm. These improvements will help create a more effective quarantine program that encourages compliance with federal regulations regarding movement of germplasm and diminishes the temptations to smuggle plant material into the United States.

Date of Annual Report: 10/22/2008

Report Information

Annual Meeting Dates: 08/11/2008 - 08/13/2008
Period the Report Covers: 10/01/2007 - 09/01/2008

Participants

Guerra, Lauri (lguerra@prosser.wsu.edu) - WA State Dept. of Ag;
Halbrendt, John (jmh23@psu.edu) - Penn St. Univ.;
Hu, John (Johnhu@hawaii.edu) - Univ. of Hawaii;
Larsen, Harold (Harold.Larsen@colostate.edu) - Colo. St. Univ.;
Licha, Margarita (Margarita.F.Licha@aphis.usda.gov) - USDA-APHIS-, Beltsville;
Mock, Raymond (Raymond.Mock@ARS.USDA.GOV) - USDA-ARS, Beltsville;
Pokharel, Ramesh(Ramesh.Pokharel@Colostate.edu) - Colo. St. Univ.;
Vrient, Albert(avrient@agdia.com) - AgDia;

Brief Summary of Minutes

Minutes: H. Larsen, acting secretary.

The 2008 annual meeting of WERA-20 was held Aug. 11-13, 2008 at the Holiday Inn in Grand Junction, CO.

Participants:

Guerra, Lauri (lguerra@prosser.wsu.edu) - WA State Dept. of Ag

Halbrendt, John (jmh23@psu.edu) - Penn St. Univ.

Hu, John (Johnhu@hawaii.edu) - Univ. of Hawaii

Larsen, Harold (Harold.Larsen@colostate.edu) - Colo. St. Univ.

Licha, Margarita (Margarita.F.Licha@aphis.usda.gov) - USDA-APHIS-, Beltsville

Mock, Raymond (Raymond.Mock@ARS.USDA.GOV) - USDA-ARS, Beltsville

Pokharel, Ramesh (Ramesh.Pokharel@Colostate.edu) - Colo. St. Univ.

Vrient, Albert (avrient@agdia.com) - AgDia

The meeting opened at 9:00 am, Monday, Aug. 11 with a welcome by H. Larsen (local host). In the absence of the official chairman for the meeting, the group decided to have H. Larsen serve as the chairperson for the meeting. The projected secretary also was unable to attend, so H. Larsen agreed to record the meeting for the minutes and to prepare the minutes after the meeting conclusion.

State / Agency reports:

Pokharel (CO) - See written report: He reported on his work with dagger nematodes and Cherry Rasp Leaf Virus (CRLV), one of the primary virus disease problems facing cherry and apple growers in Colorado. Dagger nematodes are very common in soils within the area, but species identification in Xiphinema is difficult. Collaborative work to look at molecular identification of dagger species from Colorado Soils is underway with A. Szalanski (Univ. of Ark.). Pot-in-pot studies were established in 2006 to examine comparative susceptibility of Bing cherry on Citation / Z-interstem rootstock and on Mazzard rootstock to CRLV infection. No symptoms have been observed in any of the scions or rootstock suckers to date. Observations continue on Van and Bing cherry on Gisela 5 and Gisela 7 rootstocks for susceptibility / resistance to CRLV. Nicotiana benthamiana mechanically inoculated with CRLV using common buffer and carborundum powder in 2007 failed to show any symptoms. Apple and peach inoculated with diseased cherry as the tissue source have not produced any symptoms to date.

An incidence of Fanleaf virus on Cabernet franc grapes was found in fall 2006. No spread was detected via ELISA tests in adjacent vines nor in an adjacent block of Cabernet sauvignon, despite the presence of a substantial dagger nematode population in these soils. The block was removed in winter 2006-07, fumigated in late summer 2007, and replanted in 2008. It and the neighboring block are being monitored for any sign of spread.

A lively discussion of nematode associated viruses and vector nematode identification followed. Morphological variability of dagger nematodes found in Colorado soils is a great difficulty for identification. Halbrendt (PA) suggested establishing single female colonies for ID purposes (minimize morphological and genetic variability).

Hu (HI) - See written report. Pineapple mealybug wilt (PMW) research update: PMW has now been shown to be associated with four viruses (PMWaV-1, PMWaV-2, PMWaV-3, and PMWaV-4; all Ampeloviruses). Based on sequence available for PMWaV-4, it is distinctly different from the other three, PMWaV-1 toPMWaV-3. Badnavirus studies update: Cloning and sequencing of badnavirus-like particles in pineapple revealed the presence of four distinct clades. The phylogenetic relatedness of these clades to other badnaviruses, other Caulimoviridae members, and retro-like elements was examined. Grey pineapple mealybug had 100% transmission efficiency after a 3-day acquisition period and the PMWaV-2 virus persisted in these viruliferous mealybug vectors up to 3 days. Thus PMWaV-2 is transmitted by the grey pineapple mealybug in a semi-persistent manner. Longtailed mealybug also was shown to be a vector. Reverse transcription-polymerase chain reaction (RT-PCR) and PCR assays for PMWaV's and badnaviruses were used to determine the distribution and incidence of these viruses in two new commercially important pineapple hybrids and the germplasm accessions maintained at the ARS-USDA National Clonal Germplasm Repository in Hilo, HI. Differences were found within pineapple cultivars and hybrids with regard to incidence of PMWaV-2 and -3 and badnavirus clades A, C, & D. The high incidences of some PMWaVs and badnaviruses in newly-imported pineapple hybrids verify the importance of using virus screening assays to select virus-free plant material prior to mass propagation.

Halbrendt (PA) - See written report. Reported on the Plum Pox virus (PPV) situation. The PPV eradication project in PA seems to be working at this time. The regulated areas in PA have decreased from a high of 349 sq. miles in 2003 to 51 sq. miles in 2008. The 2007 survey produced negative results for the first time since the detection of PPV in 1999. Two small areas in Adams County and one in Cumberland County remain under regulation for PPV, but no positive or suspect samples were found in 2007. In New York, samples positive for PPV have been reported in Niagara County and suspects in Wayne County. A total of 26.7 acres of orchard were destroyed in 2007 because of the positive detections in 2006 and 2007. NY currently is using a 50-meter minimum removal buffer around any positive detection due to the close proximity of the infections to the Canadian PPV infected area and the uncertain risk of reinfection via the natural movement of aphids between the two areas. The PPV infection found in Michigan was on a Pumiselect rootstock from OR. One aspect of concern was that trees on Pumiselect rootstock were also sold to WalMart which will make tracking more difficult.

Guerra (WA) - See written report (from K. Eastwell, WA).
Washington Dept. of Agric. work: Recently encountered a problem with CLS virus in some WA nursery material; he is looking at possibility of field transmission. There is a need for better serological detection methods for cherry mottle leaf (peaches can serve as symptomless hosts), little cherry (becoming an increasingly frequent problem), and western-X disease (seems to be on the increase now). He also is looking at peach latent mosaic viroid and prune dwarf virus (PDV, specifically interactions with other Prunus viruses).

K. Eastwell's work: He has successfully produced monoclonal antibodies against Little cherry virus 1 (enhancing detection of this virus for quarantine / certification programs). Cherry leafroll virus (CLRV) is pollen-borne (successfully transmitted CLRV from pollen to the developing fruit), but controlled pollination of several thousand blossoms has not demonstrated transmission of the virus to the fruit-bearing tree; the virus gets as far as the sub-epidermal cell layer of the pedicel, but no further. Work on Foveaviruses in fruit trees and grapevines has focused on characterization, examination of molecular similarities, and development of polyclonal antibodies to the bacterial-expressed coat protein of a representative virus on one of the four distinct clades; this antibody reacts with all viruses within the same cluster. Another polyclonal antibody was developed for Rupestris stem pitting associated virus (RSPaV). Hop stunt viroid (HSVd) is of growing concern to hop producers; a hop root certification program has been revitalized to provide HSVd and virus-free roots to nurseries. The Washington Hop Commission has invested heavily in equipment and facilities for molecular detection of HSVd.

Main activities of NRSP-005 included: 1) rescuing the Mich. St. Univ. Peach breeding program after discovery of PPV at an MSU research station; 2) assisting USDA-APHIS-PPQ by providing therapy to virus-infected clones; & 3) distributing over 17,700 virus-tested buds to researchers & industry; & 4) virus testing and therapy of 185 new acquisitions of stone and pome fruit cultivars from nine foreign countries and eight U.S. states.

Creation of a National Clean Plant Network was mandated in the 2008 Farm Bill under "Te Food, Conservation, and Energy Act of 2008" and the legislation includes the establishment of clean plant centers for pathogen diagnosis and elimination. These will produce clean material for propagation and will maintain foundation blocks of pathogen-tested plant material throughout the USA. Organizational meetings have been held in Prosser, WA and Davis, CA to create a structural model for the network. The goal is to have the organization in place by Oct., 2008.

Licha (USDA-APHIS-PGQP) - On Oct. 1, 2005, APHIS assumed responsibility for the plant quarantine program in Beltsville, MD. Program Supervisor - Dr. Joe Foster; Team Leader - Dr. Margarita Licha (Fruit Plant Pathologist - Plant Germplasm Quarantine Program). She reviewed the policy for importing budwood and described the testing protocols used to detect pathogens for both pome and stone fruits and then provided a summary of program activities, goals, and needs for the future.

Mock (USDA-NGRL-PDRU) - See written report. The National Germplasm Resources Lab - Plant Disease Research Unit (NGRL-PDRU) performs research on viral and sub-viral pathogens of clonally propagated prohibited crop genera, emphasizing deciduous tree and small fruits, sugarcane, grasses, and sweet potoatoes. The mission of the unit is to characterize and investigate the etiology of poorly described diseases and pathogens of quarantine significance and to develop more reliable detection and elimination methods. Five current projects related to deciduous fruits include the following: 1) Development / adaptation of existing protocols for in vitro culture and therapy of infected stone and small fruits; 2) characterization of flowering cherry isolates of Cherry necrotic rusty mottle virus (CNRMV); 3) etiological investigations of several poorly characterized quarantine diseases of pome fruits (including flat limb/rubbery wood); 4) development of a detection method for six viroids that infect pome & stone fruits; and 5) etiological investigations of what is believed to be Stayman Blotch Virus in apple in the Shenandoah Valley, VA (w/ Dr. Keith Yoder, Va. Tech. Ag. Res. & Ext. Ctr., Winchester, VA). Results from PDRU research projects will benefit the USDA quarantine program by producing more effective pathogen detection methods, improving knowledge on etiology of poorly described pathogens, and developing therapeutic methods to eliminate pathogens from potentially valuable germplasm. An adjunct benefit is helping create a more effective quarantine program that encourages compliance with federal regulations regarding movement of germplasm and diminishes the temptations to smuggle plant material into the United States.

Cavalieri (WERA-20 Administrative Advisor) - Phone conference call, covered the following administrative items:

1) WERA-20 is approaching the time for the required Mid-Point Assessment of the committee. He will send electronic files of two forms to H. Larsen to forward to all members to fill out in April, 2009. Please give these your attention when you get them. He needs to submit a summary of each of these by June 1, 2009. Specifically, he needs each member to provide a one sentence "Impact Nugget" and a one sentence statement of "Who Cares & Why".

2) Update on the "Clean Plant Network" - a) National structures have been established for tree fruits and for grapes; & b) funding for NRSP-005 has been set for this year (to bridge to future funding arrangements).

3) The "Specialty Crops Research Initiative" - connections (multi-state) will be very important in successful submissions for these.

4) Avoid August for future meetings (participation this time is one reflection of problems for this timing). Face-to-Face meetings (annual) are NOT required for the committee - could be done via conference call if travel expenses should become prohibitive in the future. This might be a possibility for future years.

5) Hatch funds for next year - Few of the appropriation bills are likely to be passed until the next Congress (do have continuing resolution funding until such, at the same levels as prior budget). [Ray Mock (USDA-NGRL-PDRU) - funding under continuing resolutions until next spring on a month-by-month basis, 1/12 of budget each month.]

Vrient (AgDia) - Changes at AgDia are on the horizon. Mike Tiffany is contemplating retiring soon; fruit is being given increased importance in the restructuring as plant groups are being shuffled around. Albert Vrient is likely to assume stone fruit and ornamentals areas.

Experienced elevated PPV suspect detections (possibly elevated background levels) recently. Question to group as to possible causes: Halbrendt weeds have lots of natural materials within them that react to the system. [AgDia: used antisera from Canada: rabbit source]. Guerra possibly heatshock protein confounding results.

Possibilities for future? - Guerra - field detection strips for fruit (Immunostrip w/ dried reagent, immuno test using gold-labeled antibody; 30 min / test). Cost varies, GMO cheaper (viral/bacterial tests $2-5 each). Need for a good, simple tool for growers. TmRSV tests? - not currently available.

Business Meeting: Chaired by H. Larsen.

* Next years location (for 2009 meeting): MSP (Mock/Hu) - to accept invitation from Michigan St. Univ. to host the meeting.

* 2010 meeting location: MSP (Mock/Hu) - to go to Pennsylvania (WSU-Prosser as a backup).

* Date for 2009: MSP - Recommendation to look at May / June (virus symptoms better for field trips).

* Chairperson for 2009: MSP - to have local host or his/her designee serve as chairperson.

* Secretary for 2009: MSP - Leave to decide at the meeting.

New Business:

- L Guerra: There is a need for a manual of pome / stone fruit virus / virus-like diseases in order to capture info from people who are retiring. It needs to be peer reviewed and might best be in electronic media format. It is something to think about for next year. He will prepare a format suggestion to consider at the 2009 meeting.

Meeting was adjourned at 4:30 pm.

Field trips:

Tues: Field trip to Delta County orchards; return via the Grand Mesa scenic highway.

Wed: Field trip to Mesa County orchards (morning); tour of the Colorado National Monument (afternoon).

Reports submitted by WERA-20 members unable to attend 2008 meeting:

See Meeting Minutes Attachment section for full texts of individual reports.

Almeida (CA; UC-Berkeley)> - Transmission of grapevine leafroll-associated virus 3 by the vine mealybug: Grapevine leafroll disease is caused by grapevine leafroll-associated viruses (GLRaVs). Within this virus complex, GLRaV-3 is the predominant species in the world. Several GLRaVs have been shown to be transmitted from vine to vine by mealybugs although a detailed characterization of transmission biology is lacking. The introduction of the vine mealybug (Planococcus ficus) in California and other regions of the world may result in increasing disease incidence of established GLRaVs. We studied the characteristics of GLRaV-3 transmission by the vine mealybug. Our results indicate that the vine mealybug transmits GLRaV-3 in a semipersistent manner. First instars were more efficient vectors than adult mealybugs. GLRaV-3 transmission lacked a latent period in the vector. Virus transmission occurred with a 1-h acquisition access period (AAP) and peaked with a 24-h AAP. Mealybugs inoculated GLRaV-3 with a 1-h inoculation access period (IAP), and transmission efficiency increased with longer plant access period up to 24 h, after which transmission rate remained constant. After an AAP of 24 h, mealybugs lost GLRaV-3 and infectivity 4 days after virus acquisition. In addition, GLRaV-3 was not transovarially transmitted from infected females to their progeny as detected by reverse transcription polymerase chain reaction. In summary, we systematically analyzed transmission parameters of GLRaV-3 by the vine mealybug and showed that transmission of this virus occurs in a semipersistent manner. This research fills in important gaps in knowledge of leafroll virus transmission, which is critical for development of leafroll disease management practices.

Rowhani (CA; UC-Davis) - Real time TaqMan® RT-PCR (TaqMan® RT-PCR) assays were developed to detect the viruses associated with Rugose wood complex of grapevines. The viruses detected were Rupestris stem pitting-associated virus (RSPaV) in the genus Foveavirus, Grapevine virus A (GVA), Grapevine virus B (GVB) and Grapevine virus D (GVD) in the genus Vitivirus. The coat protein was found to be the most conserved gene within the viral species, therefore, the primers and probes for TaqMan® RT-PCR assays were designed from the multiple alignment of the coat protein sequence of various isolates of each virus. Comparisons were also made between the conventional one step RT-PCR and TaqMan® RT-PCR for the detection of these viruses using four fold serial dilutions of both purified RNA and crude extract prepared from grapevine tissue. Results showed that TaqMan® RT-PCR was more sensitive and could detect viruses at 32 and 256 fold higher dilutions for purified RNA and crude extract, respectively, compared to RT-PCR.

In a different experiment, Low Density Arrays (LDA) were designed based on the real-time RT-PCR (TaqMan®) assays for the specific detection of 13 viruses that infect Grapevines. The viruses included in the study were Grapevine leafroll associated viruses (GLRaV) types 1, 2, 3, 4, 5, and 9, Grapevine leafroll associated virus 2-Redglobe strain (GLRaV-2RG), RSPaV, GVA, GVB, Grapevine Fanleaf Virus (GFLV), Tomato Ringspot virus (ToRSV), and Grapevine Fleck virus (GFkV). The LDAs were evaluated against a wide range of geographically distributed isolates. Geographical locations included Africa, Europe, Australia, Asia, Latin America and the United States. High throughput detection of these viruses using LDAs was compared to RT-PCR and real time TaqMan® RT-PCR. The efficiency of different RNA extraction methodologies and buffers were compared for use in low density array detection. In addition improving the RNA extraction technique and testing the quality of the RNA using the 18S ribosomal RNA TaqMan® assay as an RNA specific internal control proved to generate better diagnostic assays. This is the first report on use of LDA for the detection of plant viruses.

Scott (SC) - Research on the bloom delay associated with the peach germplasm Ta Tao 5 and characterization of the virus and virus-like agents associated with this phenomenon has continued. Ta Tao 5 is infected with Peach latent mosaic viroid (PLMVd), Apple chlorotic leaf spot virus (ACLSV), and Asian prunus virus (APV). The complete nucleotide sequences of the isolate of PLMVd and ACLSV (GenBank Accession EU223295) have been determined. APV has been partially purified and approx 50% of the sequence of the virus has been determined.

Ta Tao 5 that had been heat-treated at NRSP-5, Prosser, WA has been shown to contain only APV according to repeated PCR tests. In 2008 trees of heat-treated T a Tao 5 exhibited no delay in bloom compared to other peach cultivars commonly grown in South Carolina. Trees of Ta Tao 5 bloomed at least 10 days after the heat-treated material.

A trial involving trees of the peach cultivar Springprince inoculated with different sources of ACLSV, PLMVd, and APV (heat-treated Ta Tao 5) and compared with trees that had been inoculated by transferring the mixture contained in Ta Tao 5 has been established. In 2008, only those treatments which contained PLMVd displayed bloom delay.

The APV infecting Ta Tao 5 appears to be a mixture of at least APV-1 and APV-3 (Marais et al., 2006. Virus Research 120: 176-183) and further research is needed to confirm this. A second trial involving the cultivar Juneprince and refined treatment mixtures based on the preliminary data from the trial with Springprince has been established and will be monitored for the next 5 -7 years.

See Meeting Minutes Attachment section for full texts of individual reports.

Minutes Attachment:

Attachment

Accomplishments

1. High incidences of some PMWaVs and badnaviruses were found in newly-imported pineapple hybrids; the discovery verifies the importance of using virus screening assays to select virus-free plant material prior to mass propagation. 2. Systematic analysis of transmission parameters for GLRaV-3 by the vine mealybug showed transmission of this virus occurs in a semipersistent manner. This research fills important knowledge gaps for leafroll virus transmission that are critical for development of leafroll disease management practices. 3. TaqMan® RT-PCR assays were found to be more sensitive and could detect viruses at 32 and 256 fold higher dilutions for purified RNA and crude extract, respectively, compared to RT-PCR, for viruses associated with Rugose wood complex of grapevines. The viruses detected were Rupestris stem pitting-associated virus (RSPaV) in the genus Foveavirus, Grapevine virus A (GVA), Grapevine virus B (GVB) and Grapevine virus D (GVD) in the genus Vitivirus. The enhanced efficiency of detection will help reduce risk of release of grape materials infected with these viruses to plant nurseries and thus lower incidence of such in plant materials purchased by grape growers.

Publications

Almeida, R.P.P. 2008. Ecology of emerging vector-borne plant diseases. pp. 70-77. In: Institute of Medicine Forum on Vector-borne diseases: Understanding the environmental, human health, and ecological connections. The National Academies Press, Washington, D.C. 350p. Almeida, R.P.P., Bennett, G.M., Anhalt, M.D., Tsai, C.W. and O'Grady, P. 2008. Spread of an introduced vector-borne banana virus in Hawaii. Molecular Ecology (accepted). Almeida, R.P.P., Nascimento, F.E., Chau, J., Prado, S.S., Tsai, C.W., Lopes, S.A. and Lopes, J.R.S. 2008. Genetic structure and biology of Xylella fastidiosa causing disease in citrus and coffee in Brazil. Applied and Environ. Microbiology 74:3690-3701. Anhalt, M.D. and Almeida, R.P.P. 2008. Effect of temperature, vector life stage and plant access period on transmission of Banana bunchy top virus to banana. Phytopathology 98:743-748. Chatterjee, S., Almeida, R.P.P. and Lindow, S.E. 2008. Living in two worlds: the plant and insect lifestyles of Xylella fastidiosa. Ann. Rev. of Phytopath. 46:243-271. Gibson , P.G. Reighard, G.L. Scott, S.W. , and Marini, D. 2008. Phenotypical Variation in Peach Trees Inoculated with Defined Mixtures of Viruses and Peach Latent Mosaic Viroid. Acta Horticulturae,781:541-546. Hooks, C.R.R., Wright, M.G., Kabasawa, D.S., Manandhar, R. and Almeida, R.P.P. 2008. Effect of Banana bunchy top virus infection on morphology and growth characteristics of banana. Ann. of Applied Biol. 153:1-9. Hu, J.S., D. M. Sether, M.J. Melzer, C. V. Subere, K. Cheah, Y. Chen, Qi Li, W. Borth, I. C. Wang, C. Nagai, and M.L. Wang. 2007. Characterization and Management of Pineapple Mealybug Wilt Associated Viruses. VI International Pineapple Symposium in Brazil. Hu, J.S., M.J. Melzer, D. M. Sether, C.V. Subere, W. Borth, and A.V. Karasev. 2008. The nucleotide sequence and genome organization of Pineapple mealybug wilt associated virus-1 and PMWaV-3 support a new genus in the family Closteroviridae. ASVAnnual Meeting at Cornell University. Jarugula, S., Soule, M.J., Rowhani, A. and Naidu, R.A. 2008. First report of Grapevine leafroll-associated virus-9 in Washington State vineyards. Plant Disease 92:485. Li, R. and Mock, R. 2008. Characterization of a flowering cherry strain of Cherry necrotic rusty mottle virus. Arch. Virology 153:973-978. Marini, D.B., Gibson, P.G. and Scott, S.W. 2008. The complete nucleotide sequence of an isolate of apple chlorotic leaf spot virus from peach (Prunus persica (L.) Batch). Arch. Virol. 153:1003-1005. Mekuria, T., Martin, R.R. and Naidu, R. A. 2008. First report of the occurrence of Grapevine fanleaf virus in Washington State vineyards. Plant Disease 92:1250. Melzer, M.J., Sether, D.M., Karasev, A.V. and Hu, J.S. 2008. Complete nucleotide sequence and genome organization of Pineapple mealybug wilt-associated virus-1. Arch. Virology. 153:707-714. Prado S.S. and Almeida, R.P.P. 2008. Phylogenetic placement of pentatomid stink bug gut symbionts. Current Microbiology. (in press) Prado, S.S., Lopes, J.R.S., Demetrio, C.G.B., Borgatto, A.F. and Almeida, R.P.P. 2008. Host colonization differences between citrus and coffee isolates of Xylella fastidiosa in reciprocal inoculation. Scientia Agricola 65:251-258. Sether, D.M., Melzer, M.J., Subere, C.V.Q., Borth, W.B., and Hu, J.S. 2008. Genome organization, phylogenetic relationships, and distribution of Pineapple mealybug wilt associated virus-3 in Hawaii. Virus Genes. (Manuscript submitted) Subere, C.V.Q., Sether, D.M., Zee, F. and Hu, J.S. 2007. Diversity and distribution of pineapple mealybug wilt-associated viruses (PMWaVs) and pineapple badnaviruses in Hawaii. American Phytopathological Society Meeting. Phytopathology 97:S112. Tsai, C.W., Chau, J., Fernandez, L., Bosco, D., Daane, K.M., and Almeida, R.P.P. 2008. Transmission of Grapevine leafroll-associated virus 3 by the vine mealybug (Planococcus ficus). Phytopathology 98:1093-1098.

Impact Statements

Regulatory agencies often have difficulty accessing current and accurate scientific information and advice. The WERA-20 provided a forum for accessing this information, which is often unpublished, for use in formulating regulations and making decisions which have a major effect on the fruit industry.
Eradication efforts for Plum Pox Virus in Pennsylvania have greatly reduced the area of incidence from 2004 to 2008. Continued vigilance and lack of positive samples for 3 years will allow producers to replant stone fruit trees and return to production. This demonstrates the value of concerted effort to eradicate such diseases.

Date of Annual Report: 09/11/2009

Report Information

Annual Meeting Dates: 06/14/2009 - 06/17/2009
Period the Report Covers: 10/01/2008 - 09/01/2009

Participants

Ralph Cavalieri, administrative advisor, Washington State University, Pullman, Washington;
John Hu, University of Hawaii, Honolulu, Hawaii;
David Johnson, Missouri Department of Agriculture, Jefferson City, Missouri;
Richard Kaitany, Michigan Department of Agriculture, East Lansing, Michigan;
Alexander Karasev, University of Idaho, Moscow, Idaho;
Ruhui Li, USDA-ARS, Beltsville, Maryland;
Margarita Licha, USDA-APHIS, Beltsville, Maryland;
Roberto Michelutti, Agriculture and Agri-Food Canada, Leamington, Ontario, Canada;
Timothy Miles, Michigan State University (graduate student), Michigan;
Raymond Mock, USDA-ARS, Beltsville, Maryland;
Sudharshana Mysore, USDA-ARS Davis, California;
Ramesh Pokhari, University of Colorado, Grand Junction, Colorado;
Joseph Postman, USDA-ARS, Corvallis, Oregon;
Kenneth Rauscher, Michigan Department of Agriculture, East Lansing, Michigan;
Diane Rytlewski-Brown, Michigan State University Extension, Benton Harbor, Michigan;
Annemiek Schilder, Michigan State University, East Lansing, Michigan;
Simon Scott, Clemson University, Clemson, South Carolina;
Yannis Tzanetakis, University of Arkansas, Fayetteville, Arkansas;
Albert Vrient, Agdia Inc., Elkhart, Indiana;

Brief Summary of Minutes

Meeting Program:

Chair, Local Organizer and Secretary: Annemiek Schilder, Michigan State University, East Lansing, Michigan.

Sunday June 14: arrival, 8-10 pm: Welcome reception.

Monday June 15 (8:30 am-5:30 pm): State reports by participants. See the attached full reports under the link for the Meeting Minutes. A special presentation on the National Clean Plant Network was made by Joseph Postman.

Attendees visited the MSU Southwest Michigan Research and Extension Center to view virus symptoms in grape vineyards, and cherry and apple orchards. A presentation was made detailing the response to discovery of Plum pox virus in the MSU breeding program and the operations to rescue advanced peach selections. Nurseries were toured to observed tissue culture practices to produce blueberry plants; symptoms of several viruses were also observed in neighboring blueberry plantings.

Tuesday June 16: (9 am-5 pm): MSU Southwest Michigan Research and Extension Center (SWMREC, Benton Harbor, Michigan)

Welcome by Dr. Tom Zabadal, Station Director and presentation on virus symptoms in grapes
Presentation by Michael Hansen (MDA) and Dr. Bill Shane (MSU Extension) on Plumpox virus find at SWMREC and eradication program and rescue of peach breeding materials
Tour of cherry planting (prunus necrotic ringspot, prune dwarf virus); apple orchard (apple mosaic), and vineyard (tobacco ringspot virus) at SWMREC
DeGrandchamps nursery: visit nursery an learn about steps in propagation from tissue culture and virus testing program, blueberry fields with blueberry mosaic and tobacco ringspot symptoms
Visit to Trevor Nichols Research Complex in Fennville, MI, to view blueberry shock virus in blueberry planting.
Wine tour and dinner at Fenn Valley Vineyard in Fennville, Michigan; view vineyard with decline due to Roesleria subterranea root rot.
Business meeting;

1. The future role of NRSP-5 in providing foundation material to the National Clean Plant Network was discussed. NRSP-5 will no longer exist after Sept 30, 2009 but Washington State (WSU)- Ken Eastwell will operate under another name and continue as previously. Two extensive lists of graft-transmissible conditions that affect stone and pome fruits have been assembled by the Fruit tree clean plant netowrk. They present a considerable dilemma when considering which graft transmissible agents should be tested for by WSU and other programs prior to releasing foundation material to the NCPN and distribution from state certification programs. The two lists have already been "culled" somewhat as many of the names on them derive from single reports of a graft transmissible disease in the 1930 and 1940s. However, the lists are still unmanageable (unlike the corresponding lists for grapevines). In many instances authenticated cultures of the disease and agent no longer exist. The suggestion was made that if an authenticated culture does not exist, the name should be removed from the list. To this end, it was proposed to circulate the two lists to members of WERA-20 requesting that they identify any cultures of the diseases and agent that they possess. The responses will be collated and reduced (hopefully) lists will be circulated for further comment and final approval. Simon Scott will circulate the lists using the mailing list used by Annemiek Schielder to establish the meeting in Michigan. This proposal was accepted by the meeting and given unanimous support.

2. Competitive funding in current climate;

3. A potential fruit virologist position at MSU was discussed

4. Decided on location of next meeting in Idaho in September 2010. Alexander Karasev will be our host.

Meeting Adjourned

Wednesday June 17: 8:30 am-5 pm:
- Field trip to Agdia, Inc.,in Elkhart, Indiana; toured diagnostic and research facilities
- Hill Top Nursery, Hartford, Michigan: visited propagation blocks, mother blocks, storage facility, on-site virus-testing laboratory, greenhouse with graft-indexed plants for virus testing.
Minutes Attachment:
Attachment

Accomplishments
A consortium between Arkansas, the Carolinas, Mississippi and Oregon was formed through WERA-020 to study yellow vein disease (YVD) that has been one of the major problems for blackberry production in the Southeast United States for the last 7-9 years. More than 10 viruses in plants showing typical disease symptoms were identified. Symptoms are similar across states but virus species differ, with Blackberry yellow vein associated virus and Blackberry virus Y being the most common viruses in Arkansas whereas in the Carolinas Blackberry yellow vein associated virus, Blackberry chlorotic ringspot virus and Tobacco ringspot virus are more common. This is the 10th year of the PPV eradication effort in Pennsylvania since the detection of PPV in an orchard in Adams County in the fall of 1999. These surveys are a cooperative effort between APHIS PPQ, PDA, and Penn State University with each supplying infrastructure, equipment, and personnel. The regulated areas during that time have decreased from a high of 349 square miles in 2003 to 48 square miles in 2009. The 2007 survey produced negative results for the first time since the detection of PPV in 1999. The negative survey status continued in 2008 increasing the anticipation of being able to declare eradication in Pennsylvania at the end of the 2009 survey. In the interim, two small areas in Adams County and one small area in Cumberland County remain under regulation for PPV. A limited survey of Idaho vineyards was conducted by WERA-020 participants from WA, ID, and OR (Rayapati, Karasev & Martin). The results indicated widespread occurrence of GLRaV-3 in several wine grape cultivars. 
Publications
Almeida, R.P.P. 2008. Ecology of emerging vector-borne plant diseases. p70-77. In: Instititute of Medicine Forum on Vector-borne diseases: Understanding the environmental, human health, and ecological connections. The National Academies Press, Washington, D.C. 350p. Almeida, R.P.P., Bennett, G.M., Anhalt, M.D., Tsai, C.W. and O'Grady, P. 2009. Spread of an introduced vector-borne banana virus in Hawaii. Molecular Ecology 18:136-146. Almeida, R.P.P., Nascimento, F.E., Chau, J., Prado, S.S., Tsai, C.W., Lopes, S.A. and Lopes, J.R.S. 2008. Genetic structure and biology of Xylella fastidiosa causing disease in citrus and coffee in Brazil. Applied and Environmental Microbiology 74:3690-3701. Anhalt, M.D. and Almeida, R.P.P. 2008. Effect of temperature, vector life stage and plant access period on transmission of Banana bunchy top virus to banana. Phytopathology 98:743-748. Chatterjee, S., Almeida, R.P.P. and Lindow, S.E. 2008. Living in two worlds: the plant and insect lifestyles of Xylella fastidiosa. Annual Review of Phytopathology 46:243-271. Daugherty, M.P. and Almeida, R.P.P. 2009. Estimating Xylella fastidiosa transmission parameters: decoupling sharpshooter number and feeding period. Entomologia Experimentalis et Applicata 132:84-92. Daugherty, M.P., Bosco, D. and Almeida, R.P.P. 2009. Temperature mediates vector transmission efficiency: inoculum supply and plant infection dynamics. Annals of Applied Biology in press. Eastwell KC, du Toit LJ, Druffel KL. 2009. Helleborus net necrosis virus: A new Carlavirus associated with black death of Helleborus spp. Plant Disease. 93:332-338. Eastwell KC, Glass JR, Druffel KL. 2008. First report of infection of poison hemlock and celery by Apium virus Y in Washington State. Plant Disease. 92:1710. Golino, D.A. and Almeida, R.P.P. 2008. Studies needed of vectors spreading leafroll disease in California vineyards. California Agriculture 62: 174. Hooks, C.R.R., Fukuda, S., Perez, E.A., Manandhar, R., Wang, K.H., Wright, M.G. and Almeida, R.P.P. 2009. Aphid transmission of Banana bunchy top virus to banana after treatment with a bananacide. Journal of Economic Entomology 102: 493-499. Hooks, C.R.R., Manandhar, R., Perez, E.A., Wang, K.H. and Almeida, R.P.P. 2009. Comparative susceptibility of two banana cultivars to Banana bunchy top virus under laboratory and field environments. Journal of Economic Entomology 102: 897-904. Hooks, C.R.R., Wright, M.G., Kabasawa, D.S., Manandhar, R. and Almeida, R.P.P. 2008. Effect of Banana bunchy top virus infection on morphology and growth characteristics of banana. Annals of Applied Biology 153:1-9. Isaacs, R., Schilder, A., Miles, T., and Longstroth, M. 2008. Blueberry Aphid and Blueberry Shoestring Virus. Michigan Blueberry Facts. Michigan State University Extension Bulletin E-3050. Isaacs, R., Schilder, A., Zabadal, T., and Weigle. T. 2007. A pocket guide for grape IPM scouting in the North Central and Eastern U.S. Michigan State University Extension Bulletin E-2889. 3rd Edition. Isaacs, R., Schilder, A., Zabadal, T., and Weigle. T. 2008. Guía de Bolsillo para la Inspección de la Vid bajo Manejo Integrado de Plagas en el Centro Norte y el Este de los EEUU. Michigan State University Extension Bulletin E-2889SP. Kiliny, N. and Almeida, R.P.P. 2009. Xylella fastidiosa afimbrial adhesins mediate cell transmission to plants by leafhopper vectors. Applied and Environmental Microbiology 75:521-528. Lopes, J.R.S., Daugherty, M.P. and Almeida, R.P.P. 2009. Context-dependent transmission of a generalist plant pathogen: host species and pathogen strain mediate insect vector competence. Entomologia Experimentalis et Applicata 131: 216-224. Prado, S.S. and Almeida, R.P.P. 2009. Phylogenetic placement of pentatomid stink bug gut symbionts. Current Microbiology 58:64-69. Prado, S.S. and Almeida, R.P.P. 2009. Role of symbiotic gut bacteria in the development of Acrosternum hilare and Murgantia histrionica (Hemiptera, Pentatomidae). Entomologia Experimentalis et Applicata 132:21-29. Prado, S.S., Golden, M., Follett, P.A., Daugherty, M.P. and Almeida, R.P.P. 2009. Demography of gut symbiotic and aposymbiotic Nezara viridula (L.) (Hemiptera, Pentatomidae). Environmental Entomology 38:103-109 . Prado, S.S., Lopes, J.R.S., Demetrio, C.G.B., Borgatto, A.F. and Almeida, R.P.P. 2008. Host colonization differences between citrus and coffee isolates of Xylella fastidiosa in reciprocal inoculation. Scientia Agricola 65:251-258. Schilder, A. C., and Miles, T. D. 2008. Virus and Viruslike Diseases of Blueberries. Michigan Blueberry Facts. Michigan State University Extension Bulletin E-3048. Schilder, A. M. C., Isaacs, R., Hanson, E., Cline, B. 2008. A Pocket Guide to IPM Scouting in Highbush Blueberries, 2nd edition. Michigan State University Extension Bulletin E-2928. Schilder, A. M. C., Isaacs, R., Hanson, E., Cline, B., Wise, J., Garcia Salazar, C., and France, A. 2008. Guía de Bolsillo para la Inspección de Plagas en Arandanos Highbush bajo Manejo Integrado de Plagas. Michigan State University Extension Bulletin E-2928SP. Schilder, A., Wharton, P., Cline, W., Isaacs, R., Hanson, E., Longstroth, M., Svoboda, D., Thompson, R., Landis, J., and Duynslager, L. 2005 (updated 2009). MSU blueberry website (www.blueberries.msu.edu). Tsai, C.W., Chau, J., Fernandez, L., Bosco, D., Daane, K.M., and Almeida, R.P.P. 2008. Transmission of Grapevine leafroll-associated virus 3 by the vine mealybug (Planococcus ficus). Phytopathology 98:1093-1098. 
Impact Statements
1. Studies initiated through WERA-020 associations led to the development of a Specialty Crops Research Initiative grant to study the virus epidemiology and prepare a scheme that will eliminate or minimize the impact of disease in black berry production.
2. Three consecutive years of negative Plum pox virus survey results in Pennsylvania are required to rescind the remaining quarantines that prohibit growers from resuming establishment of Prunus orchards. A negative result in 2009 will be the third and rebuilding of the temperate fruit tree industry could then be initiated to restore the previously $26.2M/year stone fruit industry. The nursery propagation quarantine will remain effect for an additional 3 years after formerly infected areas are released from regulation.
3. This finding of grapevine leafroll disease agents in the Idaho wine grape growing region is leading to changes in grapevine growing practices in Idaho, which include amendments to state regulations of grape budwood movements, implementation of control measures against mealybugs, and development of monitoring of virus incidence and spread.
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Date of Annual Report: 11/19/2010

Report Information

Annual Meeting Dates: 09/20/2010 - 09/22/2010
Period the Report Covers: 10/01/2009 - 09/01/2010

Participants

Cavalieri, Ralph, Washington State University, email: cavalieri@wsu.edu;
Clayton, Lydia, University of Idaho Extension, email: lclayton@uidaho.edu;
Eastwell, Ken, Washington State University, email: keastwell@wsu.edu;
Guerra, Lauri, WA State Dept of Agriculture, email: lguerra@prosser.wsu.edu;
Hu, John, University of Hawaii, email: johnhu@hawaii.edu;
Karasev, Alexander, University of Idaho, email: akarasev@uidaho.edu;
Li, Ruhui, USDA-ARS, National Germplasm Resources, Beltsville, MD,
email: ruhui.li@ars.usda.gov;
Licha, Margarita, USDA-APHIS-PPQ-PHP, Beltsville, MD,
email: Margarita.F.Licha@aphis.usda.gov;
Martin, Robert, USDA-ARS, Corvallis, OR, email: martinrr@science.oregonstate.edu;
Masters, Carol, Canadian Food Inspection Agency, Sidney, B.C.,
email: Carol.Masters@inspection.gc.ca;
Mock, Ray, USDA-ARS-PDRU, email: Raymond.Mock@ARS.USDA.GOV;
Nakhla, Mark, USDA-APHIS, Beltsville, MD, email: Mark.K.Nakhla@aphis.usda.gov;
Pokharel, Ramesh, Colorado State University, email: rameshp@lamar.colostate.edu;
Postman, Joseph, USDA-ARS, Corvallis, OR, email: Joseph.Postman@ars.usda.gov;
Rayapati, Naidu, Washington State University, email: naidu@wsu.edu;
Reddout, Terri, NCPN-Fruit Trees & Hops, email: terri.reddout@wsu.edu;
Rowhani, Adib, University of California-Davis, email: akrowhani@ucdavis.edu;
Sabanadzovic, Sead, Mississippi State University,
email: ssabanadzovic@entomology.msstate.edu;
Schilder, Annemiek, Michigan State University, email: schilder@msu.edu;
Scott, Simon, Clemson University, email: sscott@clemson.edu;
Sutula, Chet, Agdia, Inc., email: chet@agdia.com;
Vavricka, Liz, Idaho Department of Agriculture, email: Liz.Vavricka@agri.idaho.gov;
Vidalakis, Georgios, UC-Riverside, email: georgios.vidalakis@ucr.edu

Brief Summary of Minutes

The annual meeting was held September 20 to September 22, 2010 at The Grove Hotel in Boise, Idaho and hosted by local chair and organizer, Alexander Karasev, University of Idaho, Moscow, Idaho.

To view the full minutes and the state reports, click on the link below for the minutes attachment.

The meeting convened at 09:00 on September 20, 2010:

Karasev (local Chair) and Cavalieri (Administrative Advisor) provided welcoming remarks. Moya Shatz, Executive Director, Idaho Wine Commission introduced the Idaho wine industry and its increasing impact to the states economy.
Individual state/province reports were presented from California, Washington, Oregon, Idaho, Michigan, Hawaii, British Columbia, California (citrus), South Carolina, Mississippi and Colorado. Reports were also presented from USDA-APHIS-PPQ and USDA-ARS scientists in Beltsville, MD.

Business meeting:

Cavalieri indicated WERA-20 must submit a project revision for renewal to ARC by January 15, 2011. Ken Eastwell and Naidu Rayapati volunteered to coordinate the revision. Reports and publication lists since 2007 must be sent to Eastwell by December 15, 2010.

Chair Karasev suggested the next WERA-20 meeting be held at Oregon State University in Corvallis. The group unanimously agreed. Robert Martin and Joseph Postman agreed to be co-chairs of the meeting and will decide on dates. It was also decided to hold the following meeting in the southeast in or before May, 2012; Simon Scott at Clemson University will explore the possibility.

A discussion of the National Clean Plant Network followed. Postman provided a summary of past funding and current status of NCPN funding. As of September 2010, networks for fruit trees, grapevines, hops, berries and citrus have been created and funded. Networks for figs, olive, potatoes and sweet potatoes are being considered. The Tier 2 specialty crop boards from berries, citrus, hops, grapevines and fruit trees were represented at the meeting and discussed some of the challenges of the future funding were discussed.

WERA-020 is regarded as an important group with closely allied interests to provide information and a focal point for developing much of the data required for NCPN operations. Examples are the assistance in locating voucher samples of many diseases in disease collections and in identifying pathogens of regional concern for consideration by the NCPN. Parallel missions of WERA-020 and the NCPN should lead to closer association.

Formal meeting adjourned. Field tours of facilities in southern Idaho were conducted on September 21 and September 22.

To view the full minutes and the state reports, click on the link below.

Minutes Attachment:

Attachment

Accomplishments

1. Collaborations built through WERA-20 led to the development and funding of a Specialty Crops Research Initiative grant to study the epidemiology of the viruses involved in yellow vein disease, crumbly fruit and decline of blackberry. The grant involves institutions from Arkansas, Oregon, North Carolina, California and Mississippi. A new virus genus was discovered and it was found throughout the Southeast in both wild and cultivated blackberries. 2. A collaborative project involving USDA-ARS, New York, Pennsylvania and Washington resulted in the development of a more reliable and practical molecular assay for tomato ringspot virus, a serious virus of fruit trees and grapevines in many production areas of the U.S. 3. Information exchange between institutions has improved the availability of germplasm for fruit tree breeding programs and commercial cultivars for production. This is the direct result of improved testing methods and operations management. The USDA-APHIS-PPQ facility in Maryland released 269 accessions from foreign sources in 2010, up from just 39 in 2007. The university program in Washington acquired 100 new accessions in 2010, 28% of which were virus infected. These included material from USDA breeding programs (28), from foreign sources (47) and proprietary clones from domestic sponsors (23). In addition to acquiring new accessions, 5,773 virus-tested buds were distributed from the Washington site to nurseries, growers, researchers and quarantine programs.

Publications

Al Rwahnih M, Daubert S, Golino D, Rowhani A. 2009. Deep sequencing analysis of RNAs from a grapevine showing Syrah decline symptoms reveals a multiple virus infection that includes a novel virus. Virology 387, 395-401. Alabi OJ, Martin RR, Naidu RA. 2010. Sequence diversity, population genetics and potential recombination events in Grapevine rupestris stem pitting-associated virus in Pacific Northwest Vineyards. Journal of General Virology 91:265-276. Crosslin JM, Eastwell KC, Davitt CM, Abad JA. 2010. First report of seedborne Cherry leaf roll virus in wild potato, Solanum acaule, from South America. Plant Disease 94:782-783. Eastwell KC, Howell WE. 2010. Characterization of Cherry leaf roll virus in sweet cherry in Washington State. Plant Disease 94:1067. Gutha LR, Casassa LF, Harbertson JF, Naidu RA. 2010. Modulation of flavonoid biosynthetic pathway genes and anthocyanins due to virus infection in grapevine (Vitis vinifera L.) leaves. BMC Plant Biology 2010, 10:187 Hajeri S, Ramadugu C, Keremane M, Vidalakis G, Lee R. 2010. Nucleotide Sequence and Genome Organization of Dweet mottle virus and Its Relationship to Members of the Family Betaflexiviridae. Archives of Virology. 155, 1523-1527. Jarugula S, Alabi OJ, Martin RR, Naidu RA. 2010. Genetic variability of natural populations of Grapevine leafroll-associated virus-2 in Pacific Northwest vineyards. Phytopathology 100:698-707. Jarugula S, Gowda S, Dawson WO, Naidu RA. 2010. 3'-coterminal subgenomic RNAs and putative cis-acting elements of Grapevine leafroll-associated virus 3 reveals 'unique' features of gene expression strategy in the genus Ampelovirus. Virology Journal 2010. 7:180. Martin RR, Zhou J, TzanetakisIE. 2010. Blueberry latent virus: An amalgam of the Partitiviridae and the Totiviridae. Virus Research, doi:10.1016/j.virusres.2010.09.020 Mekuria TA, Naidu RA. 2010. First report of grapevine virus sequences highly similar to Grapevine Syrah virus-1 from Washington vineyards Plant Disease, 94: 787. Naidu RA, Mekuria TA. 2010. First report of Grapevine fleck virus from Washington vineyards. Plant Disease 94:84. Riga E, Larsen R, Eastwell KC, Guerra N, Guerra L, Crosslin JM. 2009. Rapid detection of Tobacco rattle tobravirus in viruliferous Paratrichodorus allius from greenhouse and field specimens. Journal of Nematology 41:60-63. Tzanetakis IE, Guzmán-Baeny TL, VanEsbroeck ZP, Fernandez GE, Martin RR. 2009. First report of Impatiens necrotic spot virus in blackberry Southeastern United States. Plant Disease 93:432. Tzanetakis IE, Laney AG, Keller KE, Martin RR. 2010. New viruses found in fig exhibiting mosaic symptoms. Julius-Kühn-Archiv 427:79-82. Tzanetakis IE, Martin RR, Scott SW. 2010. .Genomic sequences of blackberry chlorotic ringspot virus and strawberry necrotic shock virus and the phylogeny of viruses in subgroup 1 of the genus Ilarvirus. Archives of Virology 155:557-561. Vidalakis G, Pagliaccia D, Bash JA, Semancik JS. 2010. Effects of mixtures of citrus viroids as Transmissible small nuclear RNA (TsnRNA) on tree dwarfing and commercial scion performance on Carrizo citrange rootstock. Annals of Applied Biology.157, 415-423.

Impact Statements

The perennial specialty crops served by the WERA-020 represent a significant total of U.S. agriculture with a farm gate value of $18 billion (NASS, 2008). Clean plant programs facilitated the release of 316 accessions from foreign sources in 2010, providing access to valuable material for nurseries and growers, and for crop improvement.
WERA-020 effectively fostered collaborations that led to significant advancements in virus disease management. A new virus was found to be the most widespread pathogen of blackberries and, with data gained by a team of scientists, control methods are being implemented. Similarly, past successes in discerning biological parameters of blueberry diseases has resulted in effective control programs in several states including Michigan, Washington and Oregon.

Date of Annual Report: 07/25/2011

Report Information

Annual Meeting Dates: 07/12/2011 - 07/14/2011
Period the Report Covers: 10/01/2010 - 09/01/2011

Participants

Cavalieri, Ralph (cavalieri@wsu.edu) - Washington State University;
Clayton, Lydia (lclayton@uidaho.edu) - University of Idaho;
Coneva, Elina (edc0001@auburn.edu) - Auburn University;
Eastwell, Ken (keastwell@wsu.edu) - Washington State University;
Edmunds, Brooke (bedmunds@oda.state.od.us - Oregon Dept. of AG;
Guerra, Lauri (lguerra@agr.wa.gov) - WSDA;
Hu, John (johnhu@hawaii.edu) - University of Hawaii;
Karasev, Alex (akarasev@uidaho.edu) - University of Idaho;
Li, Ruhui (Ruhui.Li@ars.usda.gov) - USDA-ARS;
Licha, Margarita (Margarita.F.Licha@aphis.usda.gov) - USDA-APHIS-PPQ;
Martin, Robert (bobmartin@ars.usda.gov) - USDA-ARS Hort. Crops Lab;
Masters, Carol (Carol.Masters@inspection.gc.ca) - Canadian Food Inspections Agency, Sidney;
Pokarel, Ramesh (ramesh@colostate.edu) - Colorado State University;
Postman, Joseph (Joseph.Postman@ars.usda.gov) - USDA-ARS;
Rudyj, Erich (Erich.S.Rudyj@aphis.usda.gov) - USDA/APHIS, Washington, DC;
Rudyj, Pimpa;
Scott, Simon (sscott@clemson.edu) - Clemson University;
Sudarshana, Mysore (mrsudarshana@ucdavis.edu) - USDA-ARS;
Susaimuthu, James (james.susaimuthu@wsu.edu) - Washington State University;
Tzanetakis, Ioannis (itzaneta@uark.edu) - University of Arkansas;
Vidalakis, Georgios (vidalg@ucr.edu) - University of California-Riverside;
Zhang, Shulu (shulu@agdia.com) - Agdia, Inc.

Brief Summary of Minutes

WERA-20 Annual Meeting

McMenamins Kennedy School, 5736 NE 33rd Ave., Portland, Oregon

July 11-14, 2011

The meeting was called to order at 1:00 PM by chairman, Joseph Postman. Minutes were to be taken by Simon Scott who volunteered to host the next annual meeting in South Carolina on some date in 2012 that takes into account the potential diseases, temperature, and humidity. Participants introduced themselves and Ralph Cavalieri provided a few comments as the administrator of the project. He gave a brief explanation of the role and function of WERA 20. The hatch act authorizes 25% of the funds for multistate research. WERA 20 is a coordinating committee in which people with similar research interests can co-ordinate efforts. It is less restricting than formal research projects. The committee rewrites its project every 5 years. WERA 20 has been rewritten and the project is approved from October 2011 to September 30th, 2016.

Administrators at NIFA are not sure of the outcome of current budget negotiations. The house cut 12-13% from the budget however it is expected that the senate will reinstate these funds.

State Reports began: Brief synopses of the information are presented in the minutes and may be supplemented by the annual reports from individual states.

Lydia Clayton/Alex Karasev, Idaho.

Reported on surveys of viruses in grape vines completed over the past 3 years. There are approximately 1600 acres of grape vines in Idaho with about 25 of these being located in Northern Idaho. The industry was the first to be established in the west in 1864 but then disappeared because of Prohibition and began to re-establish itself in 1970. An initial survey of viruses completed in 2008/2009 by Karasev, Martin, and Rayapati detected Leaf Roll (3) and the rugose wood complex in both Northern and Southern Idaho. A survey by ISDA indicated that only the grape mealy bug (Pseudococcus maritimus) and not the vine mealy bug (Planococcus ficus) were present in the state.

2009 survey 100 samples from 7 counties, 2,000 individual tests coordinated with the ISDA survey. 6% of samples infected with one or more grapevine leaf roll viruses also the virus was detected in 1 sample that had been collected from 25 retail nurseries. No grapevine fan leaf virus was detected. Grape mealy bug exists everywhere. Infestations of immature and adult females have been observed.

2010 survey 15 vineyards plus 1 abandoned property, 170 leaf samples Grapevine leaf roll 3,4, and 5 detected. Also Grapevine A, Grapevine B and Rupestris stem pitting associated virus. The nepoviruses Arabis mosaic virus and Grapevine fanleaf were not detected.

Certification regulations are being revised as the current regulations date from the 1970s.

Elina Coneva, Alabama

Surveys of blackberry viruses were completed in 2007- 2008. In 2007 15 sites in 8 counties. TRSV, ToRSV, RBDV, and INSV detected. All 4 viruses in almost all sites. Cultivar Navaho 60% multiple infections. Difficult for growers to find good plants.

2008 - 2010 Xylella fastidiosa bacterial leaf scorch of blueberry, also citrus variegated chlorosis in citrus in Albama recorded. Sharpshooter vectors (Homalodisca vitripennis ) present. Botryosphaeria dothidea stem blight of blueberry present in up to 40% of plants. Participated in an E Extension grant working with LA, USDA, MS, NC. Thishas produced the website www.extension.org/blueberries.

Ken Eastwell, Washington

Described work on Cherry leaf roll virus (CLRV), Little cherry virus and rusty mottle virus. CLRV was first detected in cherry in WA in 1998. It developed from the initial find to an industry-wide problem that continues to spread. Transmission is not well defined. In other species (Walnut) it is pollen-borne. In cherry there appears to be a single infection followed by rapid localized spread through root grafting. The type of irrigation used affects the incidence of the virus. 2006 -2007 pollinated large numbers of flowers but although the virus could be detected in 27-50% of the pedicels there was no movement to the tree. It is possible that the presence of a second virus (PNRSV ?) is needed to facilitate transmission. In Franklin County 83 out of 95 samples were positive this year. The rootstock Colt is hypersensitive to CLRV but Colt does not produce good trees.

Bing and Sweet Heart Constitute 61% of the trees in WA.

Little cherry virus 2 was widespread in 2010 and trees showed symptoms. This was repeated in 2011. LCV 2 is transmitted by the apple mealybug. However the grape mealy bug is moving from the south and it is a vector of Grapevine Leaf roll 3 which is closely related to LCV 2 at the molecular level.

Necrotic Rusty mottle has been showing enlarged veins in some hosts.

Brook Edmonds, Oregon Dept of Agriculture

Brook introduced herself as the replacement for "Sid" Sedegui. The testing for fruit tree viruses is being completed using ELISA, not the molecular probes favored by Sid.

Ramesh Pokharel, University of Colorado, Grand Junction.

Described work on Cherry rasp leaf virus (CRLV) in conjunction with Ray Mock at USDA, Beltsville. He reported a finding of CRLV on sour cherry and noted suckers originating from removed trees that displayed the classic symptoms of rasp leaf disease. Surveys had been completed in 2009 and 2010. CRLV present in 62% of the samples. Cherry virus A present in 53% of the samples. Analysis of the sequences of PCR amplicons showed little variation among isolates of CRLV. CRLV was also detected in asymptomatic trees. He also reported on a rootstock , variety, and management trials of CRLV.

Lauri Guerra, Washington Dept. of Agriculture, Prosser

John Hu University of Hawaii, Honolulu

John described work with Citrus Tristeza virus in Hawaii. Citrus has been grown in Hawaii since 1792. Citrus tristeza stem-pitting was first seen in 1952. The Brown citrus aphid vector of CTV is present in Hawaii. Citrus has become more important as land used previously for growing sugar cane and pineapple has become available and a replacement crop is needed. Both the decline form and stem pitting forms of CTV are present in Hawaii. The incidence of the virus was determined using PCR and tissue-blot immunological assays. CTV is widespread with an overall incidence among the islands of approx 75%. Samples were tested using specific PCR primer pairs to identify the T3, T30, T36 and VT genotypes of the virus. A CP transgene was constructed using sequences of isolates from Hawaii and other countries and was predicted to be effective against 95% of all reported isolates. This was used in a multiple post transcriptional gene silencing system to control the virus using Mexican Lime as the host into which the transgenes were inserted. 58 plants are being tested for resistance and are being challenged using 5-10 brown citrus aphid per plant to inoculate the virus.

Ruhui Li, USDA-ARS, Beltsville, Maryland

Gooseberry vein-banding disease has been associated with 3 possible viruses: members of the genera Clostero - Rhabdo and Badna. Goosebery vein-banding virus is a distinct species in the genus Badnavirus. Jonkheer-Van-tets is a better indicator for GVB than Amos Black. Lui reported on pathogen elimination in tissue culture describing the elimination of Cherry Virus A by using Ribavirin in culture medium. Peach latent mosaic viroid could also be eliminated in tissue culture using ribavirin.

This session finished at 5:00 PM and dinner was served at 6:00 PM.

Wednesday 13th July.

Field trip to Hurst berries, packing fresh berries; North American Plants - Tissue culture facility, Sokol Blosser Vineyard and Winery, Dundee, Oregon - Lunch and wine tasting, Oregon State Field station - Blueberry Field day.

Thursday, 14th July, 2011.

Margarita Licha , USDA-APHIS, Beltsville, MD

Provided a review of her program at Beltsville. Post entry quarantine for pome and stone fruits is available for material from only 5 countries in Europe. In 2010 the program received 13 Pome accession s and 62 prunus accessions under this program. Most of these were from the Netherlands. The pathogens found in Prunus were Prune dwarf virus, Prunus necrotic ringspot virus and American plum line pattern virus Hop stunt viroid and Peach latent mosaic viroid. 209 releases of material were made in 2010 Total of 789 releases from the program since 2007. A recipient of a release has to approve destruction of material maintained at Beltsville. Thus material has to be maintained in Beltsville until this approval is received.

Bob Martin USDA-ARS, Corvallis, OR.

Described work on Blueberry necrotic ring blotch virus aka "Funky spot". The virus occurs in both Highbush and Rabbiteye blueberries. It was formerly thought to be caused by a Septoria but the rings occur on both surfaces of the leaves. It has been detected in GA, NC and SC. There is transmission in the field. Plants do not show symptoms during early stages of growth but they appear later in the season. The virus has a multipartite genome with 4 RNAs. Other viruses mentioned were: Raspberry leaf mottle virus (a closterovirus that is aphid transmitted), Raspberry latent virus a novel reovirus, Rubus yellow net virus (a badnavirus). Blueberry premature fruit drop disease spreads in British Columbia. It cause 100% fruit drop. There is a cryptic virus associated with plants infected with the disease but it is probably not the causal agent. Blueberry mosaic virus is a putative Ophiovirus, and Blueberry bronze leaf curl disease is associated with a tentative closterovirus.

Carol Masters Canadian Food Insp. Agency, Sidney, BC

The PPV program in Canada is no longer an eradication program. Henceforth it will be a management program. Funding was not received until June 2011. This year 20,000 samples will be collected: a reduction from the 120,000 samples of previous years.

PPV-W has a host range almost identical to PPV-D but P. persica is a reluctant host and the virus does not infect nectarine. Grapevine A was detected in material imported from France.

Joseph Postman, USDA-ARS, Corvallis, Oregon.

Described work on Medlar (Mespilus germanica L.) in which ACLSV produces ringspot symptoms. Medlar may be immune to Apple stem pitting virus. Cherry leaf roll virus in elder berry was discussed. A previous report of Apple mosaic virus in pears was refuted. The symptoms were associated with Pear vein yellows.

Erich Rudyj , NCPN Riverdale, Maryland

Presented the current status of the National Clean Plant Network.

Simon Scott, Clemson University, Clemson, South Carolina

Refered to continuing work on the viruses and viroid present in Ta Tao 5 germplasm. The germplasm has been used to achieve a significant bloom delay in peach in the southeastern USA but the relative contribution to the delay of the 2 viruses and the viroid infecting this germplasm is still being determined. Phony Peach Disease associated with Xylella fastidiosa is re-emerging as a problem in some areas of SC. The range in which the disease typically occurred is expanding. The bacterium cannot be detected by either RT-PCR or Real-time PCR in a proportion of the trees displaying classic symptoms (luxuriant growth and a flat top). Research is ongoing to determine the distribution of the bacterium in the tree. Previously researchers have suggested that the bacterium occurs at higher concentrations in root tissue.

Sudhi Sudarshana (mysore.sudarshana@ars.usda.gov) USDA-ARS, Davis, California.

Presented the results of a Grape vine leaf roll survey completed at Davis by Rodrigo Almeida. The majority of isolates examined were GRLV 3. He then described his work on Almond Brown Line and several phytoplasmas causing distinct disease in stone fruit. He also reported on work with Cherry stem pitting disease.

James Susaimuthu (James.Susaimuthu@wsu.edu) Washington State University.

Described the proposed increase in fees for testing and therapy at Prosser. There is a new webpage www.healthyplants.wsu.edu associated with work at WSU.

Yannis Tzanetakis (itzaneta@uark.edu) University of Arkansas.

Provided information on viruses in Blackberries. There are 9 new viruses reported in Blackberries in the south east. These include Blackberry Virus E a flexivirus related to the Allexiviruses, also an emaravirus, a new Ilarvirus, a fovea-like virus, a picorna-like virus, and possibly an ophiovirus. With recent discoveries there are becoming too many viruses in small fruit for which to test: over 40 viruses in Rubus species, over 27 virus in strawberry, and 11 viruses in blueberry.

Georgios Vidalakis (vidalg@ucr.edu) UC Riverside, California.

Provided a description and update of the Citrus program at Riverside. His work has involved looking at viroids as transmissible small nuclear RNAs (TsnRNAs) that affect tree growth and morphology, work with citrus porosis virus, and using indirect approaches (detection of proteins secreted by the pathogen-Spiroplasma citri) rather than detection of the pathogen itself.

Shulu Zhang (shulu@agdia.com) Agdia Inc., Elkhart, Indiana

Gave a presentation on the use of recombinase polymerase amplification (RPA) for the detection of Plum pox virus.

The meeting adjourned at 5:00 PM on July 14th, 2011.

Minutes respectfully submitted by S.W. Scott, Clemson University

To view individual reports, go to the Homepage of WERA-20 and look in the Additional Documents section at: http://lgu.umd.edu/lgu_v2/homepages/home.cfm?trackID=13496

Accomplishments

Collaborations built through WERA-20 continue to drive high profile grants funded under the Specialty Crops Research Initiative and the National Clean Plant Network. Research completed among collaborators in WERA-20 provided information on the incidence, distribution and epidemiology of viruses in fruit trees, small fruits, and grapevines. For example, an occurrence of Blueberry shock virus in Michigan was dealt with as a result of information developed by collaborators on the west coast. Information on the occurrence of viruses in the vineyards of the west coast allows growers to address problems associated with viruses and provides information on the sources of virus in the nursery industry. The problems with viruses in blackberry and blueberry (Blueberry necrotic spot virus Funky spot disease) in the southeastern US, where expertise is lacking, are addressed through collaborations with researchers in Arkansas and Oregon.

Publications

Coneva, E., J. Murphy, and R. Boozer, and N. Velasquez. 2010. Incidence and distribution of viruses in blackberry (Rubus sp.) in Alabama. International Journal of Fruit Science 10:87-95. Coneva, E., J. Murphy, R. Boozer, N. Velasquez. 2008. First report of Tobacco ringspot virus in Blackberry (Rubus sp.) in Alabama. Plant Disease 92:1708. Donglin Xu , Ray Mock , Gary Kinard , and Ruhui Li. 2011 Molecular analysis of the complete genomic sequences of four isolates of Gooseberry vein banding associated virus . Virus Genes 43:130-137. Eastwell KC, Villamor DV, McKinney CV, Druffel KL. 2010. Characterization of an isolate of Sowbane mosaic virus. Archives of Virology 155:2065-2067. Gibson, P.G. Reighard, G., Marini, D., and Scott, S.W. (2010). Effects associated with graft-transmissible agents found in peach variety 'Ta Tao 5'. Julius-Kuhn-Archiv. 427:284-288. James, D., Varga, A., Leippi, L., Godkin, S., and Masters, C. 2010. Sequence analysis of RNA 2 and RNA 3 of Lilac leaf chlorosis virus: a putative new member of the genus Ilarvirus. Archives of Virology. 155:993-998. James, D., Croft, H., Malinowski, T., and Reed, C. 2009. Production of antisera and evaluation of serology-based techniques for the detection of Blackcurrant reversion virus. 21st International Conference on Virus and Other Graft Transmissible Diseases of Fruit Crops. Neustadt, Germany, July 5 - 10, 2009. JKI Annual Report 148:21 (Abstr.). Karthikeyan, G., Alabi, O.J., and Naidu, R.A. 2011. Occurrence of Grapevine leafroll-associated virus 1 in two ornamental grapevine cultivars in Washington State. Plant Disease 95:613. Kim, B.T., Gibson, P.G. and Scott, S.W. (2010). Expression of the coat protein genes of PNRSV and PDV in the synergistic disease peach stunt. Julius-Kuhn-Archiv. 427:114-117. Li, Ruhui , Mock, Ray , Fuchs, Marc , Halbrendt, John , Howell, Bill and Liu, Zongrang (2011) Characterization of the partial RNA1 and RNA2 3' untranslated region of Tomato ringspot virus isolates from North America', Canadian Journal of Plant Pathology, 33:1, 94-99. Liming Lin, Ruhui Li, Ray Mock, Gary Kinard, 2011. Development of a polyprobe to detect six viroids of pome and stone fruit trees. Journal of Virological Methods 17: 91-97. Ma, X., Coneva, E., H. Fadamiro, J.F. Murphy, Charles Ray, and F. Dane. 2010. Seasonal occurrence and abundance of sharpshooter leafhoppers in Alabama Orchards and Vineyards. International Journal of Fruit Science 10:341-354. Martin, R.R., Zhou, J. and Tzanetakis, I.E. 2011. Blueberry latent virus: An amalgam of the Partitiviridae and the Totiviridae. Virus Research 155: 175-180. Melzer, MJ, Sether, DM, Borth, WB, Hu, JS. 2011. Characterization of a virus infecting Citrus volkameriana (Ten. & Pasq.) with citrus leprosis-like symptoms. Phytopathology (accepted for publication) Melzer, MJ, Nelson, SC, Hu, JS. 201X. Tristeza and blight diseases of citrus in Hawaii. CTAHR Cooperative Extension Services publication (in preparation) Melzer, M.J., Sether, D.M., Alvarez, A, Hu, J.S. 2011. Huanglongbing CTAHR Cooperative Extension Services publication Quito-Avila, D.F., Jelkmann, W., Tzanetakis, I.E., Keller, K. and Martin, R.R. 2011. Complete sequence and genetic characterization of Raspberry latent virus, a novel member of the family Reoviridae. Virus Research 155: 397-405. Sabanadzovic, S., Abou Ghanem-Sabanadzovic, N. and Tzanetakis, I.E. 2011. Blackberry virus E: an unusual flexivirus. Archives of Virology 156:1665-1669 Schilder, A. Blueberry Scorch Virus. Regional pest Alert, USDA NIFA Integrated Pest Management Program, the North Central IPM Center and the Land Grant Universities. Schilder, A. Blueberry Scock Virus. Regional pest Alert, USDA NIFA Integrated Pest Management Program, the North Central IPM Center and the Land Grant Universities. Tzanetakis, I.E., Martin, R.R., Scott, S.W. 2010 Genomic sequences of Blackberry chlorotic ringspot virus and Strawberry necrotic shock virus and the phylogeny of viruses in subgroup 1 of the genus Ilarvirus. Archives of Virology 155:557-561

Impact Statements

The perennial specialty crops covered by the WERA-020 project contribute a significant proportion of the profits generated by U.S. agriculture with a farm gate value of $18 billion (NASS, 2008). Clean plant programs continue to facilitate the release of germ accessions from foreign sources in 2011, providing access to valuable material for nurseries and growers, and for crop improvement. Virus-tested propagating material from state and national programs allow growers to initiate new plantings with the highest quality plants available and potentially maximize the yield obtained throughout the life of the crop.
WERA-020 effectively fostered collaborations that led to significant advancements in virus disease management. A new virus was found to be the most widespread pathogen of blackberries and, with data gained by a team of scientists, control methods are being implemented. Similarly, past successes in discerning biological parameters of blueberry diseases has resulted in effective control programs in several states including Michigan, Washington and Oregon. Research completed by WERA scientists continues to identify previously undocumented viruses that contribute to yield losses in many crops. In Blackberries infections by a single virus are commonly asymptomatic whereas infections by more than one virus induce the expression of symptoms. The impact on yield and crop longevity of single infection versus a double (multiple) infection may be a significant factor in the choice of material made by a grower should high quality virus-tested material of a particular cultivar is not available.