Brief Summary of Minutes of Annual Meeting

WERA – 20 Meeting Minutes

Virus and Virus-like Diseases of Fruit Trees, Small Fruit and Grapevines

North Carolina State University Club

Raleigh, NC

July 17-19, 2017

Monday, July 17

Field Trip

Twenty two people (visitors and locals) attended the field trip. The Horticultural Crops Research Station in Castle Hayne, NC was visited. Bill Cline hosted a tour of the station where muscadine grapes and blueberry research plots were observed. Discussion about muscadine grapes and blueberry viral diseases was led by Bill Cline and Bob Martin while observing some symptoms on plots. After lunch at Wrightsville Beach, the group headed to Rose Hill to tour and wine tasting at Duplin Winery. Muscadine grapes wine production was this winery’s signature. Schedule below was followed.

8:00     Bus leaves Raleigh

10:00   Arrive at Horticultural Crops Research Station in Castle Hayne – Host Bill Cline

Tour of the station: blueberry and muscadine grapes research plots

11:30   Leave the station for Lunch in Wrightsville Beach

12:00   Lunch at Oceanic Restaurant

2:00     Bus heads to Rose Hill

3:00     Tour of production facilities and wine tasting at Duplin Winery

5:00     Bus leaves for Raleigh

7:00     Bus returns to Ramada Hotel, Raleigh

Tuesday, July 18

8:30     Welcome

Forty people attended the first day of the WERA-20 meeting at the North Carolina State University Club.

James Moyer (Washington State University)

Jim opened the meeting with welcome and opening remarks.

Steve Lommel and Eric Davis (North Carolina State University)

Steve and Rick followed up with welcoming remarks from the College of Agriculture and Life Sciences (CALS), NCSU and the Department of Entomology and Plant Pathology (DEPP), NCSU.

Christie Almeyda (Micropropagation and Repository Unit - MPRU, NCSU)

Christie served as the chair of the meeting. She welcomed everyone to the meeting, discussed housekeeping topics and introduced the first speaker.

9:00     Scientific presentations / State and Federal Reports

Allison Gratz (Center for Plant Health, Canadian Food Inspection Agency – CFIA, Government of Canada)

‘CFIA Center for Plant Health - Sidney Laboratory Update 2016-17’

Allison provided an overview of the program, plant material and regulations. Detections by diagnostic unit in Malus spp., Pyrus spp. and Prunus spp. from 2013-2016 in samples collected from certified sources were presented. A test for Cherry Virus A (CVA) was validated and the Centre used heat therapy to eliminate the virus from G1 repository. Currently there is no CVA-infected selections remaining in the virus-certified collection. From Mike Rott’s lab, CFIA has learned that NGS is a valuable and effective tool. Allison talked about the approved project for 2017-2019: ‘Validation and implementation of next generation sequencing technology for routine testing in the Sidney Laboratory Diagnostic Unit’ and its main goals.

Ruhui Li (USDA-ARS, Beltsville, MD)                       

‘Discovery and Molecular Characterization of Luteoviruses Infecting Fruit Trees’

Ruhui provided an overview of the discovery and molecular characterization of Apple Luteovirus 1 (ALV-1), a new luteovirus detected by HTS and found in rapid/sudden apple decline disease. Samples were collected at different seasons to determine the best time for sampling. The virus titer was different among trees, varieties and seasons. Transmission studies were also carried out.

Bob Martin (USDA-ARS, Corvallis, OR)

‘A Quest for Raspberry Leaf Curl Disease’

Bob provided an update for his investigations on Raspberry Leaf Curl Virus, Grapevine Red Blotch Virus and Blueberry fruit drop-association. Raspberry leaf curl virus is the only virus that requires biological indexing for export of plants from the US. All data has been collected after NGS studies. There is no detection method yet in place for this virus. Studies on Grapevine red blotch field transmission were done to identify when the virus is actually being spread in the field to inform pest management options for controlling the vector(s) of the pathogen. Blueberry fruit drop-associated virus (BFDaV) is a caulimovirus previously described affecting ‘Bluecrop’ only. The virus was not detected in other blueberry varieties planted adjacent to blocks of ‘Bluecrop’ with BFDaV infection. The disease has been observed only in northern Washington and British Columbia. Growers are actively tagging and removing plants while BFDaV has been added for testing of G1 plants.

Joseph Postman (National Clonal Germplasm Repository USDA-ARS, Corvallis, OR)

‘Pathogens Impacting Corvallis USDA Germplasm Collections Management – 2017’

Joseph provided an overview of collections with issues including hazelnut, blueberries, red currants, pear, elderberry and black currants. Apple mosaic virus (ApMV) was eliminated from more than 25 infected hazelnut cultivars using heat therapy and shoot-tip grafting. However, the virus was detected in five infected field trees in 2015. Blueberry shock virus showed a higher incidence in 2016. Tomato ringspot virus (TomRSV) was confirmed by ELISA in red currants. Xyllela fastidiosa was causing significant problems in olive trees in Europe. It was first identified in pear in Oregon. Xyllela is widely distributed in a variety of hosts. Pierce’s disease of grape is caused by a different isolate. Joseph provided an overview of surveys conducted in 2016 and despite multiple positive ELISAs, the pathogen was not confirmed by PCR determining this situation as a ‘fake disease’ that led to resume normal operations in 2017. Black currant reversion virus has a very low risk of spreading.

Dipak Poudyal (Plant Health Program, Oregon Department of Agriculture, Salem, OR)

‘Virus Survey in Fruit and Berry Crops in Oregon’

Dipak presented an overview of fruit tree nurseries in certification programs (latent virus survey in pome fruit nurseries and ilarvirus survey in stone fruit nurseries), virus survey in orchards (plum pox virus survey in stone fruit orchards and grapevine red blotch virus in vineyards) and an update of certification programs (harmonization of grapevine certification programs in the Pacific Northwest - ID, OR and WA - and updating caneberry certification standards in OR).                                     

12:00-1:30       Lunch

Ioannis Tzanetakis (University of Arkansas, Fayetteville, AR)

‘Arkansas Update’

Ioannis provided an overview of his investigations on viruses in Arkansas, including Peach rosette mosaic virus for which a PCR test has been provided using a UTR’3 region; Black currant ideovirus for which a detection test has been developed based on conserved regions of both RNAs; Blackberry leaf mottle virus associated virus and Black currant virus A.

John Hu (University of Hawaii, Honolulu, HI)

‘Virology Research in Hawaii’

John presented an overview of his investigations on Taro vein chlorosis virus (TaVCV) to better understand the diversity of the virus in the region, develop molecular and serological detection assays, identify the vector and develop effective management options for farmers. Low genetic diversity observed in Hawaiian isolates further support the fact that the virus was introduced recently. Improved assays for virus detection were developed, providing better tools for virus surveys, monitoring and surveillance, plant quarantine and germoplasm screening. John presented strong evidence to support that taro planthopper is a vector of the virus.

Shulu Zhang (Agdia Inc. Elkhart, IN)           

‘Updates on Rapid Detection of Plant Pathogens by Isothermal AmplifyRP®’

Shulu presented an update on the rapid detection of pathogens using isothermal AmplifyRP. Agdia’s different formats for AmplifyRP can be used for different endpoint applications and for different pathogens. The kits are fast, simple, sensitive and specific.

Maher Al Rwahnih (Foundation Plant Services – FPS, University of California, Davis, CA)

‘Pistachio Metagenomics’

Maher presented an overview of his investigations of an off-type pistachio line showing stunted symptoms and bushy-top syndrome caused by Rhodococcus fascians. A high throughput sequencing (HTS) based discovery method was carried out to identify and characterize viral pathogens in pistachio cultivars showing stunting symptoms. The National Clonal Germoplasm Repository pistachio collection was evaluated to assess the disease status. Pistachio Ampelovirus A (PAVA) and Citrus bark cracking viroid (CBCVd-pistachio) were found in these studies as novel species within the Closteroviridae and Pospoviroidae, respectively. Both viral agents (PAVA and CBCVd-pistachio) are graft transmissible.

2018 Location

Christie discussed the location for next year’s meeting. Bob Martin proposed Oregon for the next meeting location and everyone seconded the motion. Dates for the meeting TBD.

Wednesday, July 19

NGS Session

Maher Al Rwahnih (Foundation Plant Services (FPS), University of California, Davis, CA)     

Case Study 1: ‘Limiting Factors in the Detection of Plant Viral Pathogens Using HTS’

Maher presented an overview of the HTS current applications at FPS including study diseases of unknown etiology, metagenomics virome analysis, re-sequencing of known viruses, host-pathogen interaction studies and post-entry quarantine procedures. Technical challenges and establishment of biological significance were indicated as HTS limitations. Maher discussed about the importance of Koch’s postulates while using HTS-based data for virus discovery. Maher stated that we are all in need of standard protocols/minimal requirement for HTS use as well as to establish a framework for the evaluation of risks posed by new viruses discovered by HTS.

Sudarshana Mysore (USDA-ARS, University of California, Davis, CA)

Case Study 2: ‘Dealing with the discovery of new viruses by deep sequencing in perennial crops: a tale of two viruses’

Sudhi presented an overview of grapevine red blotch virus discovery, surveys and impact as well as discovery of a luteovirus in nectarine trees in post-entry quarantine. He emphasized the importance of time of releasing information to stakeholders.

Shailaja Rabindran, Yilmaz Balci and Pauline Spaine (USDA-APHIS, Riverdale, MD)

APHIS presents NGS policy challenges, gaps in scientific knowledge, permits, PRAs, data collection for pests/pathogens

Shaila presented an overview of the actual relationship status between scientists and regulators. HTS is not used as a routine diagnostic tool. There is no requirement to use HTS to export certification. Mark discussed the importance of infrastructure and bioinformatic facilities to develop import policy. Standardization of protocols as well as developing of better diagnostic for imported plants are crucial.

Discussion, Conclusions and Next Steps

Erich gave an overview of the NCPN program, history and crops the program is serving. He pointed out that advocating to increase funding is a work in progress. Main areas for the centers to focus on are laboratory quality controls, economically studies and outreach (growers/stakeholders).

Maher started the discussion about the 2015 WERA-20 meeting purpose: to bring together the scientific and regulatory community to engage in the start of a conversation around NGS and the use of this technology to find pathogens and/or certification purposes. The 2016 WERA-20 meeting served as a platform for the establishment of biological significance of HTS findings. In this year's meeting, the goal is to take action and move forward. Maher and Shaila discussed the harmonization project as a joint effort to standardize minimal steps. Phil stated that the purpose of this initiative is to have standardized protocols. Maher stated that it is imperative to accelerate the process of quarantine. Bob suggested that a proposal be submitted within five weeks (Deadline 08/18/2017) to have a working group for a proficiency test (developing SOPs) and validation. After the procedures are in place, the next step would be to offer a workshop to train people about the SOPs.

Maher brought up other challenges including: naming novel viruses, releasing of sequences, and publishing. He claimed that following the classical way of naming new viruses (using symptoms associated to the disease) might not be a good idea since there is an impact of the name of the new virus on stakeholders. Ioannis and Shaila pointed out that breeders move material all over and there are no restrictions. They discussed the importance of having permits. Regulators can only regulate viruses of which they are knowledgeable. If there is no disease associated with a material, there is no authority to regulate. Regulators have a system of checks and balances that need to be performed for a disease to be regulated. Joseph discussed the issue of formalizing positive controls collections to NCPN center

CFIA, Center for Plant Health, Government of Canada (Allison Gratz and Anna-Mary Schmidt)

Quarantine and Diagnostic Activities

Samples from Foreign Certification Programs

The Centre for Plant Health continues to test a sampling of accessions taken from grapevine and tree fruit shipments from Canadian approved foreign certification programs in the United States, France and Germany for grapevines, and the United States, France, Belgium, Germany, Netherlands and United Kingdom for tree fruit.

In 2016, 20 grapevine accessions were tested (60 vines of each accession) and the only detection was Arabis mosaic virus in a grafted variety from Germany. This virus is not regulated in Canada. Over the past five years, there has been a decrease of virus detections in grapevines coming from approved certified foreign sources. In 2016, 29 tree fruit accessions were tested from approved sources in the United States (Washington, Oregon, and Pennsylvania). No viruses were detected in Malus spp. samples, Apple chlorotic leaf spot virus and Apple stem pitting virus (ASPV) were detected in the single Cydonia sp. sample, ASPV and Pear blister canker viroid were found coinfected in one Pyrus sp. sample, Prune dwarf virus was detected in one Prunus sp. sample, Little cherry virus-1 was detected in two samples, and Cherry virus A was detected in 75% of the Prunus samples. None of these viruses are regulated in Canada.

Samples from other sources

Non-certified material is also accepted and tested, and must be routed directly to the Centre for Plant Health PEQ facility for a full range of testing before release. This material includes imports from non-approved foreign sources or domestic breeding programs. Fifteen new grapevine accessions, two Pyrus spp., 12 Prunus spp., and 21 Malus spp. were received and tested in 2016. The Centre for Plant Health does a limited amount of regulatory testing for virus and virus-like diseases of small fruit (berries). The testing requirements for imports are determined on a case-by-case basis depending on the origin of the material. Since Canada does not have a national small fruit certification program for exports, all testing for export is also done on a case-by-case basis depending on the requirements of the importing country. In 2016, three varieties each of Fragaria and Rubus imported from France were tested, as well as one Fragaria variety from the Netherlands. No viruses were detected. Sixteen varieties of Rubus destined to the USA were tested for Rubus stunt phytoplasma, and there were no detections of this pathogen.

Cherry virus A (CVA) update

Since 2003, when a test for the latent virus CVA was validated, the Centre for Plant Health has worked to eliminate it using heat therapy from our Generation One repository. Currently we can report that no CVA-infected selections remain in the virus-certified collection.

Tissue Culture

The tissue culture facility at the CFIA Sidney Laboratory supplies virus-free root stock and indicator plants for field and greenhouse woody bioassay testing. Upon request, the facility may produce small numbers of Generation 1 tissue culture initiates, from the CFIA’s tree fruit and grapevine virus-tested repository, for domestic or international distribution. This facility also receives and maintains tissue culture plants from international sources for inclusion in the CFIA Sidney Laboratory’s virus testing program. The tissue culture facility plays an integral part in the virus elimination service of the Sidney Laboratory. Virus elimination, when requested, is conducted on grapevine varieties using meristem culture following in-vivo heat therapy of infected plants, and virus elimination of small fruit and tree fruit varieties occurs with meristem or micro-shoot culture following in-vivo heat therapy.

Next Generation Sequencing

In early 2017, Anna-Mary Schmidt received funding for a two-year project to transfer NGS technology from research to the Sidney Laboratory Diagnostic Unit. The objectives of the project are to (1) transfer NGS technology from the Sidney Laboratory Research Unit to the Diagnostic Unit for routine testing of viruses and viroids in grapevine, tree fruit, small fruit and other horticultural crops, (2) validate the NGS method in the Diagnostic Unit, (3) develop a diagnostic workflow, and (4) implement NGS technology as an official test method under the Sidney Laboratory’s Quality Assurance System (ISO 17025: General Requirements for the Competence of Testing and Calibration Laboratories). Also, plans for the implementation of a domestic clean plant network for tree fruit and grapevines centred on next generation sequencing (NGS) methods are underway.

New Researcher

Harvinder Bennypaul joined the Centre for Plant Health as a new research scientist in August 2016. His research interests include development of diagnostic methodologies, molecular characterization and management of plant pathogens.

Pome/Prunus Fruit Tree Quarantine Programs, Plant Germplasm Quarantine Program, USDA, APHIS, PPQ, FO (Joseph Foster)

In 2017 the Pome quarantine program had the following types of releases: final releases for 25 Malus; 22 Pyrus, 12 quinces, as well as provisional releases for 7 Malus and 1 Pyrus. The Prunus quarantine program had 32 final releases as well as 12 provisional releases. The Prunus seedling program had 229 final releases. The total number of fruit tree releases for 2017 is 340. Last January, Dr. Margarita Bateman accepted a promotion to join the Plants for Planting Policy group in Plant Health Programs at PPQ Headquarters in Riverdale, MD. She made many noteworthy contributions during the 10 years she worked on pome and stone fruit introductions as Team Leader for those crops.

Accessions in testing

Prunus

In 2016, Tom Kim, Horticulturist for Prunus, received and established 36 accessions itemized as follows: 3 P. salicina accessions from South Africa; 4 P. armeniaca from France; 9 P. persica accessions from Valencia, Spain; 10 cherry accessions, including 1 P. campanulata, 1 P. cyclamina, 1 P. pendula, and 1 P. sargentii from The United Kingdom; 6 P. armeniaca   from France; 4 P. domestica from Germany. During 2016 we had more than 300 Prunus accessions in quarantine at Bldg 580.

Pomes

In 2016, Robert Jones, Pomes Crop Specialist, received and established a total of 41 accessions itemized as follows: 21 cider apple accessions and 4 cider pears from The United Kingdom, 1 Malus trilobata from Scotland, UK; 2 accessions (rootstocks) from Brazil, 3 accessions (rootstocks) from South Africa, and 10 apples from France. During 2016, we had more than 400 apples, pears and quinces in quarantine at Bldg 580.

Pathogen interceptions

Every year we detect pathogens in imported pome and stone fruits. Testing is done using indicators, ELISA serology, and PCR/RT-PCR procedures. Shipments may contain more than 50% infected accessions. Regular detections include the common latent viruses in pomes, cherry virus A in cherries, little cherry virus 2 in flowering cherries, peach latent mosaic viroid in peaches, and ilar viruses (PNRSV & PDV) in all Prunus. Notable recent detections include pear blister canker viroid in pears, hop stunt viroid in 2 peaches, a plum and an apricot, little cherry virus 1 in a plum from the Republic of Georgia, plum bark necrosis stem pitting associated virus in 11 Chinese peaches, nectarine stem pitting associated virus in 4 peaches from France, a phytoplasma in a cherry from UK, and new luteoviruses in pome and stone fruits detected by Dr. Ruhui Li. Trees that test positive are sent to thermotherapy.

Therapy

Different heat treatment and tip grafting or tissue culture procedures are used to obtain pome and stone fruits free of detected pathogens. Moving all of the infected accessions through the therapy process efficiently has been the greatest challenge for these quarantine programs.

Richard Slocum, Tissue Culture Scientist, continues to establish accessions in tissue culture in order to put them through therapy. In the past, he has made excellent progress with apples, pears, peaches, plums and cherries to the extent that these fruit trees are routinely exposed to in vitro thermotherapy. His latest accomplishment has been to establish tissue cultures of almonds and keep them for several growing seasons in tissue culture. At this time he will continue working on the survival of the material post therapy, which has proven to be challenging.

Collaborations

Dr. Ruhui Li, Dr. Gary Kinard- USDA-ARS: New PCR procedures and NGS

Dr. Maher Al-Rwahnih and Dr. Deborah Golino, FPS, Davis, CA: NGS procedures

Dr. Scott Harper, NCPN-FT, Prosser, WA: Detection of new Prunus viruses & field testing of pomes

Allison Gratz and Dr. Mike Rott, Agriculture Canada: NGS protocols in use in Canada and field testing of pomes

New personnel at PGQP

Martha Malapi-Wight, Ph. D. is the new Lead Plant Pathologist for the Poaceae Quarantine Programs. Dr. Malapi-Wight joined PGQP in December 2015. She will be working on the quarantine programs for her assigned crops, as well as assisting PGQP with the implementation of NGS for diagnostics for quarantine purposes.

Ronald D. French, Ph. D. is the new Lead Plant Pathologist for the potato, sweet potato, and cassava quarantine programs. Dr. French joined PGQP in June. He will manage the quarantine programs for these crops, with the goal of introducing NGS for diagnostics.

USDA-ARS, Horticultural Crops Research Unit, Corvallis, OR (Bob Martin)

Our laboratory has been working on three projects this past year; 1. Blueberry fruit drop disease, 2. Grapevine red blotch virus and 3, Raspberry leaf curl disease. Some of these are in early stages of development, while others are much further along. A brief description of each follows.

1. Blueberry fruit drop disease: Blueberry fruit drop disease (BFDD) results in a nearly 100% fruit drop symptom in ‘Bluecrop’ blueberry, which persists year after year. The plants tend to be much more vigorous than adjacent plants, likely because they are putting very little energy into fruit production. The disease has been observed only in northern Washington and British Columbia to date, and in one cultivar of blueberry at the NCGR in Corvallis, Oregon that originated in Finland. Previously, we characterized a Caulimovirus, named Blueberry fruit drop associated virus (BFDaV), from infected plants that is almost perfectly correlated with the presence of symptoms (>95%). The virus was not detected in ‘Duke’, ‘Liberty’ or ‘Hardiblue’ blueberry plants adjacent to blocks of ‘Bluecrop’ with BFDaV infection. Growers are actively tagging and removing plants and I am optimistic that we can eradicate this virus from blueberry production in North America. We have added testing for BFDaV to testing of G1 plants.

2. Grapevine red blotch virus: The goal of this project is to determine when Grapevine red blotch virus (GRBV) is spreading in the vineyard. Knowing when the virus is spreading will provide important information on effective management of GRBaV and help focus the efforts to identify additional vectors. This information will also help target control measures to times of the season when the virus is being transmitted in the field. Three vineyards where GRBV has been spreading were used in 2016 and four vineyards are being used in 2017. One vineyard has an adjacent riparian zone, with most virus spread occurring near that edge of the vineyard nearest the riparian zone. In this case the trap plants are placed in a grassy area between the riparian zone and the vineyard. The second vineyard has an adjacent alfalfa field and since the one vector reported to transmit the virus is the Three Cornered Alfalfa Hopper, the plants were placed perpendicular to the alfalfa field, and within vineyard rows. This vineyard was removed after the 2016 season, and another nearby vineyard with GRBV was substituted for the 2017 field trials. The third vineyard has most spread adjacent to a recently disturbed wooded area. In 2017 a fourth vineyard was added to the study, adjacent to a grassy/wooded area, where GRBV movement has been observed. In each vineyard, every plant has a unique number and the location of each plant is being mapped so that where virus spread occurs in each vineyard can be determined. Fifteen plants are placed in each vineyard each month starting April 15 through Sept 15 in 2016; and starting May 2 in 2017 and continuing until October. After one month in the field the plants are returned to Corvallis, treated with a systemic insecticide and maintained in a screenhouse. All 300 plants were tested for GRBV in November 2016 and were negative for GRBV in PCR testing. After overwintering, a set of 90 plants that represented trap plants for the 2016 growing season were tested by PCR in May of 2017. Again, all plants were negative for GRBV. The entire set of 300 plants will be tested in Sept of 2017 and again in Sept. 2018. The plants from the 2017 trial will be tested in 2018 and 2019. This work aims to identify when the virus is actually being spread in the field to inform pest management options for controlling the vector(s) of the pathogen.

3. Raspberry leaf curl virus: Raspberry leaf curl virus (RLCV) is the only virus of Rubus species that requires a graft indexing result for plant export. This virus (disease) was reported to be widespread in the Great Lakes region in the twentieth century from 1920s to 1970s and aphid transmitted in a persistent manner. We collected wild raspberry from two locations in Wisconsin in 2014 and have identified a several novel in these materials, but this is from a very limited set of samples. We did more collections in Ontario and Quebec Canada, and Maine, Wisconsin and Minnesota in the U.S. in August of 2016. In July of 2017, collections were made in Washington, Montana, Idaho, Wyoming, British Columbia and Alberta. NGS analysis of several samples collected in 2016 revealed three novel viruses, two were cytorhabdoviruses and each was detected at a single location, the third is in the Luteoviridae and was more widespread. The Luteoviridae virus is aphid transmitted. In the collections we focused on wild raspberry since symptom expression in cultivars grown today is unknown. Part of the reason for doing these collections is that no one that we have contacted has an isolate of raspberry leaf curl disease in their collection. This project aims to develop a laboratory based assay for Raspberry leaf curl virus(es) to facilitate international movement of plant material, that is now limited by the requirement for biological indexing for this virus.

University of Arkansas, Fayetteville, AR (Ioannis Tzanetakis)

In collaboration with colleagues, several of which participate in WERA-20 we are working on the characterization and population structure of several viruses in blueberry, currant and blackberry. This information is used in the development of detection protocols that have the ability to detect the vast majority of isolates that circulate in the United States.

Certification

We have open channels of communication with both industry and regulators to optimize the guidelines so as to be implemented in the near future. We are completing a three-year study on the presence of blueberry viruses across major production areas in the United States, information that will be used for the development of a heat map on blueberry viruses and the roadmap for the diagnostic scheme in G2-G4 nurseries.

University of Hawaii (Michael Melzer, Wayne Borth, and John Hu)

Accomplishments

Taro vein chlorosis virus (TaVCV; genus Nucleorhabdovirus, family Rhabdoviridae) is a recent discovery in Hawaii that causes veinal chlorosis with a netted appearance, stunting and petiole streaking in taro (Colocasia esculenta). Plant death may occur in severe infections. Nucleotide and amino acid sequence comparisons and phylogenetic analyses revealed low levels of genetic diversity in the partial RNA-dependent RNA polymerase (RdRp) gene of 43 Hawaiian and 3 Palauan TaVCV isolates. This sequence information was used to design six new primer pairs targeting different regions of the RdRp gene. Primer set DCGF5/DCGR5 was identified as the most efficient of the six. Following optimization, highly sensitive and robust reverse transcription-polymerase chain reaction (RT-PCR) and immunocapture-RT-PCR (IC-RT-PCR) assays were developed. Localization of TaVCV in insect body parts essential for propagative, circulative virus transmission suggest that the taro planthopper, Tarophagus proserpina, is a vector of TaVCV.

Dasheen mosaic virus (DsMV) is one of the major viruses affecting taro production worldwide. We determined the genome sequences of two DsMV strains, Hawaii Strain I (GenBank:KY242358) and Hawaii Strain II (GenBank: KY242359), in taro from Hawaii. They represent the first genomic sequences of DsMV from the United States. Hawaii I and II had 77 and 85% identities respectively with other completely sequenced DsMV isolates. Hawaii I was most closely related to Vanilla mosaic virus (VanMV) (GebBank: KX505964.1), a strain of DsMV infecting vanilla in the southern Pacific Islands. Hawaii II was most closely related to DsMV isolate CTCRI-II-14 (GenBank: KT026108.1) in taro from India. Phylogenetic analysis of all available DsMV isolates based on their coat protein amino acid sequences showed some correlation between host plant and genetic diversity. Recombination analysis of full-length DsMV genome sequences was conducted. Our results showed that the recombination hotspots were mainly in the region of the CP and from C1 to NIa-Pro. To our knowledge, this is the first report of recombination events in DsMV. Both strains of DsMV were found to be widespread throughout the Hawaiian Islands.

Taro bacilliform CH virus (TaBCHV) is the second badnavirus found infecting taro, after Taro bacilliform virus (TaBV). We determined the complete genome of TaBCHV Hawaii strain (GenBank: KY359389) in taro from Hawaii and examined its occurrence and distribution. This is the first report of the occurrence of this virus in the United States. Alignment analysis showed the TaBCHV Hawaii strain has 93% and 94% sequence identity to China strains TaBCHV-1 and TaBCHV-2 respectively. Phylogenetic analysis based on the whole genome sequence of 21 selected badnaviruses, showed that the TaBCHV Hawaii strain clustered within the same branch as the two China strains. All sequences from available TaBCHV strains are most closely related to Piper yellow mottle virus (PYMoV; GenBank: NC022365) and are most distant from TaBV (GenBank: NC004450). We used RT-PCR to determine the incidence of TaBCHV on taro in Hawaii. Incidences of TaBCHV on the five islands were 72% on Oahu, 53% on Hawaii, 89% on Maui, 73% on Molokai, and 78% on Kauai, with a mean incidence of 73%.

Agdia Inc. (Shulu Zhang)

An update on rapid detection of viruses and viroids in fruit crops using isothermal AmplifyRP

AmplifyRP® is Agdia's isothermal amplification platform for rapid detection of plant pathogens using an advanced isothermal amplification technology – recombinase polymerase amplification. Up to now, Agdia is able to offer test kits in all three AmplifyRP formats – AmplifyRP Acceler8, AmplifyRP XRT and AmplifyRP XRT+. Over the past year or so, Agdia has commercialized another five AmplifyRP test kits in addition to the previously released six AmplifyRP kits. The newly released AmplifyRP kits include AmplifyRP XRT+ for Xylella fastidiosa (XF), AmplifyRP XRT for Clavibacter michiganensis subsp. Michiganensis (CMM), AmplifyRP Acceler8 for Grapevine red blotch virus (GRBV), AmplifyRP Acceler8 for Banana bunchy top virus (BBTV), and AmplifyRP Acceler8 for Tomato chlorotic dwarf viroid (TCDVd). All these AmplifyRP test kits are rapid, simple, as sensitive as PCR, and field-deployable. This rapid diagnostic AmplifyRP technology has been approved to be very useful for rapid diagnostic detection of all sorts of plant pathogens and will continue to help to greatly improve crop production and agriculture.

University of California-Davis/Foundation Plant Services, Davis, CA (Maher Al Rwahnih and Deborah Golino)

Accomplishments

At Foundation Plant Services (FPS), we continue to make advances in developing and refining our methods using high throughput sequencing (HTS) as a superior diagnostic tool. We have used sequence information generated by HTS analysis to design new, specific PCR primers for use in PCR diagnostics. In addition, HTS proves to be an invaluable tool in the discovery of unknown viruses and in establishing a baseline analysis of the virome of a crop.

Our research on Grapevine Pinot gris virus (GPGV), first reported in the US in 2015 in a study of the collections at FPS in Davis, California and subsequently in Napa Valley vineyards in 2016, continues to be focused on gaining a better understanding of the virus with a focus on the incidence and distribution in California vineyards, symptomology, optimized detection methods, and horizontal spread. To assess the prevalence of asymptomatic infections, we conducted multiple surveys from different grape growing regions in California. Our field survey was focused primarily in Napa and Sonoma Counties. In Napa County, 275 vines were tested from 14 vineyards growing multiple grape varieties. The percentage of vines sampled that tested positive for GPGV per infected location ranged from 8.7 to 100%. In Sonoma County, no vines tested positive for GPGV of 144 vines from 16 vineyards. In addition, no vines tested positive for GPGV of 236 samples tested from 30 vineyards in multiple grape growing counties in California. While GPGV is known to be asymptomatic, in other cases, it occurs as a mixed infection with other symptomatic viruses. When symptoms are present, they appear as typical GFLV symptoms which include chlorotic mottling, leaf deformation and stunting. A real-time PCR (qPCR/RT-qPCR) analysis of known grapevine viruses on 121 GPGV-positive samples revealed that all symptomatic vines were also infected with GFLV. To characterize viral strains and determine the phylogenetic relationships among symptomatic and asymptomatic isolates, phylogenetic analysis on the genome sequences demonstrated that California isolates share 95-99% homology with asymptomatic reference isolates and 98-100% homology with each other. Our preliminary analysis also demonstrated that the asymptomatic Californian isolates have similar movement protein stop codon polymorphism to Italian isolates. A complete molecular characterization of California isolates enabled us to ascertain if our current detection methods are adequate in capturing all isolates of GPGV. We evaluated multiple sets of primers for their ability to detect GPGV and found that these primers can give false negative results, missing some known positive vines, especially late in the season. To overcome this problem, we developed a new RT-qPCR (real-time) assay for the detection of GPGV using an alignment of all available GPGV isolates. As new isolates of GPGV are sequenced this assay will be consistently updated to ensure that it detects all variant strains of the virus. In addition to developing new assays, we have begun to evaluate the optimal time of year for sampling/testing and the type of tissue which should be used (petioles vs bark scrapings). Thus far, it appears that the virus is a “spring virus” as virus titer is higher in May/June compared to later in the season. In addition, we are monitoring GPGV spread in a subset of 430 vines of Merlot 3 on Teleki 5C rootstock within an 18-acre block immediately adjacent to other GPGV infected blocks in Napa County. In 2016, 47 plants were positive; this data set will be compared with the data from the next three years.

Progress has also been made in epidemiological studies of Grapevine leafroll-associated virus 3 (GLRaV-3). Five GLRaV-3 epidemics were analyzed utilizing a standardized approach to robustly characterize the temporal and spatial parameters. Published data included in the analysis are from Spain, New Zealand, and Napa Valley, CA together with new data from a historic vineyard in Napa Valley, CA. Linear regression analyses of logit-transformed incidence data indicated a maximum average increase of 11% per year in disease incidence, with considerable variation among locations. Spatial analyses, including distribution fitting, examination of the effective sample size, and evaluation of the parameters of the binary power law fitted to variance data for disease incidence, indicated a high degree of consistency among the data sets. In all cases, except at very low disease incidence, a high degree of spatial aggregation was noted, with evidence that the degree of aggregation varied as a function of mean disease incidence. The polyetic dynamics of disease follow a logistic-like pattern over multiple seasons, consistent with limitation by inoculum availability (infected vines) at low incidence and limitation by non-infected vines at high incidence.

New viral discoveries were made in pistachio trees. Pistachio trees from the National Clonal Germplasm Repository (NCGR) and selected orchards in California were surveyed for viruses and virus-like agents by high-throughput sequencing. Analyses of 60 trees, Pistacia vera and clonal UCB-1 hybrid rootstock (P. atlantica × P. integerrima), identified a novel virus found in the NCGR that showed low amino acid sequence homology (~42%) to members of genus Ampelovirus, family Closteroviridae and was provisionally named “Pistachio Ampelovirus A” (PAVA). A putative viroid, also found in the NCGR, showed similarities up to 87% to Citrus bark cracking viroid (CBCVd, genus Cocadviroid, family Pospiviroidae) and was provisionally named “Pistachio Cocadviroid 1” (PisCVd1). Both pathogens were graft transmissible to healthy UCB-1 plants. A field survey of 123 trees from commercial orchards found no incidence of PAVA, but five (4%) samples were infected with PisCVd1. Of the 690 NCGR trees, 16 (2.3%) were positive for PAVA and 172 (24.9%) were positive for PisCVd1. Additionally, several contigs across multiple samples exhibited significant sequence similarity to species in the families Caulimoviridae, Bromoviridae, Virgaviridae, Tombusviridae, Partitiviridae, Potyviridae, Alphaflexiviridae, Betaflexiviridae, Genomoviridae, Ophioviridae, and Phenuiviridae, and the genera Ourmiavirus and Sobemovirus. Results of the study establish the natural occurrence of a broad viral population infecting pistachio trees.

While HTS remains a powerful new technology with significant benefits, there are technical challenges associated with the technology that warrants the establishment of guidelines for its use in plant certification and quarantine programs. We have begun efforts in a collaborative project to coordinate the development of minimum basic requirements for the adoption of HTS technologies, including nucleic acid extractions, library preparation, depth of sequencing and bioinformatics, for the detection of viral pathogens.

Cornell University (Marc Fuchs)

Accomplishments

Research efforts focused on grapevine red blotch virus (GRBV), grapevine fanleaf virus (GFLV), grapevine virus E (GVE), Australian grapevine viroid (AGVd), and Agrobacterium vitis.

For grapevine red blotch virus (GRBV) from the genus Grablovirus in the family Geminiviridae (Cieniewicz et al., 2017a; Varsani et al., 2017), we monitored GRBV spread over a three-year period (2014–2016) in a 2-hectare Vitis vinifera cv. ‘Cabernet franc’ vineyard based on an initially low disease incidence and an aggregation of symptomatic vines at the edge of the vineyard proximal to a wooded riparian area. The incidence of diseased plants increased by 1-2% annually (Cieniewicz et al., 2017b). Spatial analysis of diseased plants in each year using ordinary runs analysis within rows and Spatial Analysis by Distance IndicEs (SADIE) demonstrated aggregation. Spatiotemporal analysis between consecutive years within the association function of SADIE revealed a strong overall association among all three years (X= 0.874–0.945). Analysis of epidemic spread fitting a stochastic spatiotemporal model using the Monte Carlo Markov Chain method identified strong evidence for localized (within vineyard) spread. A spatial pattern consisting of a combination of strongly aggregated and randomly isolated symptomatic vines within 8-years post-planting suggested unique epidemic attributes compared to those of other grapevine viruses vectored by mealybugs and soft scales or by dagger nematodes for which typical within-row spread and small-scale autocorrelation are well documented. These findings are consistent with the existence of a new type of vector for a grapevine virus (Cieniewicz et al., 2017b). To determine the diversity and distribution of potential vector candidates in an infected vineyard, sticky cards were placed in 2015-2016 in a ‘Cabernet franc’ study site where disease incidence increased by nearly 20% between 2014 and 2016. Insects on sticky card traps were identified to species when possible by morphological characteristics and by sequencing of the mitochondrial cytochrome C oxidase subunit 1 gene. Subsets of insect species/taxa were removed from sticky cards and tested for the presence of GRBV by multiplex polymerase chain reaction. GRBV was consistently detected in Spissistilus festinus (Membracidae), Colladonus reductus (Cicadellidae), Osbornellus borealis (Cicadellidae) and a Melanoliarus species (Cixiidae) (Cieniewicz et al., 2017c). Populations of these four candidate vectors peaked from June to September with viruliferous S. festinus culminating from late June to early July in both years. An assessment of co-occurrence and co-variation between GRBV-infected vines and viruliferous insects using the association function of SADIE identified a significant association between the spatial distribution of infected vines and viruliferous S. festinus. Collectively, the findings revealed the epidemiological significance of S. festinus as a vector of GRBV and the need for testing the transmission capability of C. reductus, O. borealis, and the Melanoliarus species (Cieniewicz et al., 2017c). They also stress the relevance of the greenhouse studies previously carried out by Bahder et al. (2016) on the vectoring ability of S. festinus.

We described the presence of GRBV in free-living grapes, including V. californica x V. vinifera, proximal to diseased vineyards (Perry et al., 2016). The full-length GRBV genome sequence was more similar among isolates from free-living grapes and a Merlot isolate than to more proximal Cabernet franc isolates. These results suggested that GRBV can spread by natural means (Perry et al., 2016). Subsequently, Badher et al. (2016) reported on S. festinus as a vector of GRBV. In addition to GRBV in wild grapes, we described a new grablovirus, name wild Vitis virus 1 (WVV1), in free-living grapes in California (Perry et al., 2017). The complete genome of WVV1 ranges from 3,204 to 3,278 nucleotides in size. The genome most closely resembles that of GRBV in both its organization and sequence identity (57-59%) (Perry et al., 2017). No information is available yet on the biology of WVV1 and its host range.

In collaboration with Agdia, Inc., we contributed to the development of an AmplifyRP Acceeler8 diagnostic assay for GRBV (Li et al., 2017). This assay is rapid, reliable, specific and sensitive, and adapted to crude sap or nucleic acid extracts. It specifically detects up to 11 copies of GRBaV genomic DNA in a matrix of healthy crude extract. The AmplifyRP Acceeler8 diagnostic assay may assist the timely removal of GRBV-infected vines in vineyards.

We also determined the economic cost of GRBV in California, Washington State and New York State. The economic impact was estimated to range from $2,213/ha in eastern Washington, when disease onset occurs at a low initial infection level and there is a low price penalty for poor fruit quality, to $68,548/ha in Napa County, when initial infection rates and quality penalties are both high (Ricketts et al., 2017). These values were further used to develop profit-maximizing disease management options. Roguing symptomatic vines and replanting with clean vines derived from virus-tested stocks minimize losses if GRBV incidence is low to moderate (below 30%), while a full vineyard replacement should be pursued if disease incidence is higher, generally above 30%. These findings should help vineyard managers adopt optimal GRBV management strategies (Ricketts et al., 2017).

For grapevine fanleaf virus (GFLV) from the genus Nepovirus in the family Secoviridae (Thompson et al., 2017), we addressed a fundamental question in terms of virus-host interactions for symptom expression. By using infectious clones of GFLV strains F13 and GHu in a reverse genetics approach with wild-type, assortant and chimeric viruses, the molecular determinant of necrotic lesions caused by GFLV-F13 on inoculated leaves of Nicotiana occidentalis was mapped to the RNA2-encoded protein 2AHP, particularly to its 50 C-terminal amino acids (Martin et al., 2017). The necrotic response showed hallmark characteristics of a genuine hypersensitive reaction, such as the accumulation of phytoalexins, reactive oxygen species, pathogenesis-related protein 1c and hypersensitivity-related (hsr) 203J transcripts. Transient expression of the GFLV-F13 protein 2AHP fused to an enhanced green fluorescent protein (EGFP) tag in N. occidentalis by agroinfiltration was sufficient to elicit a hypersensitive reaction. In addition, the GFLV-F13 avirulence factor, when introduced in GFLV-GHu, which causes a compatible reaction on N. occidentalis, elicited necrosis and partially restricted the virus. This is the first identification of a nepovirus avirulence factor that is responsible for a hypersensitive reaction in both the context of virus infection and transient expression (Martin et al., 2017).

For grapevine virus E (GVE) from the genus Vitivirus in the family Betaflexiviridae, we analyzed the genetic variability of isolates from California and New York. All GVE isolates were found in mixed infection with closterovirids or vitiviruses (Vargas et al., 2016). Sequence information indicated more than 98% nucleotide identity in the 3’ terminus of the coat protein gene, a short intergenic regions and the 5’ terminus of the putative nucleic acid binding protein gene of several GVE isolates. These results confirmed the presence of GVE in major U.S. grape-growing regions and indicated a very low level of genetic diversity (Vargas et al., 2016).

For Australian grapevine viroid (AGVd) from the genus Apscaviroid in the family Pospiviridae, we reported its detection in two vineyards of V. vinifera cv. Syrah in New York. Vines were sampled in 2014, nucleic acid extracts prepared, and Illumina-compatible small RNA libraries constructed, sequenced (Illumina Hiseq 4000; single-end 50 nt reads), and analyzed (Vargas-Ascencio et al., 2017). AGVd was detected in the Syrah vines and its complete genome sequence showed >99% nucleotide identity to that of the original variant described by Rezaian and colleagues. To confirm this initial detection, vines were resampled in 2016 and an RT-PCR amplicon of approximately 270 nucleotides in length was produced; the product was detected in three of five vines and sequenced by the dideoxy DNA sequencing method. This second variant also showed >99% nucleotide sequence identity to the original variant. This study unequivocally confirms the presence of AGVd in North American vineyards (Vargas-Ascencio et al., 2017).

For Agrobacterium vitis, we showed that the bacterium can be detected in dormant grape buds as well as on surfaces of leaves collected from commercial vineyards using a highly selective and sensitive method based on magnetic capture hybridization together with real-time PCR (Canik-Orel et al., 2017). Highest percentages of detection occurred in samples collected from vineyards with high incidences of crown gall. The bacterium was also detected in 22% of wild grapevines (Vitis riparia) collected in New York and from 25% of feral grapevines that included V. californica in California. Several of the free-living vines sampled were growing more than 2km from commercial vineyards, demonstrating that wild grapevines can serve as a significant reservoir of inoculum (Canik-Orel et al., 2017).  

Washington State University (Naidu Rayapati)

Virus diseases affecting fruit quality and vine health are one the highest research priorities for the grape and wine industry in Washington State. In response, the grape virology program (http://wine.wsu.edu/virology/ ) is conducting fundamental and applied research to generate science-based knowledge for mitigating negative impacts of virus diseases in vineyards. Among the major viral diseases, grapevine leafroll continues to be a major constraint to vineyard sustainability compared to grapevine red blotch and fanleaf degeneration and decline. Virus indexing of grapevine samples revealed that Grapevine leafroll-associated virus 3 is ubiquitous in grower vineyards. Molecular characterization of the genome of Grapevine leafroll-associated virus 1 revealed several unique features of the virus compared to other closteroviruses. Studies in commercial vineyards have shown that leafroll, red blotch, and fanleaf degeneration and decline can cause significant reduction in fruit yield and quality. However, these negative impacts were found to be cultivar- and site-specific responses likely influenced by genotype-by-environment interactions. Using baiting assays, the spread of Tobacco ring spot virus (TRSV) was demonstrated from infected grapevines to healthy cucumbers and Cabernet Franc vines. TRSV was detected by RT-PCR only in dagger nematodes isolated from soil samples taken near symptomatic grapevines. Using morphological characteristics and sequence analysis of the 28S large ribosomal D2-D3 expansion segment and the internal transcribed spacer region, the dagger nematode present in the vineyard soil was identified as Xiphinema rivesi. Virus indexing of grapevine samples done so far revealed the absence of Grapevine red blotch virus in certified grapevine mother blocks in Washington State. Participatory approaches were pursued with grape growers to conduct applied research activities in vineyards. The research-based knowledge was shared with grape and wine industry stakeholders via presentations at meetings and workshops and through publications in popular magazines, such as the Good Fruit Grower, for broader dissemination of research outcomes.

Clemson University, SC (S.W. Scott)

In the summer/fall of 2011 the root suckers of a tree of Prunus serrulata cv Shirofugen grafted onto virus-indexed F12/1 Mazzard growing at the university research farm (Musser Farm) displayed distinct line patterns. Full length genomic sequence for the virus was developed and deposited as accession KX389311 in GenBank. This accession showed 97% identity with accession KF356396 (an isolate of Cherry rusty mottle-associated virus described from Washington State). This virus had not previously been described from South Carolina (SC). It is suggested that the virus originated from ornamental flowering cherry material (‘Yoshino’ cherry [Prunus × yedoensis]) planted on the nearby University Campus and “chip-budded” to the tree of “Shirofugen” as a positive control sample during a bioassay for Prunus necrotic ringspot virus. RT-PCR tests of leaves from both the suckers and the scion detected the virus in the suckers but not in the scion. A survey of 15 other Yoshino cherry trees growing on campus using both PCR, and symptom expression on Mazzard seedlings following graft transmission, detected the presence of the same virus in 4 of the trees sampled.

The incidence of 5 viruses frequently found affecting blackberry was examined between 2012- 2014 in 2 “large” plantings in SC by employing sentinel plants. Virus-indexed sentinel plants of Ouachita and Natchez were exposed at a number of different locations in 2 plantings: 35 acres at Cooley’s in Boiling Springs, SC and 29 acres at the Double-J farm in Landrum SC. The exposure was for 30 days in each of the months of May through August. Following exposure the plants were treated with insecticides and then maintained in a screen-house until the following spring when RT-PCR testing of the new growth was completed. The 5 viruses for which tests were completed were Blackberry yellow vein-associated virus (BYVaV), Blackberry chlorotic ringspot virus (BCRV), Blackberry virus Y (BVY), Blackberry virus E (BVE), and Blackberry leaf mottle associated virus (BLMaV). Although the 2 locations were only 30 miles apart, and had blackberry cultivars in common (Natchez), the incidence of viruses detected was different. For example in 2012 a peak of BYVaV (11/100 sentinel plants) was detected in July at Cooley’s whereas in 2013 a peak of BYVaV (19/60 sentinel plants) was detected in May at the Double-J farm and only 4 detections of BYVaV we made for the entire season at Cooley’s. All of the viruses have insect vectors. Although BCRV is thought to be transmitted through the action of thrips feeding on wind-blown infected pollen grains rather than direct acquisition and inoculation of the virus through insect feeding.

PA Department of Agriculture, Harrisburg, PA (Katya Nikolaeva)

The PA Department of Agriculture continues to operate the Fruit Tree Improvement Program (FTIP), a specialized virus-tested fruit tree certification program. Three nurseries have been participating in the FTIP this year. The purpose of the program is to encourage the use of NCPN-produced or best-available source material in nursery stock production. The program involves working with nurseries to design practices consistent with clean-stock certification regulations; auditing nursery practices; and inspecting and testing nursery source and production materials.

In spring 2017, over 2,000 samples were tested for viruses of concern. All stone fruit nursery materials were tested for Prunus necrotic ringspot, prune dwarf, tomato ringspot, and plum pox virus. Sampling in apple and pear was primarily for tomato ringspot virus. All blocks met virus-testing requirements for FTIP certification. No PDV or ToRSV was detected in rootstock blocks or in registered source blocks. PNRSV remains the most commonly found viruses in Prunus in Pennsylvania, although finds in registered blocks and nursery production blocks are rare. All samples tested negative for plum pox virus, a virus declared eradicated from Pennsylvania in 2009.

In cooperation with Dr. Kari Peter, Penn State University, a Farm Bill-funded survey for exotic diseases in orchards was conducted targeting plum pox virus, two exotic phytoplasmas, and two exotic brown rot pathogens. No exotic targets were detected, but we did confirm presence of Ca. Phytoplasma pruni (16SrIII-A group, X-disease group) in apple and Ca. Phytoplasma pyri (16SrX, Apple Proliferation group) in pears for a third year. Potentially new phytoplasma species related to ash yellows group was detected in peaches for a second year.

Data gathering continued on a Rapid Apple Decline syndrome in 3-4-year-old apple trees on M9 rootstocks. In collaboration with Ruhui Li (USDA ARS) and Kari Peter (Penn State) we discovered a new luteovirus from apple trees in the RAD-affected orchards using high throughput sequencing (HTS) technology. The virus is provisionally named Apple luteovirus 1 (ALV-1). Currently we are conducting a survey of RAD affected orchards in PA for a presence of new luteovirus and known latent viruses to determine their possible contribution to RAD symptoms.

Micropropagation and Repository Unit (MPRU), North Carolina State University (Christie Almeyda)

The MPRU maintains G1 pathogen-tested (Foundation) in the Repository of Strawberry cultivars and advanced selections (greenhouse and in vitro), blackberry cultivars (greenhouse, screen house and cold storage), raspberry cultivars and advanced selections (greenhouse, screen house and cold storage) and blueberry cultivars and advanced selections (greenhouse, screen house and in vitro). Currently, material that is in various stages of treatment corresponds to 2 blueberry, 2 strawberry, and 7 blackberry advanced selections. P526 permits were obtained and will be used to exchange positive controls with other centers in the NCPN. Virus testing capacity and standardization has improved to follow NCPN standards. Positive controls are being obtained from other centers and commercial sources. Current activities are the ring test with other NCPN centers, yearly testing of strawberry mother plants, clean-up of 2015 and 2016 blackberry selections from Dr. Clark in Arkansas, blueberry selections from Dr. Ballington in North Carolina and raspberry selections from Dr. Fernandez in North Carolina. All this material has to be virus tested and meristem-tip culture or established in tissue culture by tip/nodal cuttings.

MPRU leadership changes

Dr. Christie Almeyda was appointed as interim director by the Head of the Department of Entomology and Plant Pathology in June 2017.

CFIA, Center for Plant Health, Government of Canada

James D. 2017. Perspectives on strategies for controlling the spread of plum pox virus, causal agent of sharka/plum pox disease. Acta Hortic 1163. ISHS 2017 Proceedings of the III International Symposium on Plum Pox Virus; p.129-136.

James D, Phelan J. 2017. Complete genome sequence and analysis of blackcurrant leaf chlorosis associated virus, a new member of the genus Idaeovirus. Archives of Virology. 162: 1705-1709.

James D, Sanderson D, Dolgikh S, Spiegel S. 2017. Molecular analysis of the complete genomes of apricot and plum isolates of Plum pox virus detected in a Prunus germplasm collection in Almaty’s Pomological Gardens, Kazakhstan. Acta Hortic. 1163. ISHS 2017 Proceedings of the III International Symposium on Plum Pox Virus; p. 101-107.

Kesanakurti, P., Belton, M., Saeed, H., Rast, H., Boyes, I., and Rott, M. 2016. Screening for plant viruses by next generation sequencing using a modified double strand RNA extraction protocol with an internal amplification control. Journal of Virological Methods. 236: 35-40

Phelan J, James D. 2016. Complete genome sequences of a putative new alphapartitivirus detected in Rosa spp. Archives of Virology. 161: 2623-2626.

Poojari S, Boulé J, DeLury N, Lowery D.T., Rott M, Schmidt A-M, Urbez-Torres J.T. 2017. Epidemiology and genetic diversity of grapevine leafroll-associated viruses in British Columbia. Plant Disease.

Poojari S, Lowery D.T., Rott M, Schmidt A-M, Urbez-Torres J.T. 2017. Incidence, distribution and genetic diversity of Grapevine red blotch virus in British Columbia. Canadian Journal of Plant Pathology 39:2 201-211.

Rott et al. 2017. Application of Next Generation Sequencing for Diagnostic Testing of Tree Fruit Viruses and Viroids. Plant Disease 101:8, 1489-1499.

Safarova D, Neoralova V, James D, Navratil M. 2017. Almond (Prunus dulcis L.) - not a natural host of Plum pox virus in the Czech Republic. Acta Hortic 1163. ISHS 2017 Proceedings of the III International Symposium on Plum Pox Virus; 123-127.

Sanderson D, Fu J, James D. 2017. Identification of possible evolutionary pathways of Plum pox virus and predicting amino acid residues of importance to host adaptation. Acta Hortic. 1163. ISHS 2017 Proceedings of the III International Symposium on Plum Pox Virus; p. 107-116.

James D, Phelan J, Jesperson G. 2017. The Geneva Complex – an interesting disease perspective based on the results of NGS analysis. 24^th International Conference on Virus and Other Graft Transmissible Diseases of Fruit Crops (ICVF), Thessaloniki, Greece, June 5 – 9, 2017. Book of Abstracts. Pg 43 (Abstr.)

James D, Phelan J, Sanderson D. 2017. Evidence of circular RNA associated with blackcurrant leaf chlorosis associated virus. 24^th International Conference on Virus and Other Graft Transmissible Diseases of Fruit Crops (ICVF), Thessaloniki, Greece, June 5 – 9, 2017. Book of Abstracts. Pg 126 (Abstr.)

Jelkmann W, Sanderson D, Berwarth C, James D. 2017. Detection and characterization of the complete genome of the first cherry (C) strain isolate of plum pox virus detected in Germany in sour cherry (Prunus cerasus). 24^th International Conference on Virus and Other Graft Transmissible Diseases of Fruit Crops (ICVF), Thessaloniki, Greece, June 5 – 9, 2017. Book of Abstracts. Pg 99 (Abstr.)

Messmer A, Sanderson D, Braun G, Serra P, Flores R, James D. 2017. Characterization of a new and distinct population of hammerhead viroid-like RNA detected by next-generation sequencing using total RNA from apple (Malus domestica) cv. Pacific Gala. 24^th International Conference on Virus and Other Graft Transmissible Diseases of Fruit Crops (ICVF), Thessaloniki, Greece, June 5 – 9, 2017. Book of Abstracts. Pg 36 (Abstr.)

Milusheva S, Phelan J, Piperkova N, Nikolova V, James D. 2017. Detection and molecular characterization of an unusual virus in cherry. 24^th International Conference on Virus and Other Graft Transmissible Diseases of Fruit Crops (ICVF), Thessaloniki, Greece, June 5 – 9, 2017. Book of Abstracts. Pg 122 (Abstr.)

USDA-ARS, Horticultural Crops Research Unit, Corvallis, OR

Diaz-Lara, A. and Martin, R.R. 2016. Blueberry fruit drop associated virus: A new member of the family Caulimoviridae isolated from blueberry exhibiting fruit drop symptoms. Plant Dis. 100:2211-2214.

Hassan, M., Di Bello, P.L., Keller, K.E., Martin, R.R., Sabanadzovic, S. and Tzanetakis, I.E. 2017. A new, widespread emaravirus discovered in blackberry. Virus Research 235:1-5.

Martin, R.R. and Ellis, P. 2017. In memoriam/A la memoire de, Dr. Richard Stace-Smith, 1924-2017. Canadian Journal Plant Pathology 39:1-4.

Tzanetakis, I.E. and Martin, R.R. 2017. A systems-based approach to manage strawberry virus diseases. Canadian Journal Plant Pathology 39:5-10.

Diaz-Lara, A., Santamaria, L. and Martin, R.R. 2017. Identification of Tomato mosaic virus (ToMV) and Potato latent virus (PotLV) as mixed infection in Chinese lantern (Physalis alkekengi) in the United States. Plant Dis. 101:1061.

University of Arkansas

Hassan, M., Di Bello. P.L., Keller, K.E., Martin, R.R., Sabanadzovic S. and Tzanetakis, I.E. 2017. A new, widespread emaravirus discovered in blackberry. Virus Research 235: 1-5.

Tzanetakis, I.E. and Martin, R.R. 2017. A systems-based approach to counter strawberry virus diseases. Canadian Journal of Plant Pathology 39: 5-10.

Thekke-Veetil, T., Khadgi, A., Johnson, D.T., Burrack, H., Sabanadzovic, S. and Tzanetakis, I.E. 2017. First report of raspberry leaf mottle virus in blackberry in the United States. Plant Disease 101: 265

Shahid, M.S., Aboughanem-Sabanadzovic, N., Sabanadzovic, S. and Tzanetakis, I.E. 2017. Genomic characterization and population structure of a badnavirus infecting blackberry. Plant Disease 101: 110-115

Martin R.R. and Tzanetakis, I.E. 2017. Introduction to diseases caused by viruses and virus-like agents. Pp. 70-71. In: Martin, R.R., Ellis, M.A., Williamson, B. and Williams, R.N. (Ed) Compendium of Raspberry and Blackberry Diseases and Insects 2nd Edition. APS Press, St. Paul, MN.

Tzanetakis, I.E., Susaimuthu, J., Sabanadzovic S., and Martin R.R. 2017. Blackberry Yellow Vein Disease Complex (BYVD). Pp. 71-75. In: Martin, R.R., Ellis, M.A., Williamson, B. and Williams, R.N. (Ed) Compendium of Raspberry and Blackberry Diseases and Insects 2nd Edition. APS Press, St. Paul, MN.

MacFarlane, S.A., Tzanetakis, I.E., Halgren, A.B. and Martin, R.R. 2017. Raspberry mosaic disease complex. Pp. 75-78. In: Martin, R.R., Ellis, M.A., Williamson, B. and Williams, R.N. (Ed.) Compendium of Raspberry and Blackberry Diseases and Insects 2nd Edition. APS Press, St. Paul, MN.

Tzanetakis, I.E. 2017. Blackberry virus F. Pp. 80. In: Martin, R.R., Ellis, M.A., Williamson, B. and Williams, R.N. (Ed.) Compendium of Raspberry and Blackberry Diseases and Insects 2nd Edition. APS Press, St. Paul, MN.

Quito-Avila, D.F., Tzanetakis, I.E. and Martin, R.R. 2017. Raspberry latent virus. Pp. 84-85. In: Martin, R.R., Ellis, M.A., Williamson, B. and Williams, R.N. (Ed) Compendium of Raspberry and Blackberry Diseases and Insects 2nd Edition. APS Press, St. Paul, MN.

Tzanetakis, I.E. and Martin, R.R. 2017. Strawberry necrotic shock virus. Pp. 90-91. In: Martin, R.R., Ellis, M.A., Williamson, B. and Williams, R.N. (Ed) Compendium of Raspberry and Blackberry Diseases and Insects 2nd Edition. APS Press, St. Paul, MN.

Martin, R.R. and Tzanetakis, I.E. 2017. Other viruses and virus-like agents. In: Pp. 91-93. In: Martin, R.R., Ellis, M.A., Williamson, B. and Williams, R.N. (Ed) Compendium of Raspberry and Blackberry Diseases and Insects 2nd Edition. APS Press, St. Paul, MN.

Tzanetakis, I.E. and Martin, R.R. 2016. Blueberry latent spherical virus. Pp. 60, In: Polashock, J.J., Caruso, F.L., Averill, A.L. and Schilder A.C. (Ed) Compendium of Blueberry, Cranberry and Lingonberry Diseases and Pests 2nd Edition, APS Press, St. Paul, MN.

Tzanetakis, I.E. and Martin, R.R. 2016. Blueberry latent virus. Pp. 60, In: Polashock, J.J., Caruso, F.L., Averill, A.L. and Schilder A.C. (Ed) Compendium of Blueberry, Cranberry and Lingonberry Diseases and Pests 2nd Edition, APS Press, St. Paul, MN.

Tzanetakis, I.E. and Martin, R.R. 2016. Blueberry virus A. Pp. 60-61, In: Polashock, J.J., Caruso, F.L., Averill, A.L. and Schilder A.C. (Ed) Compendium of Blueberry, Cranberry and Lingonberry Diseases and Pests 2nd Edition, APS Press, St. Paul, MN.

Martin, R.R. and Tzanetakis, I.E. 2016. Blueberry mosaic virus. Pp. 64, In: Polashock, J.J., Caruso, F.L., Averill, A.L. and Schilder A.C. (Ed) Compendium of Blueberry, Cranberry and Lingonberry Diseases and Pests 2nd Edition, APS Press, St. Paul, MN.

Tzanetakis, I.E. and Martin, R.R. 2016. Blueberry Certification. Pp. 154-156, In: Polashock, J.J., Caruso, F.L., Averill, A.L. and Schilder A.C. (Ed) Compendium of Blueberry, Cranberry and Lingonberry Diseases and Pests 2nd Edition, APS Press, St. Paul, MN.

University of Hawaii

Green, J.C., Borth, W.B., Melzer, M.J., Wang, Y.N., Hamim, I.,and Hu, J.S. 2017. First Report of Bean common mosaic virus infecting Phaseolus lunatus in Hawaii. Plant Disease 101:1557.

Green, J.C. and Hu. J.S. 2017. Editing Plants for Virus Resistance Using CRISPR-Cas. Acta Virologica 61: 138 – 142.

Li, Y., Wang, Y., Hu, J., Xiao, L., Tan, G., Lan, P., Liu, Y., and Li, F. 2017. Molecular and biological characteristics of Tomato mottle mosaic virus Chinese isolate. Virology Journal 14:15-23.

Dey, K., Melzer M., and J. Hu 2017. Virus-Induced Gene Silencing in Plant Biotechnology, Volume 2: Transgenics, Stress Management, and Biosafety Issues. (In press)

James C. Green, Wayne Borth, John S. Hu (2016) Engineering Resistance to Viruses. In: Mohandas S, Ravishankar KV (eds) Banana: genomics and transgenic approaches for genetic improvement. Springer, Singapore, pp 237-246.

Wang, Y. N., Borth, W. B., Hamim, I., Green, J.I., Melzer, M.J., and Hu, J.S. 2017. First Report of Taro bacilliform CH Virus (TaBCHV) on Taro (Colocasia esculenta) in Hawaii. Plant Disease 101:1334.

Wang, Y.N., Melzer, M., Borth, W., Green, J. Hamim, I., and Hu, J.S. 2017. First report of Bean yellow mosaic virus in vanilla in Hawaii. Plant Disease 101:1557.

Zhang, J., Borth, W.B., Sether, D., Wang, I., Lin, B, Melzer, M.J., Shen, H., Pu, X, Nelson, S., Hu, J.S. 2017. Characterization of Canna yellow mottle virus in a new host, Alpinia purpurata, in Hawaii. Phytopathology 107:791-799.

Watanabe, S., Ruschel, R., Marrero, G., Sether, D., Borth, W., Hu, J., and Melzer, M. 2016. A distinct lineage of Watermelon mosaic virus naturally infects honohono orchid (Dendrobium anosmum) and passionfruit (Passiflora edulis) in Hawaii. New Disease Reports 34:13.

Green, K.J., Chikh-Ali, M., Hamasaki, R, Melzer, M.J., and Karasev, A.V. 201X. Potato virus Y (PVY) isolates from Physalis peruviana are unable to systemically infect potato or pepper and form a distinct new lineage within the PVY^C strain group. Phytopathology. (In press)

Dey, K., Melzer, M., Sun, X., and Adkins, S. 201X. Tomato chlorotic spot virus identified in Marsdenia floribunda in Florida. Plant Health Progress. (In press)

Agdia Inc.

Hammond RW, Zhang S. 2016. Development of a rapid diagnostic assay for the detection of Tomato chlorotic dwarf viroid based on isothermal reverse-transcription-recombinase polymerase amplification. Journal of Virological Methods 236:62-67.

Zhang S, Russell P, McOwen N, Davenport B, Li R. 2017. Development of a novel isothermal AmplifyRP® assay for rapid detection of Plum pox virus - a real-time and endpoint assay in a single PCR tube. Acta Hortic. (ISHS) 1163:31-37.

Li R, Fuchs MF, Perry KL, Mekuria T, Zhang S. 2017. Development of a fast diagnostic AmplifyRP Acceler8 assay for Grapevine red blotch virus. J. Plant Pathol. (accepted).

University of California-Davis/Foundation Plant Services, Davis, CA

Al Rwahnih, M., Alabi, O.J., Westrick, N.M., Golino, D. and Rowhani, A. 2017. Description of a novel monopartite geminivirus and its defective subviral sequence in grapevine (Vitis vinifera L.). Phytopathology, 107(2): 240-251.

Yahaya, A., Al Rwahnih, M., Dangora, D., Gregg, L., Alegbejo, M., Kumar, P., and Alabi, O. 2017. First report of Maize yellow mosaic virus infecting sugarcane (Saccharum spp.) and itch grass (Rottboellia cochinensis) in Nigeria. Plant Disease/ http://dx.doi.org/10.1094/PDIS-03-17-0315- PDNA.

Olufemi J. Alabi, Al Rwahnih. M., Jifon, J. L., Sétamou, M., Brown, J.K., Gregg, L., and J-W. Park. 2017. A Mixed Infection of Lettuce chlorosis virus, Papaya ringspot virus, and Tomato yellow leaf curl virus-IL Detected in a Texas Papaya Orchard Affected by a Virus-Like Disease Outbreak. Plant Disease/ http://dx.doi.org/10.1094/PDIS-01-17-0118-RE.

Voncina, D., Al Rwahnih, M., Rowhani, A., Gouran, M. and Almeida, R. 2017. Viral Diversity in Autochthonous Croatian Grapevine Cultivar. Plant Disease, PDIS-10-16-1543-RE.

Al Rwahnih, M., Alabi, O.J., Westrick, N.M., Golino, D. and Rowhani, A. 2017. Near complete genome sequence of grapevine fabavirus, a novel putative member of the genus Fabavirus. Genome Announcements, 4(4): e00703-16.

Osman, F., Al Rwahnih, M. and Rowhani, A. 2017. Real-Time RT-qPCR Detection of Cherry Rasp Leaf Virus, Cherry Green Ring Mottle Virus, Cherry Necrotic Rusty Mottle Virus, Cherry Virus A and Apple Chlorotic Leaf Spot Virus in Stone Fruits. Journal of Plant Pathology, 99(1): 279-285.

Rasool, S., Naz, S., Rowhani, A., Golino, D.A., Westrick, N.M., Farrar, K.D., and Al Rwahnih, M. 2017. First report of Grapevine Pinot Gris virus infecting grapevine in Pakistan. Plant Disease/https://doi.org/10.1094/PDIS-04-17-0476-PDN.

Fagundes Silva, J.M., Al Rwahnih, M., Blawid, R., Nagata, T., and Fajardo, T. 2017. Discovery and molecular characterization of a novel anamovirus, Grapevine enamovirus-1. Virus genes. ** IN PRESS **

Arnold, K., Golino, D. A., and N. McRoberts. 2017. A synoptic analysis of the temporal and spatial aspects of grapevine leafroll disease in an historic Napa vineyard and experimental vine blocks. Phytopathology. 107:418 -426.

Rowhani, A., Daubert, S.D., Uyemoto, J.K. Al Rwahnih, M. and M. Fuchs. 2017. Grapevine Viruses: Molecular Biology, Diagnostics and Management, Chapter five. American Nepoviruses, 109-126.

Al Rwahnih, M., Rowhani, A., and P. Saldarelli. 2017. Grapevine Viruses: Molecular Biology, Diagnostics and Management, Chapter ten. Grapevine leafroll-associated virus-7., 221-228.

Rowhani, A., Uyemoto, J.K., Golino, D., Daubert, S.D., and M. Al Rwahnih. 2017. Grapevine Viruses: Molecular Biology, Diagnostics and Management, Chapter thirteen-backspace. Viruses Involved in Graft-Incompatibility and Decline, 289-302.

Rowhani, A., Osman, F., Daubert, S.D., Al Rwahnih, M. and P. Saldarelli. 2017. Grapevine Viruses: Molecular Biology, Diagnostics and Management, Chapter twenty. Chain Reaction Methods for the Detection of Grapevine Viruses and Viroids., 431-450.

Saldarelli, P., Giampetruzzi, A., Maree, H., and M. Al Rwahnih. 2017. Grapevine Viruses: Molecular Biology, Diagnostics and Management, Chapter thirty. Next generation sequencing: advantages beyond virus identification, 625-642.

Golino, D. A., Fuchs, M., Sim, S., Farrar, K., and G. P. Martelli. 2017. Grapevine Viruses: Molecular Biology, Diagnostics, and Management, Chapter twenty-seven. Improvement of grapevine planting stock through sanitary selection a pathogen elimination, 561-580.

Golino, D. A., Fuchs, M., Al Rwahnih, M., Farrar, K., Schmidt, A., and G.P. Martelli. 2017. Grapevine Viruses: Molecular Biology, Diagnostics and Management, Chapter twenty-eight. Regulatory aspects of grape viruses and virus diseases: certification, quarantine, and harmonization, 581-598.

Al Rwahnih, M., Westrick, N., Golino, D., and Rowhani, A. Survey for grapevine pinot gris virus infecting grapevine in the Foundation Plant Services Vineyards at the University of California, Davis. American Phytopathological Society. Tampa, FL, 2016.

Voncina, D., Al Rwahnih, M., Rowhani, A., and Almeida, R. 2016. Survey for viruses of grapevine (Vitis vinifera L.) in coastal vineyards of Croatia. American Phytopathological Society. Tampa, FL.

Alabi, O., Al Rwahnih, M., Brown, J., Jifon, J., Park, J., Gregg, L., Setamou, M., and Idris, A. 2016. Association of a mixed infection of Lettuce chlorosis virus, Papaya ringspot virus, and Tomato yellow leaf curl virus-IL in a Texas papaya orchard. American Phytopathological Society. Tampa, FL.

Al Rwahnih, M., Golino, D., Westrick, N., Stevens, K., Trouillas, F., Preece, J., Kallsen, C., Farrar, K., and Rowhani, A. Metagenomic analysis of virus and virus-like pathogens infecting pistachio in California. San Antonio. ** SUBMITTED **

Al Rwahnih, M., Golino, D., Westrick, N., Diaz Lara, A., Cooper, M., Smith, R., Battany, M., Bettiga, L., Zhuang, S., Arnold, A., Farrar, K., and Rowhani, A. Grapevine pinot gris virus: an emerging virus in Napa Valley vineyards. San Antonio, TX. ** SUBMITTED **

Diaz Lara, A., Stevens, K., Westrick, N., Golino, D., and Al Rwahnih, M. Identification of a caulimo-like virus in pistachio via high-throughput sequencing. San Antonio, TX. ** SUBMITTED **

Al Rwahnih, M., Klaassen, V., Stevens, K., Arnold, K., Maree, H.J., Westrick, N., and Golino, D. Molecular characterization of divergent Grapevine leafroll-assiciated virus 3 isolates in California, USA. San Antonio, TX. ** SUBMITTED **

Harvenson, R., Al Rwahnih, M., Tian, T., Karasev, A., and Gulya T. A New Virus Disease of Sunflower in Nebraska. San Antonio, TX. ** SUBMITTED **

Cornell University

Canik-Orel, D., Reid, C., Fuchs, M. and Burr, T. 2017. Environmental sources of Agrobacterium vitis in vineyards and wild grapevines. American Journal of Enology and Viticulture, 68:213-217.

Cieniewicz, E.J., Perry, K.L. and Fuchs, M. 2017a. Grapevine red blotch virus: Molecular biology of the virus and management of the disease. In: Grapevine Viruses: Molecular Biology, Diagnostics and Management. Meng, B.,

Martelli, G.P., Golino, D.A. and Fuchs, M.F (eds). Springer Verlag, pp. 303-314.

Cieniewicz, E., Pethybridge S., Gorny, A., Madden, L., Perry, K.L., McLane, H. and Fuchs, M. 2017b. Spatiotemporal spread of grapevine red blotch-associated virus in a California vineyard. Virus Research, DOI: 10.1016/J.VIRUSRES.2017.03.020.

Cieniewicz, E., Pethybridge S., Loeb, G., Perry, K.L., and Fuchs, M. 2017c. Diversity and spatial distribution of vector candidates of grapevine red blotch virus in a diseased vineyard. Phytopathology, in revision.

Fuchs, M. and Lemaire, O. 2017a. Novel approaches for virus disease management. In: Grapevine Viruses: Molecular Biology, Diagnostics and Management. Meng, B., Martelli, G.P., Golino, D.A. and Fuchs, M.F (eds). Springer Verlag, pp. 599-621.

Fuchs, M. Schmitt-Keichinger, C. and Sanfaçon, H. 2017b. A renaissance in nepovirus research provides new insights into their molecular interface with hosts and vectors. In: Advances in Virus Research, M. Kielian, K. Maramorosch, T.C Mettenleiter and M.J Roosinck (eds.), pp. 61-105.

Golino, D., Fuchs, M., Sim, S., Farrar, K. and Martelli, G. 2017a. Improvement of grapevine planting stock through sanitary selection and pathogen elimination. In: Grapevine Viruses: Molecular Biology, Diagnostics and Management. Meng, B., Martelli, G.P., Golino, D.A. and Fuchs, M.F (eds). Springer Verlag, pp. 561-579.

Golino, D., Fuchs, M., Al Rwanih, M., Farrar, K., and Martelli, G.P. 2017b. Regulatory aspects of grape virology: Certification, quarantine and harmonization. In: Grapevine Viruses: Molecular Biology, Diagnostics and Management. Meng, B., Martelli, G.P., Golino, D.A. and Fuchs, M.F (eds). Springer Verlag, pp. 581-598.

Li, R., Fuchs, M., Perry, K.L., Mekuria, T., and Zhang, S. 2017. Development of a fast AmplifyRP Acceler8 diagnostic assay for grapevine red blotch-associated virus. Journal of Plant Pathology, in press.

Martin, I., Vigne, E., Berthold, F., Komar, V., Lemaire, O., Fuchs, M. and Schmitt-Keichinger, C. 2017. The fifty distal amino acids of the 2AHP homing protein of grapevine fanleaf virus elicit a hypersensitive reaction on Nicotiana occidentalis. Molecular Plant Pathology, DOI: 10.1111/MPP.12558.

Ricketts, K.D., Gómez, M.I., Fuchs, M.F., Martinson, T.E., Smith, R.J., Cooper, M.L., Moyer, M. and Wise A. 2017. Mitigating the economic impact of grapevine red blotch: Optimizing disease management strategies in U.S. vineyards. American Journal of Enology and Viticulture, 68:127-135.

Rowhani, A., Daubert, S.D., Uyemoto, J.K., Al Rawhnih, M. and Fuchs, M. 2017. American nepoviruses. In: Grapevine Viruses: Molecular Biology, Diagnostics and Management. Meng, B., Martelli, G.P., Golino, D.A. and Fuchs, M.F (eds). Springer Verlag, pp. 109-126.

Perry, K.L., McLane, H., Thompson, J.R. and Fuchs, M. 2017. A novel grablovirus from non-cultivated grapevine (Vitis sp.) in North America. Archives of Virology, in press.

Perry, K.L., McLane, H., Hyder, M.Z., Dangl, G.S., Thompson, J.R. and Fuchs, M.F. 2016. Grapevine red blotch-associated virus is present in free-living Vitis sp. proximal to cultivated grapevines. Phytopathology, 106:663-670.

Thompson, J.R., Dasgupta, I, Fuchs, M., Iwanami, T., Karasev, A.V., Petrzik, K., Sanfaçon, H., Tzanetakis, I., van der Vlugt, R., Wetzel, T. and Yoshikawa, N. 2017. ICTV virus taxonomy profile: Secoviridae. Journal of General Virology, 98:529-531.

Vargas-Ascencio, J. Perry, K.L., Wise, A and Fuchs, M. 2017. Detection of Australian grapevine viroid in Vitis vinifera in New York. Plant Disease, http://DX.DOI.ORG/10.1094/PDIS-11-16-1587-PDN.

Vargas, J., Al Rwahnih, M., Rowhani, A., Celebi-Toprak, F., Thompson, J.R., Fuchs, M. and Perry, K.L. 2016. Limited genetic variability of American isolates of Grapevine virus E in Vitis sp. Plant Disease, 100:159-163.

Varsani, A., Roumagnac, P., Fuchs, M., Navas-Castillo, J., Moriones, E., Idris, I., Briddon, R.W. Rivera-Bustamante, R., Murilo Zerbini, F. and Martin, D.P. 2017. Capulavirus and Grablovirus: Two new genera in the family Geminiviridae. Archives of Virology, DOI 10.1007/s00705-017-3268-6.

Washington State University

Donda, B. P., Jarugula, S., and Naidu, R. A. 2017. An analysis of the complete genome sequence and subgenomic mRNAs reveals unique features of the ampelovirus, Grapevine leafroll-associated virus 1. Phytopathology 107:1069-1079.

Naidu, R.A. 2017. Grapevine leafroll-associated virus 1. In: Meng B., Martelli G., Golino, D., Fuchs M (eds.), Grapevine Viruses: Molecular Biology, Diagnostics and Management. Springer, Cham, Switzerland, pages 127-139.

Burger, J., Maree, H.J., Gouveia, P., and Naidu, R.A. 2017. Grapevine leafroll-associated virus 3. In: Meng B., Martelli G., Golino, D., Fuchs M (eds.), Grapevine Viruses: Molecular Biology, Diagnostics and Management. Springer, Cham, Switzerland, pages 167-195.

Hoheisel, G., Moyer, M.M., Daniels, C.H., Miller, T.W., Walsh, D., Zasada, I., Naidu, R. A., and Davenport, J.R. 2017. Pest Management Guide for Grapes in Washington. EB0762, 56 pp. (Revised).

Naidu, R.A. 2017. Grafting wine grapes. Good Fruit Grower June 2017. Vol. 68, No. 11, pages 38-39.

Clemson University

A report of Cherry rusty mottle-associated virus in South Carolina. (2017) Poudel, B. & Scott, S.W. Australasian Plant Dis. Notes (2017) 12: 15. https://doi.org/10.1007/s13314-017-0239-4

PA Department of Agriculture

Nikolaeva, E. V., Welliver, R., Rosa, C., Jones, T., Peter, K., Costanzo, S., Davis, R. E. 2017. First Report of Apple (Malus domestica) as a Host of ‘Candidatus Phytoplasma pruni’ in United States. Plant Disease. 101. P. 378.

Nikolaeva, E. V., Lesperance J., Peter, K., Jones, T., Costanzo, S., Davis, R. E. 2017. Phytoplasma survey in Pennsylvania. Phytopathology, S xx (Abstract of 2017 APS Meeting. San Antonio, TX).

Huawei Liu, Liping Wu, Ekaterina Nikolaeva, Kari Peter, Zongrang Liu, Dimitre Mollov, Mengji Cao, Ruhui Li. Discovery and molecular characterization of a new luteovirus identified by high-throughput sequencing from apple (manuscript in preparation).