Brief Summary of Minutes of Annual Meeting

WERA-89 Meeting: March 14-15, 2013 New Orleans, LA, Omni Hotel 8:11 am Call to order  Nina Zidack Introductions 2013 attendance list passed around, attached at end of minutes 2012 Minutes: change from 2012, Pablo Guzman wanted to correct that he only heard of Zebra chip in CA, he did not actually see it himself. Minutes moved and seconded and approved. State reports: CO: Kent Sather reported a record aphid year in 2011. CO is seeing influx of seed from Canada, many European varieties and they are worried about influx of PVY-NTN coming in with that. Most states have already been through this and CO seems to be behind the curve, just coming into PVY issues as a major focus and they need to be resolved. ID: Phil Nolte reported that in 2012, rejected seed lots due to PVY went down to 14% as a result of lower aphid pressure and a good hard frost in the fall. Idaho potato seed certification still seems to be a success story  ELISA testing was a positive change. MT: Nina Zidack discussed trends of PVY from 2005-2012 across different varieties. 2012 PVY was up similar to other areas, otherwise no major changes across years. No ZC seen. NE: Steve Marquardt, reported that five percent of lots had PVY in 2011, 6% in 2012. They see Zebra Chip now and then. No major increases or changes in Zebra Chip or other diseases. WI: Alex Crockford reported that 45% of rejections are due to PVY in normal year and 55% due to variety mix and other issues, like paperwork inaccuracies. More PVY-NTN was seen this year, 10% of PVY positives had NTN. Out of state seed to blame for NTN. No other viruses were of major issue. Psyllid monitoring will start in WI; psyllids are in suction traps in Aug  Sept. OR: Jordan Eggers, Oregon State U. reported for Jeff McMoran: number of seed lots up 6% from 2011. WA, Mark Pavek reported that there is an issue with tuber cracking within specialty varieties on West side of WA. Investigation showed a likely correlation between PVY presence and tuber cracking. Commercial seed lot info was handed out indicating PVY incidence and severity has been creeping back up since 2010, but still way below 2004-2008 levels. Leafroll was absent for a second year in the history of the seedlot trial, 2010 being the first  likely due to recent use of neonicitinoid pesticides. END State Reports Conference call with Don Thill: Sequestration comments: NIFA letter outlined some reduction in AFRI, currently funded AFRI projects will continue, 2013 there will be fewer new projects; formula funds will be cut for remaining 5.2% from remaining fiscal year 2013  Hatch etc. which will affect research and extension. Additional Business: Chris Clark (LSU Ag Center): an update on sweet potato diseases. Jonathan Whitworth (USDA-ARS, Aberdeen, ID): reported on his upcoming trip to Kenya. SCRI PVY Reports: Phil Nolte: Effects of PVY on yield in three varieties. Summary: one percent increase in PVY reduces gross returns by $5.13/A to $18.06 per acre for RB, $5.31 to $15.34 per acre for RN. Jonathan Whitworth: PVY national screening trials and ELISA vs. visual results in winter testing trials. 16 cultivars from 8 breeding programs submitted. Tuber ring spot on Yukon Gold is used as control  good expression. MSR and MSN clones from Dave Douches program appeared highly resistant to PVY across sites. Results from other clones varied. Eric Wenninger: Virus-vector interaction studies with different strains and isolates of PVY and different aphid vectors; season colonization of potato by aphid vectors of PVY of Idaho. Green Peach Aphid (GPA) and Potato Aphid (PA) are colonizing species, Bird Cherry Oat Aphid (BCOA) is non-colonizing but because of the high population that moves through potatoes, it can transmit significant proportion of the virus. PVY NTN was transmitted with highest efficiency of the three strains, especially by GPA. Transmission efficiency was greatest by GPA, followed by BCOA and then PA. Seasonal aphid populations appeared near ripening stage of grain (mid to end of July)  potential time to spray grain to prevent movement into potatoes. Russ Groves: SCRI update, applied research to determine when aphids are flying, when and what to spray and which ones are driving disease cycles. They are discovering developmental patterns such as aphids start to move in the west before they do in the east. There are longitudinal and latitudinal differences and they will need to separate this out for recommendations by location. Pamela Hutchinson: Effects of hairy nightshade (HNS) density and size on spread of PVY in potatoes. RN was used as the potato host. It only takes one HNS plant per meter row, from potato emergence to harvest, to reduce tuber yield by >20%. HNS serves as host for PVY and vectors. PVY spread is more efficient between HNS plants then between potato plants. Uncontrolled plants will be large by the time aphids start to fly. Larger HNS plants by week three of testing had higher PVY levels than smaller ones. As density of HNS increases, a trend tends to indicate that PVY infection of HNS plants is more likely compared to less dense plants. Stewart Gray: PVY situation in the US and the reaction of NA cultivars to the various PVY strains. During the 2004-06 survey, PVY-O was the most common. In 2012, we are seeing less O and more PVY NO/NWi and NTN; similar to what happened in Europe in the recent past; which we were able to predict. Shift of strains continues away from PVY-O. Even when aphid picks up PVY-O first, it most likely will transmit PVY-NTN if picked up second. Cultivar differences do exist. Goal is to have major cultivars shown healthy and with symptoms of PVY strains. Strain shift is happening because hybrid recombinants have a fitness advantage, cultivar development has promoted tolerant selections, visual assessment for viruses in cert programs has not worked very well for these, and regulatory policies were not as stringent as necessary. Alex Karasev: Typing of PVY strains via WA State U Seed Lot Trial. Plants within the WSU seed lot trial with visual mosaic/PVY symptoms were sampled. Eighty nine and eighty five percent of samples visually identified in 2011 and 2012, respectively, tested positive for PVY in lab. Reading error, PVS, PVA, herbicide, and nutritional issues may account for the ones that did not test positive. PVY-O infected 63% and PVY-N:O 27% of positive plants in 2011; during 2012 PVY-O infected 32% with 40% infected with N:O. PVY-NTN and NA-N increased from 2011 by 10% overall. NTN isolates, associated with PTNRD, can be found in seed systems of most states; overall incidence of NTN isolates tends to increase; N-Wi isolates seem to be displacing PVY O in all states. A novel approach of PVY strain differentiation. A new set of primers for better typing of PVY strains is described based on nucleotide polymorphism around main recombinant junctions. Adjourn until Friday March 15, 2013. March 15, call to order: 8:10 am Jordan Eggers: Tubers storage ZC ratings, screen house study and volunteer survey studies. Report of 2011: first foliar symptoms seen in mid-July (via infrared), 1st psyllids observed in August but may have been there earlier, based on difficulty of trapping low numbers. High infection rates due to no insecticide during infectious periods. Question after 2011 was what was going to happen with the volunteer potato plants and are they important in the spread of ZC? Many volunteer plants found. Of the plants collected, only 48.6% of Rangers and 53.3% of Umatilla plants with symptoms actually tested positive. Projection of Lso-infected volunteers was 491 plants/A in Ranger field and 607 plants/A in Umatilla field. Screen house study with Alturas, RN, Ranger, Umatilla, and RB to observe growth and survival patterns after previous year infection. Emergence was greater than expected; most had stunted growth and again, the large terminal leaf. 53% sprouted and produced plants; the control treatment was 99%, 10.3% showed symptoms, 58% of plants with symptoms tested positive for Lso-infection. Symptomatic plants emerged more rapidly than control plants, had fewer sprouts, shorter vines, died earlier (45 days of survival for infected plants, 92 days for healthy plants). Z Chip symptom incidence and severity (in seed) were significant predictors of % emergence. They found that volunteer potatoes can be a source of Z Chip spread. In 2012, ZC incidence was below 1% due to very few volunteers likely due to poor emergence. Herbicides can be used to reduce volunteer number, psyllid populations are not present in large numbers until after volunteers die naturally, psyllids apparently came in high numbers in selected areas in 2011 (didnt seem to happen in 2012), psyllids overwinter in the area but have not been problems in the past (no significant psyllid yellows). They believe that a single TIMELY and effective insecticide application to pivots nearby the hardest hit areas in 2011 effectively and significantly reduced ZC infection. Conclusion: volunteers are not likely to be an important source of ZC, particularly when reasonable control of potato psyllids occurred in the previous and present year. Jorge Abad: a few years ago they detected a virus from S America in true potato seed. Negative for every test they have in their lab. Deep sequencing indicated a caulimovirus. Nina Zidack: Comparison of methods for detection of PVY (PCR better detection than ELISA) and PVA (PCR and ELISA similar in results). Observations on varietal incidence of PVA in the field and after artificial inoculation: PVA is a potyvirus, non-persistent aphid transmission, causes yield loss in RB, small yield impact to RN. Prior to 2007 ID and OR started to require PVA is included in total mosaic tolerances for seed lots to be re-certified. MT started in 2007. G1 and G2 seed did not show much PVA compared with G3 seed prior to 2012. They have successfully reduced PVA via testing and rouging. RB appears the most susceptible of the common varieties, Norkotah second; was rarely seen in Classic, DRN, Umatilla, and Ranger. Shepody likely susceptible but they have very few lots in the state. Week 1 after inoculation, real time PCR detected some PVA but ELISA did not. Week 4 both PCR and ELISA were similar. Visual inspections are inadequate for viruses you cannot see, tissue sampling and testing is necessary. Collectively, MT growers may be spending over $12,000 per year to test for PVA. Jim Crosslin: Potato Moptop Virus (PMTV) susceptibility in cultivars and breeding lines. Sixty two clones planted into 5 hill plots in Grant County, Washington. ELISA worked very well to detect PMTV. Only one clone, POR06V12-3, showed 0 infection within the Non-symptomatic tubers; this clone also had a low percent (3%) of symptomatic tubers. This clone was bred to have PVY resistance, so maybe a link in genetics (?). On the other side of the spectrum, Alpine Russet had 90% infection within symptomatic tubers, RB was at 60%. When symptoms were observed, roughly 70% of the time those symptoms were caused by PMTV. Many clones had high numbers of symptomless tubers that tested positive for PMTV  this is a large concern for processors. Included in this group were RB, Ranger, Umatilla, Alturas, RN, Alpine Russet and many new clones that have not yet been released to the public. Jims first investigation and identification of PMTV in WA was in 2007 after a shipment was stopped at the Mexican border due to PMTV detection. PMTV appears to be more common across the US than once thought (comment by a participant during discussion). Election of Secretary: Mark Pavek nominated Carrie Wohleb as Secretary for 2014; approval via vote was unanimous. Plans for 2014 meeting: Date: Location: similar week in March 2014. Santa Fe, NM or San Diego. Phil Nolte moved to adjourn at 10:50 am Adjourn

PVY: A novel methodology to type PVY strains has been introduced, allowing researchers to distinguish up to nine distinct genotypes of the virus. This technique is based on multiplex RT-PCR technology probing several recombinant junctions in PVY genome. PVA: Six years of field testing demonstrated that 100% summer leaf sampling for PVA and roguing of positives in Nuclear and Generation 1 seed potatoes reduced PVA incidence from 15% of PVA infected seedlots in 2007 down to 1.5% of seedlots in the 2012 post harvest test. Summer testing revealed that by far the most susceptible varieties to PVA are Russet Burbank and Russet Norkotah. This observation was backed up by data in greenhouse trials where 10 varieties of potatoes were mechanically inoculated with PVA and leaf samples were analyzed using ELISA and PCR 1 and 4 weeks after inoculation. 4 weeks after inoculation, Russet Burbank and Russet Norkotah showed 70% infection, Dark Red Norland was 30% infected and Classic was 10% infected. Alturas, Amisk, Ranger, Umatilla and Yukon Gold had no detectable virus using Quantitative RT-PCR. If PVA becomes a problem in a specific area, certification labs can use summer leaf testing to identify PVA infected plants for roguing, even when the symptoms are too mild to visualize. PVA resistant varieties can be planted as borders around more susceptible varieties to reduce transmission of PVA to early generations. Potato mop-top virus (PMTV): Demonstrated that infections with Potato mop-top virus (PMTV) frequently do not produce visible symptoms in infected tubers of many potato cultivars. Zebra Chip (ZC): Demonstrated that common potato cultivars grown in the Columbia Basin that are infected with C. Liberibacter solanacearum can produce infected tubers that sprout and grow into infected plants. This can happen in either potato volunteer or potato seed situations. We also showed that these seed borne infections are not likely to be sources of the bacterium for current season spread by potato psyllids due to a number of factors related to when the vector occurs in significant numbers, environmental conditions that normally do not favor the vector, the low number of infected plants that arise from infected tubers, and crop plants that hide infected plants from the vector. Despite previous findings, the team discovered that Zebra Chip does display tuber symptoms and can spread through the seed system. Potatoes that overwinter in the soil and emerge as volunteers the next spring can contain Candidatus Liberibacter and may serve as a source for current-season infection of commercial fields. It was found that ZC spreading psyllids can and do overwinter in ID, OR, and WA Weeds have been found to harbor psyllids which spread ZC; some may be host of Lsoinfection.

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