Source: WASHINGTON STATE UNIVERSITY submitted to NRP
INTEGRATED ONION PEST AND DISEASE MANAGEMENT
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
COMPLETE
Funding Source
HATCH
Reporting Frequency
Annual
Accession No.
1014550
Grant No.
(N/A)
Cumulative Award Amt.
(N/A)
Proposal No.
(N/A)
Multistate No.
W-3008
Project Start Date
Nov 8, 2017
Project End Date
Sep 30, 2022
Grant Year
(N/A)
Program Code
[(N/A)]- (N/A)
Recipient Organization
WASHINGTON STATE UNIVERSITY
240 FRENCH ADMINISTRATION BLDG
PULLMAN,WA 99164-0001
Performing Department
Plant Pathology
Non Technical Summary
Onion, Allium cepa, is the third most consumed vegetable in the US, behind tomato and potato. The per capita consumption of onion in the US is about 20 pounds per year, which has increased 70% over the past 20 years (https://www.onions-usa.org/all-about-onions/consumption). Onion is also one of the most economically important specialty crops with a farm-gate value of nearly $1 billion per year (https://www.nass.usda.gov/Publications/Ag_Statistics/2015/Chapter04.pdf) and over $70 million in added value after processing. In addition, over 20% of the world's onion seed is produced in the US and is valued at over $100 million per year. Onion is grown on 125,000 acres across at least 20 states with a majority produced in California, Idaho-Eastern Oregon and Washington in the west, and Georgia and New York in the east (https://www.onions-usa.org/all-about-onions/where-how-onions-are-grown).Onion crops are damaged by a similar spectrum of pests and pathogens throughout the US. For example, onion thrips, Thrips tabaci, damages onion plants by feeding on leaves. The damage can reduce onion bulb yield and quality by up to 30 to 50% (Fournier et al. 1995). Onion thrips also is notorious for developing resistance to insecticides (Shelton et al. 2003, 2006; McIntyre Allen et al. 2005) and spreading pathogens like Iris yellow spot virus (IYSV, which causes Iris yellow spot disease [IYS]) that also can reduce bulb yield and quality as well as seed production (Gent et al. 2004, 2006; du Toit and Pelter 2005; Bag et al. 2015). Multiple fungal and bacterial pathogens can cause onion yield losses in the field and in storage facilities throughout the U.S. (Schwartz and Mohan 2008). Each disease can cause up to 25 to 100% crop loss. The most important fungal diseases include Stemphylium leaf blight (caused by Stemphylium vesicarium), purple blotch (Alternaria porri), downy mildew (Peronospora destructor), black mold (Aspergillis niger), Botrytis leaf blight (Botrytis squamosa) and neck rot (Botrytis species), powdery mildew (Leveillula taurica), Fusarium basal rot (Fusarium oxysporum f. sp. cepae) and white rot (Sclerotium cepivorum). The most important bacterial diseases include sour skin (Burkholderia cepacia), slippery skin (Burkholderia gladioli pv. Alliicola), center rot (Pantoea ananatis and P. agglomerans), leaf streak (Pseudomonas viridiflava), soft rot (Pectobacterium carotovorum and Dickeya spp.), and Enterobacter bulb decay (Enterobacter cloacae). Growers continue to abandon onion production in some regions because one or more of these organisms have caused catastrophic losses. Consequently, they have identified these pathogens and pest as major threats to the sustainability of their industry (http://www.ipmcenters.org/pmsp/pdf/USonionPMSP.pdf). This project proposes to address these concerns through four objectives:Evaluate onion germplasm for resistance to pathogens and insects.Investigate the biology, ecology and management of onion thrips and other pests.Investigate the biology, epidemiology and management of onion plant pathogens.Facilitate discussions between W3008 participants and onion industry stakeholders that will advance onion pest and disease management.The work proposed is critical for solving the important pest and disease problems facing the US onion industry. We are not aware of other public or private entities that will be as organized across state borders to solve these problems as the W3008 group, particularly given the successful foundation set by the preceding multistate projects (W1008: Biology and Management of Iris yellow spot virus (IYSV) and Thrips in Onions from 2005-2010, and W2008: Biology and Management of Iris yellow spot virus (IYSV), Other Diseases and Thrips in Onions from 2011-2016). We anticipate that results from this research and extension effort will continue to contribute significantly to science and agriculture as we communicate new knowledge about the biology, ecology and management of these pests and pathogens through peer-reviewed publications, presentations at professional meetings, field days, and web-based resources for stakeholders. Consequences of not addressing these significant issues include further reductions in US onion acreage due to limited ability to manage the pest and diseases mentioned above, reduced profits as a result of decreased bulb yields, reduced quantities and/or qualities of onion seed produced, and greater pesticide and fertilizer inputs, as well as potential environmental and human health concerns associated with greater fertilizer and pesticide use.
Animal Health Component
50%
Research Effort Categories
Basic
25%
Applied
50%
Developmental
25%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
2111451110115%
2111451113015%
2121451110210%
2121451110010%
2161451106015%
2165220106015%
2111451108110%
2121451108110%
Knowledge Area
212 - Pathogens and Nematodes Affecting Plants; 211 - Insects, Mites, and Other Arthropods Affecting Plants; 216 - Integrated Pest Management Systems;

Subject Of Investigation
1451 - Onion, garlic, leek, shallot; 5220 - Pesticides;

Field Of Science
1060 - Biology (whole systems); 1101 - Virology; 1130 - Entomology and acarology; 1081 - Breeding; 1100 - Bacteriology; 1102 - Mycology;
Goals / Objectives
Evaluate onion germplasm for resistance to pathogens and insects. Investigate the biology, ecology and management of onion thrips and other pests. Investigate the biology, epidemiology and management of onion plant pathogens. Facilitate discussions between W3008 participants and onion industry stakeholders that will advance onion pest and disease management.
Project Methods
Objective 1: Evaluate onion germplasm for resistance to pathogens and insects. Onion breeding research will be conducted and/or evaluated during this project in New Mexico, New York, Oregon, Washington and Wisconsin. We will evaluate responses of onion entries (advanced breeding lines, cultivars, germplasm accessions) to IYSV and onion thrips populations under field and controlled conditions at cooperating sites with different environmental conditions. Additional screening and identification of promising materials will continue to be promoted for use in onion cultivar improvement efforts by public and private onion breeders at cooperating sites throughout the US. If related funding is procured, onion germplasm screening for resistance to other pests/diseases will also take place, e.g., to bacterial and fungal pathogens of importance in the Pacific Northwest USA, like slippery skin and Fusarium basal rot.Objective 2. Investigate the biology, ecology and management of onion thrips and other pests. Research efforts will focus primarily on improving our knowledge about onion thrips biology, ecology and management. However, the biology and management of other pests like onion maggot, seedcorn maggot, etc. will be addressed based on regional growers' priorities. Research is needed to determine if onion thrips populations have developed resistance to commonly used insecticides like spinetoram (Radiant SC). Another project will concentrate on understanding dispersal of viruliferous onion thrips among onion bulb and seed crops. In Washington State, onion bulb and seed crops often are grown in close proximity, creating a perennial host for both thrips and IYSV. The dispersal of thrips in time and space as well as the epidemiology of IYSV where bulb and seed plantings co-occur is not well known. Likewise, the role of other "green bridge" hosts in thrips population dynamics and IYSV epidemiology is poorly understood. Densities of thrips will be monitored during the year using sticky cards and visual counts of thrips on plants, while IYSV in onions will be ascertained using PCR assays. Subsamples of thrips also will be tested for IYSV using PCR assays to help identify dispersal patterns. Management of onion thrips will continue to be evaluated using new insecticides, insecticide use patterns and alternative delivery systems. For example, efficacy of new insecticides like Minecto Pro (abamectin + cyantraniliprole) will be evaluated in small-plot field trials. Insertion of Minecto Pro and other new products into season-long insecticide programs will be evaluated, including using action thresholds. Compatibility of optimal, season-long insecticide sequence programs with other pesticides, especially fungicides, also will be evaluated in field experiments. In the western US, onions are irrigated primarily via center pivot or drip irrigation, and insecticides typically are applied either as foliar sprays or via chemigation. Management of thrips using insecticides applied by sprinkler and drip chemigation will be compared with standard foliar applications. Understanding the most effective application methods will help producers customize and optimize insecticide programs.Objective 3. Investigate the biology, epidemiology and management of onion plant pathogens. Iris yellow spot virus. IYSV continues to be a major pathogen of importance in onion production regions in the western and northeastern US. Efforts will continue to focus on understanding the molecular epidemiology and evolution of IYSV. Using a whole genome sequencing approach, molecular characterization and genetic diversity studies of IYSV populations from the Pacific Northwest will be conducted, led by Pappu's group, and comparative analyses carried out globally to better understand factors that might contribute to the diversity and evolution of IYSV. Interactions between IYSV and onion at the transcriptome level will be carried out using next generation sequencing. Using the complete IYSV genomic sequence as a reference, virus-specific small RNA profiles will be determined from cultivars susceptible and those with tolerance to IYSV. The profiles will help identify regulatory pathways potentially affected by IYSV infection, and could lead to development of molecular markers associated with virus resistance/tolerance. Fungal pathogens. In the Pacific Northwest, research will continue on the potential use of arbuscular mycorrhizal fungi inoculants in direct-seeded and transplanted onion bulb crops for enhancing onion production by increasing phosphorus use efficiency, reducing the severity of onion soilborne pathogens (particularly those causing root diseases), and promoting vigorous growth of onion plants. The impact of soil fertility levels, particularly phosphorus, on the potential benefits of mycorrhizal inoculants will be evaluated on controlled greenhouse trials and in grower-cooperator field trials under different irrigation systems to assess the importance of growers' modifying fertilizer practices in order to benefit from using mycorrhizal inoculants. Bacterial pathogens. Management of bacterial pathogens requires an integrated approach that focuses on understanding the potential sources of bacteria (seed, transplants, soil, weeds and crop debris), their etiology and epidemiology, as well the impact of combinations of management practices to reduce losses. Research will be continued in the semi-arid Pacific Northwest on understanding the cause(s) and management of internal dry scale and associated fungal and bacterial bulb rots that have been particularly prevalent and severe in years with periods of extreme heat stress mid-summer. Field trials on irrigation management will be carried out to assess potential alleviation of this physiological disorder using this cultural practice, along with evaluations of the timing and rates of applications of bactericides (coppers, disinfectants) and fungicides for management fungal and bacterial bulb rots.Objective 4. Facilitate discussions between W3008 participants and onion industry stakeholders that will advance onion pest and disease management. Participants from all states on this project will be involved. We intend to expand membership in W3008 by broadening the scope of the objectives and connecting with more stakeholders in the national onion industry. A concerted effort will be made to inform the onion industry about upcoming W3008 annual meetings via trade magazines, email, internet promotions, and a new and improved version of the www.alliumnet.com web site.Annual meetings for W3008 will be held to share information, update participants on current research and extension efforts, identify sources of support for research and extension needs, and establish cooperative approaches to research and extension projects. When possible, we will schedule annual W3008 meetings in conjunction with NARC and NOA. Participation at meetings will be encouraged from all organizations, regions and countries. Prior to each annual meeting, individual or smaller groups of participants will engage stakeholders about research and extension results at local and regional meetings, including field days and twilight meetings. Research results will be published in refereed and non-refereed journals, extension bulletins, the trade magazine Onion World, and posted on the web sites of individual programs or institutions or other outlets.

Progress 10/01/19 to 09/30/20

Outputs
Target Audience:Onion researchers, Extension specialists, graduate students, interns, postdoctorates, growers, consultants, packers, and other stakeholders. Changes/Problems:Some research progress was constrained in spring/summer 2020 following the outbreak of the COVID-19 pandemic. Research plans have been adjusted accordingly. What opportunities for training and professional development has the project provided?The 'Stop the Rot' onion SCRI team met for 2 days at the Univ. of GA in Feb. 2020 for orientation to the whole project and to plan the 1st of the 3 field seasons of the project. The meeting included a hands-on lab session to review basic methods to be used for the 12-state survey of onion bulb crops for bacterial diseases. Workshop was attended by 25 team members, including faculty, technical staff, postdoctorates, graduate students, and some of the Stakeholder Advisory Panel members. How have the results been disseminated to communities of interest?Refer to the various outputs, publications, videos, websites, and presentations at grower meetings listed in the Products/Serices section. The 2020 WSU Onion Field Day was canceled because of the COVID-19 pandemic constraints. What do you plan to do during the next reporting period to accomplish the goals?Follow the proposal plans for Season 2 of the SCRI Stop the Rot project, including monthly team meetings for planning and problem solving.

Impacts
What was accomplished under these goals? Objective 1. The Washington State University Onion Cultivar Trial was planted in April 2020 near Pasco, WA, with three replicate plots of each of 51 cultivars submitted by various onion seed companies. The plots were evaluated regularly for diseases and pests. Bulbs were harvested from the plots in September to assess yield, and 50 bulbs/plot were placed in storage to evaluate for storage quality and storage rots in February 2021. Objective 2. Several insecticide efficacy trials were conducted to evaluate control options for onion thrips (Thrips tabaci) management. One trial featured new unregistered insecticides, one of which was nearly as efficacious as Radiant (spinetoram), which is currently the most effective insecticide available for use by producers. Another trial looked at products that are currently registered for use on onions, but that are not used to manage onion thrips. None of those insecticides provided consistent efficacy that compares to products that are currently already in use. In collaboration with Dr. Doug Walsh, we also evaluated insecticide resistance in onion thrips found in commercial fields. We tested for resistance to Radiant (spinetoram), Movento (spirotetremat), and Torac (tolfenpyrad). Results are still being evaluated, but the assays appeared to not be working this season. We will need to reevaluate the methods we use for coming seasons to monitor for the development of resistance to commonly used insecticides. Alternative insecticides were also tested for control of seed corn maggot (Delia platura). Pest pressure was lower than anticipated and as such, we did not detect any differences among the insecticides screened. This project will be repeated in 2021. The genetic diversity of onion thrips (Thrips tabaci) in various onion-growing regions of the US is being determined. The 658 bp fragment of the COI-5? was used to carry out barcoding. Haplotypes were generated using sequence polymorphism software (DnaSP 5.10). A total of 15 T. tabaci samples from eight locations (four states) were analyzed. Two T. tabaci haplotypes with haplotype diversity of 0.740 ± 0.030 and 14 polymorphic sites (SNPs) were found. Haplotype 1 was the most common haplotype. Objective 3. In Oct. 2019, metam sodium soil fumigation trials were set up in the Columbia Basin to assess the efficacy of 4 methods of application of Sectagon (chemigated at 40 gpa, shanked at 10" depth at 40 gpa, shanked at 4 and 10" depths at a total 40 gpa, and chemigated at 20 gpa + shanked at 10" depth at 20 gpa) compared to non-fumigated control plots for control of stubby root nematode, weeds, Fusarium basal rot, and pink root in onion bulb crops. One trial was in a grower's field near Othello that had a high population of stubby root nematode, and the other trial was in a field near Pasco that had high populations of the pink root pathogen. In the Pasco trial, most metam sodium was at the 4" depth in chemigated plots, whereas shank applications distributed metam sodium more evenly from 6 to 10" deep. More metam sodium was detected in plots with shank applications compared to plots with chemigation. At the Othello trial, soil moisture was ~80% saturation during fumigation, closer to the recommended soil moisture for effective fumigation than the 50% at the Pasco trial during fumigation. Metam sodium levels in plots with chemigated + shanked applications were at least 4x greater in the Othello trial than the Pasco trial. This showed the importance of adequate soil moisture during fumigation with metam sodium to increase efficacy of applications, particularly by chemigation. Soilborne inoculum of S. terrestris in fall 2019, prior to applying Sectagon 42, averaged 11.6 CFU/g in the Othello trial and 6.9 CFU/g in the Pasco trial. In both trials there was a significant decline in soilborne inoculum by spring of 2020, regardless of fumigation treatment. Compared to non-fumigated plots, none of the methods of applying Sectagon 42 reduced inoculum of S. terrestris, and none reduced the incidence of bulbs with pink root or severity of pink root. Similarly, none of the methods of applying Sectagon 42 reduced the incidence of bulbs with Fusarium basal rot or severity of Fusarium basal rot. In Othello, no treatment reduced broadleaf weed pressure compared to non-fumigated plots. Plots shanked with Sectagon 42 at 10" or at 4" + 10" depths had fewer broadleaf weeds than chemigated plots. Chemigation + shanking did not improve weed control compared to shanking alone in Pasco. Very low populations of stubby root nematode were detected in pre-fumigation soil samples at Othello. Root lesion nematodes were too low to be damaging, and similarly for root knot, stunt, and pin nematodes. In June 2020, distinct patches of stunted plants were observed in the Othello field, from stubby root and lesion. The irregular distribution of patches made it difficult to assess efficacy of fumigation treatments, but there was no evidence that any method of Sectagon 42 application provided nematode control. Few plant parasitic nematodes were detected in the Pasco trial. The results suggested very limited or no efficacy of the chemigated and shanked applications of Sectagon 42 for control of weeds, pink root, Fusarium basal rot, and nematodes under the conditions of these trials. Research was initiated in fall 2019 on the project 'Stop the rot: Combating onion bacterial diseases with pathogenomic tools and enhanced management strategies' funded by the USDA NIFA Specialty Crops Research Initiative (SCRI) in May 2019. The proposal was funded at $4.0 million with matching funding of $4.2 million. In 2020, 5 onion bulb crops were each surveyed twice for symptoms of bacterial diseases. Isolations yielded >300 bacterial strains being identified using DNA sequencing, and tested for pathogenicity on onions. This is part of a 12-state survey of onion bulb crops in 2020. Strains will be part of the National Onion Bacterial Strain Collection. Nine onion field trials were set up in WA in 2020: 1) bactericide trial, 2) cultivar screening trial, 3) postharvest bulb treatments, 4) timing of topping onion bulbs, 5) undercutting onion bulbs, 6) rolling onion tops before harvest, 7) nitrogen fertilizer program, 8) frequency of irrigation, and 9) timing of terminating irrigation. Bulbs from the trials are in storage to be evaluated for bacterial rots. Objective 4. Newsletter articles were written and distributed to >600 subscribers, mostly in the Pacific Northwest USA, via WSU Onion Alerts.

Publications

  • Type: Book Chapters Status: Accepted Year Published: 2020 Citation: Resende, R., A.E. Whitfield, and H.R. Pappu. 2020. Orthotospoviruses (Tospoviridae). Encyclopedia of Virology. 4th edition. Elsevier Press. In press.
  • Type: Journal Articles Status: Published Year Published: 2020 Citation: du Toit, L.J., Derie, M.L., Holmes, B.J., Winkler, L.R., Waters, T.D., and Darner, J. 2020. Effects of an arbuscular mycorrhizal fungal inoculant and a mycorrhizal stimulant on pink root and productivity of dehydration onion crops near Paterson, WA, 2016. Plant Disease Management Reports 14:V062.
  • Type: Other Status: Published Year Published: 2020 Citation: du Toit, L.J., Waters, T., Derie, M., and Darner, J. 2020. Battling onion bacterial diseases with bactericides. Onion World, Dec. 2020:6-11.
  • Type: Other Status: Published Year Published: 2020 Citation: Hoepting, C., and du Toit, L. 2020. Stop the Rot! National U.S. team to combat bacterial diseases of onion with fierce collaboration. Onion World, July/August 2020:8-11.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: du Toit, L.J. 2020. Onion bacterial diseases: Knowledge gaps and a federal grant to Stop the Rot. Invited presentation, 2020 Grower Education Conference & Industry Show, Wisconsin Potato & Vegetable Growers Association & University of Wisconsin Division of Extension, 4-6 Feb. 2020, Stevens Point, WI. Zoom videoconference (~20 people)
  • Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: du Toit, L.J. 2020. Onion fungal and bacterial bulb rots, and efficacious use of fungicides for disease control in onion production. Invited presentation, AgriNorthWest farm managers, 5 Feb. 2020, Kennewick, WA (50 people)
  • Type: Journal Articles Status: Published Year Published: 2020 Citation: du Toit, L.J., Brouwer, L.R., Derie, M.L., Henrichs, B.A., Holmes, B.J., and Waters, T.D. 2020. The effect of formulation and application method of commercial arbuscular mycorrhizal fungi inoculants on onion seedlings in a growth chamber study, 2016. Plant Disease Management Reports 14:V059.
  • Type: Journal Articles Status: Published Year Published: 2020 Citation: du Toit, L.J., Derie, M.L., Holmes, B.J., Miller, C.E., Brouwer, L.R., Waters, T.D., and Darner, J. 2020. Effects of three arbuscular mycorrhizal fungi inoculants on pink root and yield in a commercial onion bulb crop near Othello, WA, 2017. Plant Disease Management Reports 14:V061.
  • Type: Journal Articles Status: Published Year Published: 2020 Citation: du Toit, L.J., Derie, M.L., Holmes, B.J., Miller, C.E., Morgan, P., Brouwer, L.R., Waters, T.D., and Darner, J. 2020. Effects of Mykos Gold Granular, an arbuscular mycorrhizal fungi inoculant, on pink root, white rot, and crop growth in spring- and fall-planted sweet onion crops near Walla Walla, WA, 2017-2018. Plant Disease Management Reports 14:V060.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: du Toit, L.J. 2020. Effective identification and management of diseases impacting vegetable crops. Invited presentation, Columbia Basin Crop Consultants Association Short Course, 29-30 Jan. 2020, Moses Lake, WA. (~100 people)
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: du Toit, L.J. 2019. Bacterial rots of onion: USDA SCRI project update and knowledge gaps. Pacific Northwest Vegetable Assoc. Annual Convention & Trade Show, 20-21 Nov. 2019, Kennewick, WA. (200 people)
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: du Toit, L.J. 2019. Effective identification and treatment of diseases impacting onion. Pacific Northwest Vegetable Assoc. Annual Convention & Trade Show, 20-21 Nov. 2019, Kennewick, WA. (200 people)
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: du Toit, L.J. 2019. Keeping our seed pathogen-free. Webinar presented at BC Seed Gathering 2019, Kwantlen Polytechnic University, 9 Nov. 2019, Richmond, BC. YouTube recording https://www.youtube.com/watch?v=DNub-iJXbHo&t=1s (20 people in person + online attendance)
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Waters, T.D., and Reitz, S. 2019. Avoiding further resistance development and insecticide efficacy for onion thrips. Pacific Northwest Vegetable Association, Kennewick, WA. Invited. (200 people)
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Waters, T.D. 2019. Seedcorn maggot biology and control in organic production systems. Pacific Northwest Vegetable Association, Kennewick, WA. Invited. (200 people)
  • Type: Other Status: Published Year Published: 2020 Citation: WSU Onion Alerts (https://mailchi.mp/wsu/wsu-onion-alert-aug-14-1303793?e=72ba613792): Time-sensitive onion disease, pest, and production topics covered in regular articles between May and August of 2020.
  • Type: Websites Status: Published Year Published: 2020 Citation: https://alliumnet.com/projects/stop-the-rot/ website added and updated regularly to include outline and progress on the USDA NIFA SCRI 'Stop the Rot' onion bacterial disease project.
  • Type: Websites Status: Published Year Published: 2020 Citation: Pacific Northwest Vegetable Extension Group (PNW VEG) website (http://mtvernon.wsu.edu/path_team/vegpath_team.htm), a tri-state Extension team with resources on diverse vegetables grown in the PNW USA. Sections on onions include the Photo Gallery (http://mtvernon.wsu.edu/path_team/onion.htm) and IPM Resources (http://mtvernon.wsu.edu/path_team/ipmResources.htm#onion).


Progress 10/01/18 to 09/30/19

Outputs
Target Audience:Onion growers, consultants, agronomists, breeders, researchers, extension specialists, packers, shippers, graduate and undergraduate students, postdoctoral research scientists. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Postdoctoral research scientists, graduate and undergraduate students, and interns worked in du Toit, Waters, and Pappu's program on onion projects that fall under this W-3008 project. How have the results been disseminated to communities of interest?Refer to the list of papers and publications from this project. Numerous presentations were given at an onion field day in WA, and at stakeholder meetings in Washington State, the greater PNW, nationally, and internationally. Timely articles related to onion production issues were shared at least monthly through the growing season on the WSU Onion Alert. Onion resources were also shared on the PNW VEG website. Samples were diagnosed and relevant recommendations made to growers, consultants, field reps, etc. through the season. What do you plan to do during the next reporting period to accomplish the goals?Collaborative efforts and networking of W-3008 members led to successful submission and funding of a $4.0 million + $4.2 million matching funding, 4-year USDA NIFA SCRI grant to help onion stakeholders address the negative impacts of bacterial diseases on onion production in the USA. The project was ranked highly by the review panel, particularly the well-established national network of collaboration among 24 onion researchers and extension specialists with growers and other onion stakeholders across the USA. This productive collaboration has resulted, in part, from the many years of synergistic interactions through the W-1008, W-2008, and now the W-3008. In 2020, we will get the USDA NIFA SCRI 'Stop the Rot' bacterial project going fully with 13 institutions and 24 collaborators. The team will meet twice a year, including with the 12-member Stakeholder Advisory Panel.

Impacts
What was accomplished under these goals? Objective 1. Evaluate onion germplasm for resistance to pathogens and insects. The WSU University Onion Cultivar Trial was planted in May 2019 near Connell, WA, with three replicate plots of each of 47 cultivars submitted by onion seed companies. Plots were evaluated for diseases and pests. In August, plots were rated for percentage tops down and severity of powdery mildew, a disease not often seen in the Columbia Basin but which showed up more than normal during 2019 with significant differences among cultivars. Bulbs were harvested from plots in September to assess yield, and 50 bulbs/plot placed in storage to evaluate for storage quality and rots in February 2020. Several cultivars and breeding lines were evaluated for response to IYSV infection under field conditions. Symptom severity, final disease incidence and relative virus levels are used to identify cultivars with resistance or tolerance. Objective 2. Investigate the biology, ecology and management of onion thrips and other pests. The pest management strategy for most commercial onion farms focuses on application of different chemistries of insecticides to reduce onion thrips infestation. Previous study by Walsh at WSU IAREC documented universal incidence of resistance to pyrethroids among onion thrips populations in Washington. The source of resistance is mutations in the voltage-gated sodium channel, the target site of pyrethroids such as lambda-cyhalothrin. Another class of insecticide commonly used for thrips control in onions is the carbamates, i.e., oxamyl (Vydate) and methomyl (Lannate LV), which are often applied multiple times to fields over the growing season, and both have been used for over 25 years. Due to regulatory and environmental issues, the rate of development of insecticide resistance typically far outpaces discovery and registration of new chemistries/products. Insecticide resistance monitoring was done in commercial fields in Washington. We evaluated tolerance of onion thrips to field doses of oxamyl and methomyl. Commercial fields with a history of oxamyl and methomyl use contained thrips populations far less susceptible to those insecticides than thrips from fields where these insecticides had not been used. This demonstrated resistance is present in thrips populations in the Columbia Basin of Washington. We confirmed again that when seedcorn maggot is present in a field, seed treatments can increase plant stand and yield and quality of onion crops. Commercial producers are aware of this technology and adoption is widespread. In conventional crops, 4 active ingredients (dpinetoram, methomyl, abamectin, and cyantraniliprole) were highly effective, and one (spirotetremat) is somewhat effective. Producers need better information on timing and appropriate sequences of application. Organic producers still have limited options. Spinosad has been shown to be effective, and efficacy is enhanced with two tank mix partners (azadiractin and a Burkolderia sp.). Additionally, we determined that three organic products applied alone were ineffective for thrips control (Celite, Venerate, and AzaDirect). Objective 3. Investigate the biology, epidemiology and management of onion plant pathogens. A field trial funded by the IR-4 Minor Crops program was planted in Pasco, WA in spring 2019 to evaluate efficacy of 14 treatments (products) for control of bacterial leaf blight and bulb rots caused by Burkholderia gladioli pv. alliicola and Pantoea agglomerans, using a RCBD with four replicate plots/treatment. Products applied to main plots (2 beds wide) included ManKocide, Kocide 3000-O, Champ WG, Oxidate 2.0, Kasumin 2L (at 2 rates), Nano-magnesium oxide, GWN 10120, SP8010 (alone with tank-mixed with Kocide 3000-O or SP2700), Lifeguard WG, and Instill. Each product was applied 3-7 times at weekly or 5-day intervals, depending on label restrictions. Split plots (1 bed x 15 feet) were either inoculated twice with the bacterial pathogens or not inoculated (water). Plots were rated weekly for incidence and severity of foliar symptoms. Bulbs were harvested in September, with 25 bulbs cut and rated for bacterial rots and another 25 bulbs placed in storage for evaluation in February 2020. Inoculation with the two pathogens very successfully caused bacterial leaf blight and bulb rot. Inoculated plots averaged 63% incidence of bulb rot vs. 23% for non-inoculated plots, reduced the number of marketable bulbs from 37 to 34/plot, and reduced marketable bulb weight from 46 to 39 tons/acre. The only products that reduced incidence of bulb rot and increased marketable yield were Kocide 3000-O and Lifeguard. In fall 2019, metam sodium soil fumigation trials were set up in the Columbia Basin to assess the efficacy of 4 methods of application (chemigated, shanked at 10", shanked at 4 and 10", and chemigated + shanked) in Sep.-Oct. for control of stubby root nematode, weeds, Fusarium basal rot, and pink root. One trial was set up in a grower's field near Othello that had a high population of stubby root nematode, and another in a grower's field near Pasco that had high populations of the pink root pathogen. Each trial had 4 replications of 5 treatments. Seventy soil cores in a grid in each plot (2" spacing to a depth of 12" x 10 cores wide) were tested to assess location and amount of fumigant. Prior to fumigant application, soil cores were collection from each plot. A subsample/plot was used to quantify the pink root pathogen, a subsample was sent to identify and quantify nematodes in each plot, and a subsample was plated on Komada's agar medium to quantify Fusarium oxysporum. These pre-fumigation levels of pathogens/pests in each plot will be compared to levels detected in soil sampled from each plot in spring 2020 at onion planting to monitor post-fumigation changes in pathogens/pests. Onions will be assessed for impacts of fumigation on weeds and diseases. Objective 4. Facilitate discussions between W3008 participants and onion industry stakeholders that will advance onion pest and disease management. Newsletter articles were written and distributed to >600 subscribers, mostly in the Pacific Northwest USA, via the WSU Onion Alerts (https://mailchi.mp/wsu/wsu-onion-alert-aug-14-1303793?e=72ba613792). Time-sensitive topics covered in seven articles between May 30 and August 21 of 2019 included downy mildew, fungicides, thrips, nematodes, iris yellow spot, irrigation, and powdery mildew. A grant proposal titled 'Stop the rot: Combating onion bacterial diseases with pathogenomic tools and enhanced management strategies' was submitted to the USDA NIFA Specialty Crops Research Initiative (SCRI) in May 2019. The proposal was led by Lindsey du Toit from WSU, with 5 co-PIs, 18 other collaborators from 12 states in the USA and one other country, with guidance/input from 12 onion growers/stakeholders serving on the project Stakeholder Advisory Panel. The proposal was funded at $4.0 million with matching funding of $4.2 million. The 4-year project started in October 2019.

Publications

  • Type: Journal Articles Status: Published Year Published: 2019 Citation: Knerr, A.J., Wheeler, D., Schlatter, D., Sharma-Poudyal, D., du Toit, L.J., and Paulitz, T.C. 2019. Arbuscular mycorrhizal fungal communities in organic and conventional onion crops in the Columbia Basin of the Pacific Northwest USA. Phytobiomes 2:194-207.
  • Type: Journal Articles Status: Published Year Published: 2019 Citation: du Toit, L.J., Derie, M.L., Holmes, B.J., Miller, C.E., Brouwer, L.R., Waters, T.D., and Darner, J. 2019. Effects of the arbuscular mycorrhizal fungi inoculant Mykos Gold Granular on pink root and yield in commercial onion bulb crops near Irrigon, OR, 2017. Plant Disease Management Reports 13:V008.
  • Type: Journal Articles Status: Published Year Published: 2019 Citation: du Toit, L.J., Derie, M.L., Holmes, B.J., Morgan, P., Brouwer, L.R., and Waters, T.D. 2019. The influence of soil phosphorus levels on onion root colonization by mycorrhizal fungi from commercial inoculants, 2017. Plant Disease Management Reports 13:V009.
  • Type: Journal Articles Status: Published Year Published: 2019 Citation: du Toit, L.J., Derie, M.L., Holmes, B.J., Henrichs, B.A., Winkler, L.R., Waters, T.D., and Darner, J. 2018. The effects of arbuscular mycorrhizal fungal inoculants on pink root and yield in an onion crop near Paterson, WA, 2016. Plant Disease Management Reports 12:V102.
  • Type: Other Status: Published Year Published: 2019 Citation: du Toit, L., and Yorgey, G. 2018. Onion stunting after cereal cover crops. Page 6. Timing of glyphosate applications to wheat cover crops to reduce onion stunting caused by Rhizoctonia solani. Page 7. Efficacy of fungicide applications to manage onion stunting caused by Rhizoctonia spp. Pages 7-8. In: Strip-tillage for onions and sweet corn, Lorin Grigg. Farmer to Farmer Case Study Series on Increasing Resilience among Farmers in the Pacific Northwest. Washington State University Extension PNW702.
  • Type: Other Status: Published Year Published: 2019 Citation: Winkler, L., du Toit, L., and Waters, T. 2019. Mycorrhizal inoculants: Yea or nay? The effects of mycorrhizal inoculants on onion crops in the Columbia Basin. Onion World Feb. 2019:10-14. https://issuu.com/columbiamediagroup/docs/feb_2019_onion_world_web?e=34405975/67413329
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: du Toit, L.J., Waters, T.W., Derie, M.L., and Brouwer, L. 2019. Can onion growers benefit from mycorrhizal inoculants? 2019 combined meeting of the National Onion Association, National Allium Research Conference, and International Allium Research Symposium, 24-27 Jul. 2019, Madison, WI. (Abstract)
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Ilyas, U., Raizada, M., du Toit, L.J., and McDonald, M.R. 2019. Mycorrhizal fungi in the roots of onion and carrot in relation to mycorrhizal fungal inoculant and soil phosphorus. Plant Canada 2019, 7-10 Jul. 2019, University of Guelph, Ontario, Canada. Abstract 192. (Abstract)
  • Type: Websites Status: Published Year Published: 2019 Citation: Pacific Northwest Vegetable Extension Group (PNW VEG) website (http://mtvernon.wsu.edu/path_team/vegpath_team.htm), a tri-state Extension team with resources on diverse vegetables grown in the PNW USA. Sections on onions include the Photo Gallery (http://mtvernon.wsu.edu/path_team/onion.htm) and IPM Resources (http://mtvernon.wsu.edu/path_team/ipmResources.htm#onion).
  • Type: Other Status: Published Year Published: 2019 Citation: du Toit, L.J., Waters, T.W., and Pappu, H.R. 2019. 2018 Annual report for Washington State participants in the W-3008 onion multistate project. Sep. 2019. 5 pp.
  • Type: Websites Status: Published Year Published: 2019 Citation: WSU Onion Alerts (https://mailchi.mp/wsu/wsu-onion-alert-aug-14-1303793?e=72ba613792): Time-sensitive topics covered in seven articles between May 30 and August 21 of 2019 included downy mildew, fungicides, thrips, nematodes, iris yellow spot, irrigation, and powdery mildew.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2019 Citation: du Toit, L.J. 2019. Specialty vegetable seed production. Invited presentation, Western Region IR-4 SLR/CLC Meeting, 9-10 April 2019, Mount Vernon, WA. (25 people)
  • Type: Conference Papers and Presentations Status: Other Year Published: 2019 Citation: du Toit, L.J. 2019. Regionally appropriate fungicide programs. Invited presentation, Wilbur Ellis Grower Meeting, 21 Feb. 2019, La Conner, WA. (50 people)
  • Type: Conference Papers and Presentations Status: Other Year Published: 2019 Citation: du Toit, L.J. 2019. Onion disease management. Invited presentation and discussion with AgriNorthwest growers, 7 Feb. 2019, Pasco, WA. (50 people)
  • Type: Conference Papers and Presentations Status: Other Year Published: 2019 Citation: du Toit, L.J. 2019. Late-season disease management in onion production. Invited presentation at Clearwater Supply Winter Growers Meeting, 6 Feb. 2019, Ontario, OR. (75 people)
  • Type: Conference Papers and Presentations Status: Other Year Published: 2019 Citation: du Toit, L.J. 2019. Regionally appropriate fungicide programs. Invited presentation, Columbia Basin Crop Consultants Association Short Course, 4-5 Feb. 2019, Moses Lake, WA. (150 people)
  • Type: Conference Papers and Presentations Status: Other Year Published: 2019 Citation: du Toit, L.J. 2019. Management of Rhizoctonia in onion seedbeds and direct-drilled crops, and postharvest management of black mold in onion crops. Invited presentation, KORKOM onion growers, 23 Jan. 2019, Ceres, South Africa. (15 people)
  • Type: Conference Papers and Presentations Status: Other Year Published: 2019 Citation: du Toit, L.J. 2019. Appropriate use of fungicides. Invited presentation, Columbia Basin Vegetable Seed Association Annual Meeting, 15 Feb. 2019, Moses Lake, WA. (75 people)
  • Type: Conference Papers and Presentations Status: Other Year Published: 2019 Citation: du Toit, L.J. 2019. Appropriate use of fungicides. Invited presentation, Annual Basin Producers 2019 Pesticide Recertification Day, 14 Feb. 2019, Moses Lake, WA. (275 people)
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: du Toit, L.J. 2018. Management of Fusarium basal rot of onion. Invited presentation, Onion Session of the Pacific Northwest Vegetable Association Annual Convention & Trade Show, 14-15 Nov. 2018, Kennewick, WA. https://pnva.org/2018-pnva-conference-presentations/ (200 people)
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: du Toit, L.J. Regionally appropriate fungicide programs for common onion pathogens in the Columbia Basin. Invited presentation, Onion Session of the Pacific Northwest Vegetable Association Annual Convention & Trade Show, 14-15 Nov. 2018, Kennewick, WA. https://pnva.org/2018-pnva-conference-presentations/ (200 people)
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Waters, T. D., (2018). Thrips Management in Dry Bulb Onions. SW Ag Summit, Yuma, AZ. (100 people).
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Ingham, R., and Waters, T.D. 2018. Nematode management in onions. Pacific Northwest Vegetable Association Annu. Conv. & Trade Show, Kennewick, WA. (200 people).
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Waters, T.D. 2018. Thrips control in dry bulb onions. Pacific Northwest Insect Management Conference, Portland, OR. (60 people).
  • Type: Conference Papers and Presentations Status: Other Year Published: 2019 Citation: Waters, T.D. 2018. Insect control in potato and onion. Corteva Regional Customer Meeting, Las Vegas, NV. (60 people).
  • Type: Conference Papers and Presentations Status: Other Year Published: 2019 Citation: Waters, T. D. 2018. Thrips and seedcorn maggot control in onions. 2018 Walla Walla Onion Growers Meeting organized by CHS Primeland. Walla Walla, WA. (20 people).
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Waters, T. D. 2018. Potato and onion insect IPM update. AgriNorthwest Agronomy Meeting. Kennewick WA. (50 people).
  • Type: Conference Papers and Presentations Status: Other Year Published: 2019 Citation: du Toit, L.J. Soilborne disease management in carrot, onion, brassica, and beetroot production in sandy soils of the Sandveld region of South Africa. Invited discussion/workshop with agronomists and production managers for Laastedrif Farm, 23 Jan. 2019, Ceres, South Africa.
  • Type: Other Status: Other Year Published: 2019 Citation: Washington State University Onion Field Day, 29 August 2019, L&L Ag Production, Connell, WA. 125 expected attendees - Growers crop consultants, and allied industry members plus researchers and extension personnel.


Progress 11/08/17 to 09/30/18

Outputs
Target Audience:Onion and onion seed growers, onion seed industry personnel, extension personnel, researchers, consultants, graduate and undergraduate students, postdoctorates, and technical staff. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Attendance at professional meetings for presenting results, networking with specialists on specific crops/diseases, and providing graduate students and technical staff with professional development opportunities, including presenting their research and learning extension/communication skills at field days, grower meetings, and professional conferences. In 2018, the W-3008 onion multi-state team received the USDA CSREES Excellence in Multistate Research Award for the Western Region for the previous iteration of this team, the W-2008. Trained one PhD student in biological and molecular aspects of IYSV. The student graduated in fall 2018. How have the results been disseminated to communities of interest?See the list of service and event noted in 'Other Products' above. Numerous presentations, workshops, field days, seminars, W-3008 annual meeting, etc. throughout the year in grower/stakeholder meetings, scientific meetings, etc. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Obj. 1) Evaluate onion germplasm for resistance to pathogens and insects: We continued our efforts to improve the transmission efficiency of IYSV to onion with a goal to increase the efficiency of screening of onion germplasm for virus resistance under controlled conditions. We successfully reproduced disease symptoms by mechanical inoculation. Obj. 2) Investigate the biology, ecology and management of onion thrips and other pests: We evaluated several conventional and organic pesticides for their ability to control onion thrips populations. We found the organic product Entrust to be the most efficacious of the organic materials tested. For the conventional products, Radiant, Agrimek, Exirel, Minecto Pro, and Lannate were the most efficacious products. Movento and Torac provided a moderate level of control. Thrips from commercial onion fields were evaluated for their level of resistance to the commonly used insecticide Lannate (methomyl). Varying levels of resistance were detected, presumably based on the frequency of use of the product. The organic field, that has not had the product applied contained thrips that were completely susceptible to the field dose of the product. The four conventional fields that were evaluated ranged from 58 to 80% mortality at the field dose. These levels of control at the field dose suggest the onset of field resistance to Lannate. This information will be used to help producers modify their insect management strategies to mitigate further resistance development and achieve adequate control of onion thrips. Obj. 3) Investigate the biology, epidemiology and management of onion plant pathogens: Finished a 3-year WSDA SCBG project on evaluating arbuscular mycorrhizal fungi (AMF) inoculants for enhancing onion production and managing soilborne pathogens in the Columbia Basin. Published results showing that that moderate to high soil P levels typically used by onion growers in this region significantly reduce root colonization by AMF, negating the benefits of AMF inoculants in onion crops. Set up a field trial in Pasco, WA to evaluate products for control of downy mildew in onion bulb production. Generated infected plants using inoculum obtained off an infected, overwintered onion seed crop. Warm, dry conditions in the Columbia Basin in 2018 limited development of downy mildew to the point there was inadequate disease to differentiate efficacy of the products. Provided diagnosis and associated management recommendations for 25 onion samples from growers in the Pacific Northwest and western USA. Obj. 4) Facilitate discussions between W3008 participants and onion industry stakeholders that will advance onion pest and disease management: W-3008 annual meeting was held in Kennewick, WA on 13 Nov. 2018 with ~60 participants from across the USA. Attendees shared updates on onion production in various states, and progress reports on onion research and extension projects. The meeting was followed by a field tour and packing facility/storage facility tour outside Pasco. Tim Waters and Lindsey du Toit were the local arrangements committee. Lindsey du Toit served as past chair of the W-3008 multi-state project in 2018. du Toit prepared a summary of the W-3008 annual meeting for publication in the January or February 2019 issue of Onion World.

Publications

  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Knerr, A.J., Wheeler, D., Schlatter, D., Sharma-Poudyal, D., du Toit, L.J., and Paulitz, T.C. 2018. Arbuscular mycorrhizal fungal communities in organic and conventional onion crops in the Columbia Basin of the Pacific Northwest USA. Phytobiomes 2: in press. http://dx.doi.org/10/.1094/PBIOMES-05-18-0022-R
  • Type: Journal Articles Status: Published Year Published: 2018 Citation: du Toit, L.J., Derie, M.L., Holmes, B.J., Henrichs, B.A., Winkler, L.R., Waters, T.D., and Darner, J. 2018. The effects of arbuscular mycorrhizal fungal inoculants on pink root and yield in an onion crop near Paterson, WA, 2016. Plant Disease Management Reports 12:V102.
  • Type: Other Status: Published Year Published: 2018 Citation: du Toit, L., and Yorgey, G. 2018. Onion stunting after cereal cover crops. Page 6. Timing of glyphosate applications to wheat cover crops to reduce onion stunting caused by Rhizoctonia solani. Page 7. Efficacy of fungicide applications to manage onion stunting caused by Rhizoctonia spp. Pages 7-8. In: Strip-tillage for onions and sweet corn, Lorin Grigg. Farmer to Farmer Case Study Series on Increasing Resilience among Farmers in the Pacific Northwest. Washington State University Extension PNW702.
  • Type: Other Status: Published Year Published: 2018 Citation: Winkler, L., du Toit, L., and Waters, T. 2018. Do onion growers benefit from mycorrhizal inoculants ? The effects of mycorrhizal inoculants on onion crops in the Columbia Basin. Onion World Nov. 2018: in press.
  • Type: Websites Status: Published Year Published: 2018 Citation: Wohleb, C.H., Waters, T.W., and du Toit, L.J. 2018. Washington State University Extension Onion Alerts. Contributed disease information and photos for WSU Onion Alerts released online on 24 Apr., 23 May, 31 May, 3 Jul., 16 Aug., 27 Aug., 1 Oct., and 31 Oct. 2018. https://us13.campaign-archive.com/?u=2eff8714011ff4bfba18a0704&id=d75dc96e7f
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: du Toit, L.J. Management of Fusarium basal rot of onion. Invited presentation, Onion Session of the Pacific Northwest Vegetable Association Annual Convention & Trade Show, 14-15 Nov. 2018, Kennewick, WA. (200 people)
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: du Toit, L.J. Regionally appropriate fungicide programs for common onion pathogens in the Columbia Basin. Invited presentation, Onion Session of the Pacific Northwest Vegetable Association Annual Convention & Trade Show, 14-15 Nov. 2018, Kennewick, WA. (200 people)
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: du Toit, L.J. Impact of fungicides on plant health. Invited presentation, Pest Management Session of the Pacific Northwest Vegetable Association Annual Convention & Trade Show, 14-15 Nov. 2018, Kennewick, WA. (175 people)
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: du Toit, L.J. Complexities and synergies in large-scale conventional and organic agriculture in Washington. Invited presentation, Organic Session of the Pacific Northwest Vegetable Association Annual Convention & Trade Show, 14-15 Nov. 2018, Kennewick, WA. (150 people)
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: du Toit, L.J. Case studies of the complexity of seedborne and seed transmitted fungi affecting regional and global seed trade. Guest speaker at the joint symposium of the American Phytopathological Society (APS) and the Società Italiana di Patologia Vegetale (SIPaV), 24th National Congress of SIPaV, 5-7 Sep. 2018, Ancona, Italy. (see Abstracts above) (~250 people)
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: du Toit, L.J. Conventional and organic disease control strategies for specialty crops. Invited presentation at 2018 Colorado Fruit & Vegetable Growers⿿ Association Annual Meeting, 19-20 Feb. 2018, Denver, CO (50 people)
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: du Toit, L.J. Allium, bean, and crucifer seed quarantines in Washington: Current status and future needs. Annual Basin Producers⿿ 2018 Pesticide Recertification Day, 19 Jan. 2018, Moses Lake, WA (175 people)
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: du Toit, L.J. A review of onion diseases ⿿ identification and management. 4-hour invited presentation at the 2018 Walla Walla Onion Growers⿿ Meeting organized by CHS Primeland, 18 Jan. 2018, Walla Walla, WA (12 people)
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: du Toit, L.J. Allium, bean, and crucifer seed quarantines in Washington: Current status and future needs. Columbia Basin Crop Consultants⿿ Assoc. Short Course, 17 Jan. 2018, Moses Lake, WA (150 people)
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: du Toit, L.J. Seedborne and seed transmitted plant pathogens. Columbia Basin Crop Consultants⿿ Assoc. Short Course, 17 Jan. 2018, Moses Lake, WA (100 people)
  • Type: Other Status: Published Year Published: 2018 Citation: du Toit, L.J., Waters, T., Derie, M., Holmes, B., Darner, J., Henrichs, B., Knerr, J., Miller, C.E., Morgan, P., and Brouwer, L. 2018. Do AMF inoculants help onion crops? Pp. 11-12 in: 2018 Washington State University Onion Field Day Handouts. 13 pp.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Tabassum, A., S.V. Ramesh, Y. Zhai, and H.R. Pappu. 2018. Molecular evolutionary genomics and population structure of Iris yellow spot virus (Family: Tospoviridae; Genus: Orthotospovirus). 11th International Congress of Plant Pathology, Boston, MA. July 29-August 3, 2018.
  • Type: Other Status: Published Year Published: 2018 Citation: Waters, T.D., Darner, J., Adesanya, A., Walsh, D. and Kinion, D. Entomology Research Report for Onions. In: 2018 Washington State University Onion Field Day Handouts. 13 pp.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Waters, T.D. Thrips Control in Dry Bulb Onions. Pacific Northwest Insect Management Conference, January 8, 2018 Portland, OR. (45 people)
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Waters, T. D. Insect IPM Update. Simplot Grower Solutions Meeting, February 6, 2018. Pasco, WA. (65 people)
  • Type: Other Status: Published Year Published: 2018 Citation: Waters, T.D. Insect Control in Potato and Onion. Corteva Regional Customer Meeting, February 15, 2018. Las Vegas, NV. (125 people).
  • Type: Other Status: Published Year Published: 2018 Citation: Waters, T. D. Thrips and Seedcorn Maggot Control in Onions. 2018 Walla Walla Onion Growers⿿ Meeting organized by CHS Primeland, 18 Jan. 2018, Walla Walla, WA (12 people)
  • Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Waters, T. D. Potato and Onion Insect IPM Update. Agrinorthwest Agronomy Meeting. February 6, 2018. Kennewick WA. (45 people).