Annual/Termination Reports:

[02/03/2003] [08/23/2004] [05/25/2005] [04/04/2006]

Report Information

Participants

Alvarez, Juan M.-University of Idaho;
Batchelor, Dallas-Lamb-Weston, Inc.;
Berger, Phil-University of Idaho;
Brown, Chuck-USDA-ARS, Prosser, WA;
Charkowski, Amy-University of Wisconsin;
Corsini, Dennis-USDA-ARS, Aberdeen, ID;
Crosslin, Jim-Washington State University;
Davidson, Robert-Colorado State University;
Franc, Gary-University of Wyoming;
Gray, Stewart-Cornell University;
Gutbrod, Oscar-Oregon State University;
Guzman, Pablo-California Dept. Food and Agriculture;
Hamm, Phil-Oregon State University;
Hane, Dan-Oregon State University;
Henderson, Bob-Oregon State University;
Jaeger, Joy-Oregon State University;
James, Steve-Oregon State University;
Johnson, Dennis-Washington State University;
Malik, Ved-USDA-APHIS;
Marquadt, Steve-North Dakota State Seed Department;
Nolte, Phil-University of Idaho;
Piche, Lisa-North Dakota State University;
Ragsdale, Dave-University of Minnesota;
Sather, Kent-Colorado State University;
Shiel, Pat-University of Idaho;
Singh, Rudra-Agriculture Canada;
Sun, Mike-Montana State University;
Whitworth, Jonathan-Idaho Crop Improvement Assoc. (Univ. of Idaho);
Zink, Rick-Colorado State University;

Brief Summary of Minutes

Following administrative activities (election of officers for the coming year), there was a presentation from Dr. Singh. The presentation focused on characterization and detection of strains of Potato virus Y (PVY). This was timely and useful, considering recent revelations on the introduction and presence of apparently novel strains into the US. Dr. Shiel then followed, presenting data recently obtained that describe methods that can be used to assist in the differentiation of PVY isolates. Analysis of nucleotide sequence data from the Idaho group was presented by Dr. Berger, showing that 4-5 novel isolates have been introduced into the US. One of these is particularly troublesome, as it is a recombinant virus with an O-like coat protein, but otherwise is NTN. This means that it will not be flagged as an N or NTN type serologically. Detection of new isolates in Oregon and Washington was also discussed by Drs. Hamm and Crosslin.



Dr. Hamm presented data on yield reductions due to PVY in the cultivars Norkotah and Shepody, which typically do not show symptoms. In spite of the extremely mild symptoms in these cultivars, significant yield losses due to PVY can occur. Dr. Nolte reported on similar experiments investigating yield losses associated with Potato virus A (PVA). Dr. Ragsdale presented data on the suppression of spread of PVY and Potato leafroll virus (PLRV) in seed potato production. There are certain treatments (insecticide, oil sprays, etc.) that may reduce spread of these viruses by their aphid vectors. Aphid population densities and movement dynamics were also discussed.



Dr. Brown reported on work assessing genetic resistance to potyviruses and Tobacco rattle virus (TRV). TRV presents interesting and unusual challenges, and Drs. Brown and Crosslin elaborated. Dr. Alverez discussed preliminary findings on transmission of PLRV from Solanum sarrachoides. Dr. Gray presented data relating to the functions of the PLRV 17 K, 22K, and 50K proteins, particularly as they related to movement of the virus through the aphid and the ability of PLRV to move systemically in potato. He also reported on aphid genetics as it relates to vector efficiency.



In addition to research results reported, there was considerable discussion pertaining to future research and virus disease management needs, including the need for additional antisera, re-examination of the PVYN Management Plant, and recommendations for dealing with strains of PVY new to the US.

Accomplishments

There was considerable discussion of policy as it relates to the PVYN Management Plan, and agreement that the plan should be modified or eliminated. These ideas will be shared with appropriate regulators. A large multidisciplinary grant was submitted to the IFAFS program from several members of the WCC-89. This proposal was well received, but unfortunately not funded. Discussions were held to prepare the proposal for re-submission. <br /> <br><br /> <br>A major focus of this meeting and the focus of many members of the WCC-89 relates to diagnosis of PVY strains. A proposal to ARS (National Potato Council) was discussed at this meeting, and the proposal was subsequently funded, with funds distributed amoong groups in Idaho, Oregon and Washington. Improved understanding of the new virus strains present in the US should result from this work, as well as improved diagnostic procedures. In the coming year, results of these studies will be shared with the group as well as in appropriate publications. <br /> <br><br /> <br>An important outcome of the meeting not readily evident in publications or other traditional measures of productivity was the opportunity for open discussion and communication among virus researchers, regulatory officials involved with the Federal government and state officials responsible for enforcing potato seed certification regulations. Ultimately, viral research and regulations that target virus diseases of potato need to consider the impact of each particular virus on the potato industry. Practical approaches for virus detection and regulation must be developed in order to facilitate incorporation of research results into seed potato production programs.

Publications

Crosslin, J.M., Hamm, P.B., Eastwell, K.C., Thornton, R.E., Brown, C.R., Corsini, D., Shiel, P.J., and Berger, P.H. 2002. First report of PVYN potyvirus on potatoes in the northwestern United States. Plant Disease 86:1177.

Impact Statements

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Report Information

Participants

Alvarez, Juan (jalvarez@uidaho.edu) University of Idaho;
Batchelor, Dallas (dbatchelor2b@charter.net) Lamb Weston;
Berger, Phil (Philip.h.berger@aphis.usda.gov) USDA/APHIS;
Bewick, Tom (tbewick@reeusda.gov) USDA/CSREES;
Brown, Chuck (cbrown@pars.ars.usda.gov) USDA/ARS;
Charkowski, Amy (amyc@plantpath.wisc.edu) University of Wisconsin;
Crosslin, Jim (jcrossli@tricity.wsu.edu) Washington State University;
Davidson, Rob (rddavid@coop.ext.colostate.edu) Colorado State University;
Gray, Stewart (smg3@cornell.edu) Cornell University;
Hall, Darren (dhall@uidaho.edu)-University of Idaho;
Hamm, Phil (phillip.b.hamm@oregonstate.edu) Oregon State University;
Hane, Dan (dan.hane@oregonstate.edu) Oregon State University;
Franc, Gary (francg@uwyo.edu) University of Wyoming;
Haslar, Rick (rhaslar@lamar.colostate.edu) Colorado State University;
Henderson, Bob (Robert.henderson@oscs.orst.edu) Oregon State University;
Lambert, Dave (dlambert@ndsuext.nodak.edu) North Dakota State University;
Lent, Melinda (melindab@uidaho.edu)University of Idaho;
Lorenzen, Jim (jiml@uidaho.edu)University of Idaho;
Malik, Ved (Vedpal.s.malik@usda.gov) USDA;
Marquardt, Steve (smarquardt@state-seed.ndsu.nodak.edu) North Dakota State Seed Department;
McMorran, Jeff (jeff@oscs.orst.edu)Oregon State University;
Munyaneza, Joe (munyaneza@yarl.ars.usda.gov)USDA/ARS;
Nolte, Phil (pnolte@uidaho.edu) University of Idaho;
Pantoja, Alberto (ffap@uaf.edu) USDA/ARS/University of Alaska, Fairbanks;
Pappu, Hanu (hrp@wsu.edu) Washington State University;
Piche, Lisa (Lisa.Piche@ndsu.nodak.edu) North Dakota State University;
Ragsdale, David (ragsd001@7mn.edu) University of Minnesota;
Singh, Rudra (singhr@agr.gc.ca)Agriculture & AgriFood Canada;
Snell, Rue (slvctr@coop.ext.colostate.edu)Colorado State University;
Sun, Mike (msun@montana.edu)Montana State University;
Thornton, Mike (miket@uidaho.edu)University of Idaho;
Whitworth, Jonathan (whitworth_idahocrop@juno.com)Idaho Crop Improvement Association

Brief Summary of Minutes

Brown convened 1:10 pm. Lorenzen noted new AA, Bohach, couldn't attend but extended best wishes. Brown requested approval of last meeting's minutes. Hane had 1 amendment: Whitworth brought up the point about PVY-N management plan. Motion approved as amended; minutes approved. Brown reminded about accomplishments for 2006 renewal and to secure funding for potato virus-related projects.

Bewick gave overview of funding opportunities and distributed handouts of CSREES programs. He suggested group start working on renewal project and importance of a good accomplishment report. He described USDA National Plant Diagnostic Network. Surveillance is major part of network/includes training extension agents and growers. The U MD NIMSS website lists all multistate projects. Participants must fill out Appendix E for WCC-89 membership.

Thompson: PVY is concern in Norkotah and Shepody. Gemstar Russet appears to be a sponge. Must investigate what isolation distance is effective and what management recommendations reduce incidence. Susceptibility difference between varieties was noticed. ie, Russestt Burbank had more PVA; no PVA was seen in A9014-2. She gave an update on testing for PYV NTN and corky ring spot.

McMorran: 1) OR concern about rouging based on foliar symptoms of TRV, since 95% of potatoes show no foliar symptoms. Tuber symptoms are better indication of infection. 2) National standards seem to be based on politics rather than science. Eg. OR allows G5 with 2% PVY infection. However, they were asked if this could be lowered to 1.5% to meet a common national standard. Is there valid scientific reason for requiring pre-commercial to be certified at 1.5% but not 2.0%? 3) According to Schrages UNECE report regarding PMTV, TRV & PNYn. It was decided that testing on tubers with necrotic symptoms was not practical yet. So why is it considered practical in the US? 4) In the case of aster yellows, OR has no tolerance for disease in field, but we do have tolerances in greenhouse. Should we be concerned about this disease in the seed programs? Thompson expressed concern about difficulties training field inspectors on PMTV. Only images are being used as import of PMTV under permit is not allowed.

Haslar: There was a drop of 2600 acres in seed production due to drought and PVY. Some growers could not manage PYV. New PVY resistant varieties on horizon. One tentatively named RioGrande Russet. No recombinant PYV found in CO. Some leaf roll noticed. TRV seen in commercial crop but not in seed crop.

Marquardt: No TRV and PMTV in ND.
Charkowski: PYV was big issue. Incidence was 4% in 2001, lower in 2002, but back to 4% in 2003. Contributory factor may be planting of Russest Norkotah. However, this year had lowest ever seen in winter test. Border crops ie. rye grass and oils seemed to help.

Gray: PVY not big issue.

Lambert: PVA a problem for first time. PMTV symptoms being studied. So far, not found in the field. Tubers with necrotic spots found in Ontario and PEI. Cutting tubers to find symptoms seems the most reliable approach for diagnosis.

Sun: Gave update on testing for PVY-N. In 2000, 100% tested. ELISA showed one + in each of Ranger, Umatilla, A*410, and Liberty. PVY-N not detected last 2 years. 100% of nuclear and G1 tested for PVY and PVX. For G2, 200 leaves per acre were tested. Use of Admire may have led to drop in PVY infection 2002.

Guzman: Only 3 are growers in CA; they buy seed from Canada and WA.

Singh: PVY continues to be a problem. Those using oils and rouging produce good seed. Some provinces not allow monitoring. As a result incidence is going up.

Research updates - PVY

Gray: Presented results of a ME and NY survey. Samples from seed lots from other states, seed farms and commercial farms were surveyed. Symptomatic plants were tested. In imported lots 97% had PVY, 68% PVS and 35% PVX. This does not mean high incidences necessarily just some infection in that percentage of lots. ME and NY farms had lower virus incidence than imported lots. Asymptomatic plants were also tested; 46% had PVS 1% PVY and 1%vPVX.

Testing of PYV isolates included inoculating tobacco for necrosis and ELISA using PVY-N specific monoclonal antibody. Some samples were positive without necrosis. PVY-N produces systemic infection in Allegheny; PVY-O causes hypersensitive response (does not go systemic). None of the isolates infected Eva which is extremely resistant. One of isolates exhibited PVY-NTN symptoms. Attempts to use micro tubers for developing assays were not successful. Screening of a potato cDNA library showed the presence of sequences related to cherry rasp leaf nepovirus. Keith Perry of Cornell works on this.

Whitworth: Breeding and virus indexing. Advanced clones of Bannock Russet are highly resistant to PVY. Results of a 2 year test were shown. Described symptoms of PVY complex in foliage and tubers. Using PVY strains: N, NTN, N:O, and cultivars: Russet Burbank, Ranger Russet, Alturas, Yukon Gold at two temperature, 10 & 20 C. Lower temp resulted in less symptoms. Provided a suggested definition of the PVY complex. The group felt that this is a very useful and worthwhile effort which is likely to increase the understanding of PYV complex and its diagnosis. A subcommittee formed to review above and suggest a set of descriptors for each strain in PVY complex. Brown nominated Whitworth, Hamm, Berger and Crosslin to the sub-committee.

Hall: Provided update on markers associated with PVY resistance using S. andrigena. There was a higher manual transmission of PVY-N than PVY-O.

Crosslin: Described the results of ELISA on samples from Phil Hamm and some transgenic lines. The MAb from Agdia, MAb4C3, detects all PVY isolates. He made antisera to synthetic peptides to develop strain-specific antisera but the antisera did not work. He gave an update on the use of RT-PCR to identify N/NTN or PVY O.

Hamm: Discussed PVY symptoms and summarized the results of the occurrence of PVY-N, N:O in seed lots from various states and provinces. N, NTN and N:O seemed to be present in most states and Canadian provinces.

Piche (Gudmestad's lab): Described work characterizing 58 field isolates from ID, MN, ND, NE, NV, OR, TX and WA. ELISA testing of samples using Agdia antisera and RT-PCR using primers from published reports (J Vir Meth 104:40) to identify PYV complex components. Duplex PCR using S6, S7 and A primers (J Vir Meth 113:69) and recombinant point PCR characterized these isolates. 18% of the isolates did not fit the PVY demarcation. Some N:O had atypical symptoms. Among the PVY N-like isolates 6 types were distinguishable based on tobacco host reaction, production of necrosis in tester varieties and sequence data identifying recombination sites in the viral genome. Adjourned.

Brown opened the meeting 4/7 at 8:00 AM. He suggested the group prepare a statement of accomplishments for USDA and potato commissions.

Lorenzen: Presented sequencing results, started by Berger and Shiel, now carried on by him. Alturas (N:O) was completed and found to be 93% identical with the Hungarian strain (N strain). Confusion exists in literature about the nature of PVY-N/NTN host response. Based on sequence comparisons, isolate 423 provided by P Hamm appears to be a typical European NTN, shared 99.3% homology with the Hungarian NTN and 93.2% homology with the Swiss PVY-N. The "Montana" isolate showed 99.2% identity with the Swiss PYV N (X97895); the "RRA2" isolate was very similar to the NA-NTN/NA-N strains (99.0%, 98.9%) previously described by Singh. He suggested that there may be some evidence of gene conversion.

Singh: Described a new recombinant isolate from Canada. Survey done in Manitoba potatoes showed a PVY-N like which upon further characterization turned out to be a recombinant PVY sharing PVY-N pathotype and PVY-O serotype, considered as PVY N:O. He suggested that the spread of PVY N:O in North America was due to the PVY-O like serological reaction of this isolate. Complete genome of this recombinant isolate was sequenced. The 5 was N-like and 3 was O-like. Hence the anomaly in serological reaction. He described a multiplex RT PCR for specific detection of recombinant PYV isolates and showed the primers specific for recombinant junctions, RJ1, RJ2 and RJ3. He later described a new extraction method for RNA from potatoes that is suitable for conducting RT PCR. The key feature of this method is the use of a liquid form of Triton X ATN available from Sigma.

Lent: Described the effect of PVA on yield of Russet Norkotah. PVA was found in 1996 in ID and became serious in 1999. It causes mild symptoms. The objective of the study was to determine the effect of various levels of seed borne PVA on yield of Norktoah. Field data from 2000, 2001, and 2002 at Parma, ID and Hermiston, OR were presented. Burbank showed a 0.1 ton reduction with 1% seed borne PVA infection per acre, whereas Norkotah showed no reduction in yield with seedborne PVA infection. Discussion followed. Chuck Brown asked if we should ignore PVA like we did with PVS. Stewart Gray asked if there is any synergism with other viruses and suggested that caution should be exercised. R.P. Singh mentioned that Bud Wright published some data on this in Potato Journal.

Berger initiated discussion on deregulating PVY. Group discussed PVY management plan with respect to US, Canada, and Mexico, and the need to establish tolerance levels. Brown and Hamm suggested resistance should be the long term, high priority goal for managing PYV. Berger moved the group recommend above; Colleen seconded; passed unanimously.

It was mentioned that there is a need to recognize that releasing new varieties should take into consideration the detrimental effect of potato cultivars as potential symptomless carriers of PYV. This could be a quality factor. A motion was proposed and passed unanimously.

Lorenzen: Gave an update on volatiles in case of PLRV and he mentioned that work is in progress on QTLs. Singh said that CO potato beetle prefers PLRV-infected potatoes. Discussion followed and Juan raised the point of what attracts green peach aphids. He described some of his on-going research on the role of night shade and the behavior of winged and wingless aphids and the progression of disease in potatoes. Henderson asked if there is any data on change in volatiles due to insecticidal treatment.

Crosslin: He showed results of his research on the role of weeds in TRV epidemiology. Some weeds were tested for TRV and reproduction of stubby root nematode. He gave a list of weeds that are hosts for nematodes but not for the virus. He showed the results of detection of TRV in hairy nightshade plants by RT PCR in berries and seed of systemically infected plants. No seed transmission detected. TRV was confined to roots. Discussion followed on the role of weeds in TRV spread. TRV was seen occasionally in commercial fields, with zero tolerance in CO and ID.


Elections
Brown invited nominations for the position of Secretary. Hamm nominated Alvarez. Horton seconded. Uunanimous.

Venue: Next meeting in Phoenix, date TBD.

Crosslin: gave update on potato phytoplasma including phytoplasma taxonomy. He presented PCR results of potato phytoplasma detection and compared single vs nested PCR. Some nested PCR gave false +s and some gave false -s. He designed primers specific to r-proteins which seemed to improve specificity. Hamm mentioned that controlling leafhoppers early may reduce disease. Munyaneza discussed population dynamics of leaf hoppers and remarked that we need to id the vector so that application timing can be refined. Franc suggested grafting of symptomatic potatoes to tomatoes since leafhoppers do not survive on tomato.

PMTV
Hamm asked the group about the latest situation regarding PMTV. Based on the information on testing of US potatoes by Canada, Nolte mentioned that the ID Dept. of Ag extensively sampled the area identified by the Canadian report. Results are not available. Lambert said that 32 of 2000 samples were positive in ME. Thompson commented that tubers should be tested instead of leaves and asked if samples can be tested in a central location. Singh mentioned a proposal to develop standardized protocols for screening PMTV under controlled conditions. Foliar symptoms are not common for PMTV and hence tuber testing is required. A motion was made that tuber testing should be used for diagnosis of PMTV. Singh pointed out that foliar symptoms referred to as stem mottle were described in Europe. A Dutch Plant Pathology textbook being translated to English has chapter on stem mottle.

Brown asked if there is any transgenic work in potatoes. Appears there is none.

PVY management plan
Whitworth updated on the status of the plan. He motioned that the group ask NPC Subcommittee on Certification that the document be distributed for final comments with a reasonable amount of comment period allowed prior to final signatures. Seconded by Thompson/unanimously passed.

Adjourned 3:00 pm.

The following passed unanimously:

1. Critical need to establish criteria for describing the PYV complex. Sub-committee formed. Brown nominated Whitworth, Hamm, Berger and Crosslin.

2. Berger moved highest priority be given to develop potato cultivars immune to PVY complex (non-strain specific). Additionally, the group recognizes there should be an official recognition of the fact that releasing new varieties latent or asymptomatic carriers of viruses is detrimental to the industry in that the necrotic symptom of the tubers is a quality factor. Thompson seconded.

3. Hamm moved that we remove foliar symptoms of tobacco rattle virus (TRV) in management plant because foliar symptoms are not reliable in TRV diagnosis. Davidson seconded.

4. Thompson moved we would not recommend identification of potato mop top virus based on foliar testing until such time it is proven to be reliable. Diagnosis should continue to be based on ELISA testing of tubers. Seconded by Davidson.

5. Whitworth proposed WCC-89 ask the NPC Sub Committee on Certification that the document be distributed for final comments with a reasonable amount of comment period allowed prior to final signatures. Thompson seconded.

6. Brown moved that WCC-89 recognize leadership of outgoing AA, R Heimsch. Hamm seconded.

Accomplishments

Ongoing efforts in New York by Dr. Steward Gray from Ithaca, NY and his collaborators include a survey done in ME and NY. Samples from imported seed lots from other states, seed farms and commercial farms were surveyed and symptomatic plants were collected and tested. In imported lots 97% had PVY, 68% PVS and 35% PVX at some level of infection i.e., at least one infected sample. This does not mean high incidences necessarily just some infection in that percentage of lots. ME and NY farms had lower virus incidence than imported lots. Asymptomatic plants were also tested. Results showed 46 % had PVS 1% PVY and 1%vPVX. Testing showed that variety, Eva was highly resistant. Screening of a potato cDNA library showed the presence of sequences related to cherry rasp leaf nepovirus. <br /> <br /> As part of a continuing effort, Dr. Jonathan Whitworth of USDA-ARS from Kimberly, ID developed advanced clones of Bannock Russet that are highly resistant to PVY. He compiled the symptomatology of the PVY complex in foliage and tubers, using PVY strains: N, NTN, N:O, and cultivars Russet Burbank, Ranger Russet, Alturas, Yukon Gold at two temperature, 10 and 20 C. Provided a suggested definition of the PVY complex. The group felt that this is a very useful and worthwhile effort which is likely to increase the understanding of the PYV complex and its diagnosis. A subcommittee is formed to review the above and to suggest a set of descriptors for each strain in the PVY complex. <br /> <br /> Darren Hall and Jonathan Whitworth of USDA-ARS, Kimberly, ID are exploring markers associated with PVY Resistance, using Solanum andrigena.<br /> <br /> <br /> Jim Crosslin of USDA-ARS, Prosser, WA has standardized a RT-PCR assay to identify N/NTN or PVY-O.<br /> <br /> <br /> Testing of seed lots by Phil Hamm of Oregon State University, Hermiston, OR showed the occurrence of PVY-N, N:O, and NTN in various states and Canadian provinces which highlighted the need for continued monitoring of seed for these viruses. <br /> <br /> Neil Gudmestad, North Dakota State University, ND, used various sets of primers to identify the various components of PYV complex in ND. Novel PCR-based approaches such as duplex PCR and recombinant point PCR are being used to characterize various PYV isolates at molecular level. Based on this work, new isolates are found that did not fit the PVY demarcation.<br /> <br /> Several PYV isolates were sequenced in the laboratory of Jim Lorenzen of University of Idaho, Moscow, ID, which will be useful in determining the sequence identity of several PVY variants. Specific accomplishments include, near completion of whole-genome sequencing of 10 PVY isolates, and PCR assays designed for three newly discovered PVYN:O recombinant junctions. <br /> Plans for coming year include, sequencing another 6 to 10 PVY genomes selected by collaborators for novel genotype/phenotype combinations, development of multiplex PCR assay to more accurately differentiate known PVY strain types/recombinants in N. America, development of an infectious PVY clone system to use in hypothesis testing, determination of the effect of PVY, PLRV and PLRV constructs on gene expression of potato leaves using cDNA microarrays (while collaborators determine effect on foliar metabolite content and volatile emission). <br /> <br /> As part of an ongoing effort to understand the PYV complex, RP Singh of Agriculture and Agri-Food Canada, New Brunswick, found a new recombinant isolate in Canada. Survey done in Manitoba potatoes showed a PVY-N like which upon further characterization turned out to be a recombinant PVY sharing PVY-N pathotype and PVY-O serotype, considered as PVY N:O. He suggested that the spread of PVY N:O in North America was due to the PVY-O like serological reaction of this isolate. Complete genome of this recombinant isolate was sequenced. The 5? was N-like and 3? was O-like which may be the reason for the observed anomaly in serological reaction. A multiplex RT PCR assay for specific detection of recombinant PYV isolates was developed and primers specific for recombinant junctions, RJ1, RJ2 and RJ3 are developed. <br /> A new extraction method for RNA from potatoes that is suitable for conducting RT PCR was developed.<br /> <br /> <br /> Based on field evaluations over a three-year period (2000-2002), the effect of PVA on yield of selected varieties, carried out by Melinda Lent of University of Idaho, showed that Burbank showed a 0.1 ton reduction with 1% seed borne PVA infection per acre, whereas Norkotah showed no reduction in yield with seed borne PVA infection. <br /> <br /> <br /> Phil Nolte, Alvarez, Whitworth and Thompson of University of Idaho and USDA-ARS are currently investigating the possiblity of managing PVY-PVA mosaic using early vine kill combined with application of crop oil for seed producers. <br /> <br /> Dan Hane of Oregon State University, Hermitson, OR is participating in the second year of a national PVY variety susceptibility evaluation for entries received from breeders across the U.S. The project entitled, Characterization of symptom expression to PVY of potato breeding lines advanced from breeding programs in the US and the identification of resistance earlier in breeding, is led by Chritian Thill. Selections from Colorado, Maine, Minnesota, New York, Texas Wisconsin, and the USDA/ARS have been evaluated. Sixty eight entries were evaluated in 2003 of which 4 clones were designated as asymptomatic and 2 with unreadable symptoms in two of four replications in the Hawaiian winter grow-out. Part of the effort is also directed at the environmental component for symptom expression. This season, 105 clones are being evaluated. This effort is directed at identifying asymptomatic clones being advanced in breeding programs as well as comparing the environmental differences between Minnesota and Oregon.<br /> Additionally, Phil Hamm & Dan Hane evaluated 8 cultivars this past season for their ability to acquire PVY in a natural field setting. Four of the clones are noted for their spongeeffect when it comes to acquiring PVY Shepody, Russet Norkotah, Gem Russet, and GemStar. The other 4 are not generally as problematic Russet Burbank, Ranger Russet, Umatilla Russet, and Alturas. The purpose is to try to understand whether varieties do in fact become infected with PVY at different rates under field conditions and if so, try to define contributing factors to the differences. This would be of particular use in seed growing areas for managing PVY in seed fields.<br />

Publications

Boydston, R.A., H. Mojtahedi, J.M. Crosslin, P.E. Thomas, T. Anderson, E. Riga. 2004. Evidence for the influence of weeds on corky ringspot persistence in alfalfa and Scotch spearmint rotations. Am. J. Pot. Res. 81:215-225.<br /> <br /> <br /> Crosslin, J.M., P.B. Hamm, K.C. Eastwell, R.E. Thornton, C.R. Brown, D. Corsini, P.J. Shiel, and P.H. Berger. 2002. First report of the necrotic strain of Potato virus Y (PVYN) potyvirus on potatoes in the northwestern United States. Plant Disease 86:1177.<br /> <br /> <br /> Crosslin, J.M., P.E. Thomas, and R.W. Hammond. 2003. Genetic variability of genomic RNA 2 of four tobacco rattle tobravirus isolates from potato fields in the northwestern United States. Virus Research 96:99-105. <br /> <br /> <br /> Mojtahedi, H., R.A. Boydston, P.E. Thomas, J.M. Crosslin, G.S. Santo, E. Riga, and T.L. Anderson. 2003. Weed hosts of Paratrichodorus allius and Tobacco rattle virus in the Pacific northwest. Am. J. Pot. Res. 80:379-385.<br /> <br /> <br /> Mojtahedi, H., J.M. Crosslin, P.E. Thomas, G.S. Santo, C.R. Brown, and J.H. Wilson. 2002. Impact of wheat and corn as rotational crops on corky ringspot disease of Russet Norkotah potato. Am. J. Pot. Res. 79:339-344.<br /> <br /> <br /> Mojtahedi, H, G.S. Santo, P.E. Thomas, J.M. Crosslin, and R.A Boydston. 2002. Eliminating tobacco rattle virus from viruliferous Paratrichodorus allius and establishing a new virus-vector combination. J. Nematology 34:66-69.<br /> <br /> <br /> Nolte, P., JL Whitworth, MK Thornton and CS McItosh. 2004. Effect of Seedborne Potato virus Y on Performance of Russet Burbank, Russet Norkotah and Shepody Potato. Plant Disease 88:248-252.<br /> <br /> <br /> Piche, L.M., R. P. Singh, X. Nie, and N. C. Gudmestad. 2004.. Diversity Among Potato virus Y Isolates Obtained from Potatoes Grown in the United States. Phytopathology 94:1368-1375.<br /> <br /> <br />

Impact Statements

1. Facilitating the interstate cooperation to detect, analyze and determine the distribution of PVY strains.
2. Informing the USDA officials about the status of the PVY strain problem.
3. Interacting with regulatory officials on the management of tuber necrotic viruses.
4. Facilitating the proper testing in seed certification agencies to properly assess the PVY strain diversity in the potato seed industry.
5. Facilitating the assessment of the potato mop top threat.
6. Assisting seed certification programs in establishing rules regarding tolerance for tobacco rattle virus in seed.
7. Assessing new testing technology options so that seed certification agencies can properly evaluate technology upgrades.
8. Establishing resolutions to guide policymakers on recommended research areas to solve virus problems in potato.
9. Facilitating team efforts to establish beet leafhopper as sole vector of the phytoplasma
10. Discovery of Leafhopper Transmitted Virescence Agent as the sole incitant of the recent outbreak of Potato Purple Top in Washington State.

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Report Information

Participants

Alvarez, Juan Manuel(jalvarez@uidaho.edu)-University of Idaho;
Batchelor, Dallas(dbatchelor2b@charter.net)-Lamb Weston;
Bateman, Melinda(melindab@uidaho.edu)-University of Idaho;
Berger, Phil(Philip.h.berger@aphis.usda.gov)-USDA/APHIS;
Bohach, Greg(gbohach@uidaho.edu)-University of Idaho;
Brown, Chuck(cbrown@pars.ars.usda.gov)-USDA/ARS;
Crosslin, Jim(jcrosslin@pars.ars.usda.gov)-USDA/ARS;
Davis, Jeff, (davis271@umn.edu)-University of Minnesota;
Gray, Stewart (smg3@cornell.edu)-USDA-ARS;
Guzman, Pablo (pguzman@ucdavis.edu)-California Department of Agriculture-Davis;
Hall, Darren (dhall@uidaho.edu)-USDA-ARS;
Hamm, Phil (phillip.b.hamm@oregonstate.edu)-Oregon State University;
Hane, Dan (dan.hane@oregonstate.edu)-Oregon State University;
Franc, Gary (francg@uwyo.edu)-University of Wyoming;
French, Allan (Allan.French@simplot.com)-Simplot;
Laug, Sherry(slaug@idahocrop.com)-Idaho Crop Improvement Association;
Lorenzen, Jim (jiml@uidaho.edu)-University of Idaho;
Malik, Ved (Vedpal.s.malik@usda.gov)-USDA-APHIS;
Marquardt, Steve (smarquardt@state-seed.ndsu.nodak.edu)-North Dakota State Seed Department;
Munyaneza, Joe (munyaneza@yarl.ars.usda.gov)-USDA/ARS;
Navarre, Roy (rnavarre@pars.ars.usda.gov)-USDA/ARS;
Nolte, Phil (pnolte@uidaho.edu)-University of Idaho;
Pappu, Hanu (hrp@wsu.edu)-Washington State University;
Piche, Lisa (Lisa.Piche@ndsu.nodak.edu)-North Dakota State University;
Sather, Kent(ksather@lamar.colostate.edu)-Colorado State University;
Srinivasan, Babu (srin8536@uidaho.edu)-University of Idaho;
Thompson, Colleen (cthompson@idahocrop.com)-Idaho Crop Improvement Association;
Whitworth, Jonathan(jwhit@uidaho.edu)-USDA-ARS

Brief Summary of Minutes

The full minutes are included in the attached file. The following is a brief summary.

Discussions surrounding PVY (effects on seed industry, difficulties in dealing with newer strains, effects on seed programs and international movement of potatoes, management schemes, insect involvement, variety response differentials, detection and strain differentiation, genetic resistance, reviews of current research) dominated this meeting session, indicating the importance and difficulties in dealing with this virus. The following motion was formulated from those discussions:
A motion was made: C. Brown proposed that the WERA-89 should form a committee that would formulate a statement on PVY management at a national level by July 1, 2005. S. Gray seconded the motion and it was unanimously approved. C. Brown will chair the committee and Gray, Whitworth, Hamm, and Thompson will be also part of the committee.

Additionally, it was reported that evidence indicates an increase in the incidence of Tobacco Rattle Virus and Alfalfa Mosaic Virus as well as in PVY strains.

Discussions on PLRV covered genetic resistance, inoculum sources, and alternate hosts.

Molecular and biochemical resistance to Tobacco Mosaic Virus (TMV) were presented. Finding a local lesion host for TMV would be useful in screening for this virus. Induced resistance to pests by potato was also discussed.

Identification of the casual agent of Purple Top (Columbia Basin Potato Purple Top Phytoplasma) in the Columbia basin provided evidence that this was not in the aster yellows phytoplasma group. This beet leafhopper transmitted viralescence agent (BLTVA) can cause 15% yield losses in potato.

Jim Crosslin was unanimously elected to the position of secretary. Juan Alvarez will move into the position of vice-chair, and Hanu Pappu acquires the chair position for the coming year.

Accomplishments

WERA-089 input provided the expertise required to establish a necrotic virus management plan between the U.S. and Canada which was signed and funding for a national survey portion was secured. Criteria for describing the PVY complex was developed which was included in this virus management plan. Some variety differentials were defined. Also, a tuber survey was completed indicating an increase in PVY in general.<br /> <br /> Methods for identifying PVY strains with ELISA and PCR have been refined.<br /> <br /> Facilitated the proper testing for seed certification agencies to accurately assess the PVY strain diversity in the potato seed industry.<br /> <br /> Assessing new testing technology options so that seed certification agencies can properly evaluate technology upgrades.<br /> <br /> Establishing resolutions to guide policymakers on identifying and establishing priority research areas to solve virus problems in potato.<br /> <br /> Facilitated the assessment of the potato mop top threat. <br /> <br /> Facilitating a multistate cooperative team effort to establish the beet leafhopper as the sole vector of the phytoplasma that causes purple top diseases in the Columbia Basin.<br /> <br /> Characterization and establishment of the etiology of purple top disease in the Columbia Basin and discovery of the insect vector and its phenology. <br /> <br /> Up-dated participants on new and on-going research efforts directed at virus (& phytoplasma) problems in potatoes.<br /> <br /> <br />

Publications

Alvarez, J.M. 2004. Potato insect pests. In J.L. Capinera (ed.), Encyclopedia of Entomology. Klower Academic Press, 1803-1816. <br /> <br /> Alvarez, J.M. 2004. Nightshade plants are an aphid magnet and also harbor potato viruses. Potato Grower, 33: 44-46. <br /> Alvarez, J.M. and R. Srinivasan. 2005. Evaluation of hairy nightshade as an inoculum source for the aphid-mediated transmission of potato leafroll virus. J. Economic Entomol. In press.<br /> <br /> Alvarez, J.M. and R. Srinivasan. 2005. Evaluation of hairy nightshade as an inoculum source for the aphid-mediated transmission of potato leafroll virus. J. Economic Entomol. In press.<br /> <br /> Boydston, R.A., H. Mojtahedi, J.M. Crosslin, P.E. Thomas, T. Anderson, E. Riga. 2004. Evidence for the influence of weeds on corky ringspot persistence in alfalfa and Scotch spearmint rotations. Am. J. Pot. Res. 81:215-225. <br /> <br /> Crosslin, J.M., J.E. Munyaneza, A. Jensen, and P.B. Hamm. 2005. Association of beet leafhopper (Hemiptera: Cicadellidae) with a clover proliferation group phytoplasma in Columbia Basin of Washington and Oregon. J. Economic Entomol. 98:279-283. <br /> <br /> Crosslin, J.M., P.B. Hamm, P.J. Shiel, D.C. Hane, C.R. Brown, and P.H. Berger. 2005. Serological and molecular detection of tobacco veinal necrosis isolates of Potato Virus Y (PVYN) from potatoes grown in the western United States. Am. J. Pot. Res. (in press; accepted Dec. 7, 2004).<br /> <br /> Nolte, P., JL Whitworth, MK Thornton and CS McItosh. 2004. Effect of Seedborne Potato virus Y on Performance of Russet Burbank, Russet Norkotah and Shepody Potato. Plant Disease 88:248-252. <br /> <br /> Novy, R.G., Alvarez, J.M., Corsini, D.L., Nasruddin, A., Radcliffe, E.B., and Ragsdale, D.W. 2004. Resistance to PVY, PLRV, PVX, green peach aphid, colorado potato beetle, and wireworm in the progeny of a tri-species somatic hybrid. Am. J. Pot. Res. 81 (1): 77-78. <br /> <br /> Piche, L.M., R. P. Singh, X. Nie, and N. C. Gudmestad. 2004. Diversity Among Potato virus Y Isolates Obtained from Potatoes Grown in the United States. Phytopathology 94:1368-1375.<br /> <br />

Impact Statements

1. Potato virus Y and Potato mop top virus threatened the potato seed and production industries in the U.S. and Canada and caused international trade barriers. Much of the new knowledge about this group of viral diseases was developed through investigations, conducted by this WERA. Our work helped develop an updated and a more effective virus management plan. The trade barriers between the U.S. and Canada were reduced and managed effectively.
2. A severe outbreak of a previously unrecognized potato disease caused extensive crop losses in the Columbia basin from 2002-04. An interdisciplinary team was established and undertook extensive research and extension efforts and led to the identification of the causative agent, a new phytoplasma, and its insect vectors. Identification of the agent and determination of the phenology allowed the group to establish appropriate management practices resulting in complete control.

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Report Information

Participants

Juan Manuel Alvarez, University of Idaho, Aberdeen, ID; Dallas Batchelor, WA; Greg Bohach, University of Idaho, Moscow, ID; Chuck Brown, USDA-ARS, Prosser, WA; Tom Bewick, USDA-CSREES, D.C.; Jim Crosslin, USDA-ARS, Prosser, WA; Nick David, Oregon State University, Hermiston, OR; Rob Davidson, Colorado State University, Center, CO; Stacy Gieck, Oregon State University, Hermiston, OR; Darren Hall, USDA-ARS, Aberdeen, ID; Phil Hamm, Oregon State University, Hermiston, OR; Dan Hane, Oregon State University, Hermiston, OR; Gary Franc, University of Wyoming, Laramie, WY; Stewart Gray, USDA-ARS, Ithaca, NY; Sherry Laug, Idaho Crop Improvement, Idaho Falls, ID; Jim Lorenzen, University of Idaho, Moscow, ID; Ved Malik, USDA-APHIS; Steve Marquardt, ND; Mel Martin, Simplot, WA; Joe Munyaneza, USDA-ARS, Wapato, WA; Roy Navarre, USDA-ARS, Prosser, WA; Phil Nolte, University of Idaho, Idaho Falls, ID; Cindy Nolte, University of Idaho, Idaho Falls, ID; Hanu Pappu, Washington State University, Pullman, WA; Mark Pavek, Washington State University, Pullman, WA; Lisa Piche, North Dakota State University; David Ragsdale, University of Minnesota; Gary Secor, North Dakota State University; Rue Snell, Colorado State University, Center, CO; Babu Srinivasan, University of Idaho, Aberdeen, ID; Mike Sun; Montana State University, Bozeman, MT; Chet Sutula, Agdia, Elkhart, IN; Colleen Thompson, Idaho Crop Improvement, Idaho Falls, ID; Jonathan Whitworth, USDA-ARS, Aberdeen, ID.

Brief Summary of Minutes

To see complete version of minutes Click on old minutes attachment below.

Accomplishments

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

Publications

Alvarez, J.M. and P.J.S. Hutchinson, 2005. Managing hairy nightshade to<br /> reduce potato viruses and insect vectors. Outlooks on Pest Management<br /> Journal. 16 (6): 249-252.<br /> <br /> Alvarez, J.M. and R. Srinivasan. 2005. Evaluation of hairy nightshade as an<br /> inoculum source for the aphid-mediated transmission of potato leafroll virus.<br /> Journal of Economic Entomology. 98: 1101-1108. <br /> <br /> Crosslin, J.M., G.J. Vandemark, and J.E. Munyaneza. 2006. Development of<br /> A real-time, quantitative PCR for detection of the Columbia Basin potato<br /> purple top phytoplasma in plants and beet leafhoppers. Plant Dis.<br /> 90:663-667.<br /> <br /> Lorenzen, J.H., T. Meacham, P.H. Berger, P.J. Shiel, J.M. Crosslin, P.B.<br /> Hamm, and H. Kopp. 2006. Whole genome characterization of Potato virus<br /> Y isolates collected in the western USA and their comparison to isolates<br /> from Europe and Canada. Arch. Virol. 151:1055-1074.<br /> <br /> Munyaneza, J.E., J.M. Crosslin, and J.E. Upton. 2006. Beet leafhopper<br /> (Hemiptera: Cicadellidae) transmits the Columbia Basin potato purple top<br /> phytoplasma to potatoes, beets, and weeds. J. Econ. Entomol.<br /> 99:268-272.<br /> <br /> Crosslin, J.M., P.B. Hamm, P.J. Shiel, D.C. Hane, C.R. Brown, and P.H.<br /> Berger. 2005. Serological and molecular detection of tobacco veinal<br /> necrosis isolates of Potato Virus Y (PVY-N) from potatoes grown in the<br /> western United States. Am. J. Potato Res. 82:263-269.<br /> <br /> Crosslin, J.M., J.E. Munyaneza, A. Jensen, and P.B. Hamm. 2005.<br /> Association of beet leafhopper (Hemiptera: Cicadellidae) with a clover<br /> proliferation group phytoplasma in Columbia Basin of Washington and<br /> Oregon. J. Econ. Entomol. 98:279-283.<br /> <br />

Impact Statements

1. This is the first time X. fastidiosa has been associated with a disease of potatoes. The stolbur-like phytoplasma also has not previously been associated with potatoes. The discovery of X. fastidiosa, in particular, is of major concern because strains of this pathogen cause serious diseases of many crops including Pierce&lsquo;s disease of grapes and variegated chlorosis of citrus. Some strains of X. fastidiosa are considered select agents by USDA-APHIS. Therefore, this pest is of trade and quarantine significance and could potentially cause significant economic losses in many crop plants. The complete understanding of the etiology of zebra chip will allow development of management strategies that currently do not exist. Funds for this work are derived from University support through Hatch Act and State funds, USDA-ARS research funds, National Potato Council, Frito-Lay Corporation, numerous growers, and state potato commissions.
2. Trade barriers between the US and Canada, and more recently Mexico, have been reduced. Efforts to further open markets in the Far East are continuing. Improved methods of detection and identification of PVY strains have been developed. Funds for this work are derived from University support through Hatch Act and State funds, USDA-ARS, USDA-APHIS, National Potato Council, certified seed growers, state potato commissions.

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