July 2002 NewsletterLindsey du Toit and Debra Inglis, editors
WSU Mount Vernon NWREC
16650 State Rte 536, Mount Vernon, WA 98273-4768
360-848-6140 (tel), 360-848-6159 (fax)
WSU Vegetable Pathology Team Newsletter
Welcome to the July 2002 edition of Washington State University's Vegetable Pathology Extension Team newsletter, the third edition of the 2002 growing season. This newsletter follows the team's July conference call when team members discussed current vegetable diseases occurring in the state, their diagnoses and control. We thought it would be fun to focus the July issue on ONIONS! Did you know that onions are Washington's third-highest value vegetable crop? Approximately 18,000 acres of storage onions and approximately 800 acres of non-storage onions were harvested in Washington in 1999. For more onion statistics, visit the WSU Vegetable Pathology Team's website at: https://mtvernon.wsu.edu/path_team/onion.htm and https://mtvernon.wsu.edu/path_team/Overview.htm. If you have questions or comments regarding vegetable diseases or WSU's Vegetable Pathology Team, contact Debbie Inglis (firstname.lastname@example.org) or Lindsey du Toit (email@example.com).
Onion Smut Detected
Onion smut has been detectedthis year in the south Columbia Basin (Franklin County). Although this disease is not new to the state, previous reports have been limited to western WA and the following counties in eastern WA: Walla Walla, Yakima, Spokane, and Kittitas. The large acreage planted to onion in Washington justifies grower awareness of the disease and appropriate measures to minimize spread of the pathogen.
The fungus responsible for smut on onions (Urocystis colchici) can survive many years as a saprophyte in infested soil. Symptoms of smut appear in the seedling stem as it emerges, and blisters of black powdery spores result. Seedlings either die at emergence or produce distorted bulbs with smutty lesions. Seed treatment for next year's crop is highly advisable. Consult PICOL for products registered for use in WA at: https://picol.cahe.wsu.edu/labels/Labels.php
Smut on onions (photos courtesy of L. du Toit)
PLACES TO FIND INFORMATION ABOUT ONIONS
Onion Field Day Scheduled
The WSU Onion Field day is scheduled for Aug. 30 at 9 am near Quincy. For information and directions, contact Gary Pelter at firstname.lastname@example.org
Need More Information About Growing Onions?
Information about growing onions in the PNW can be found in the Commercial Vegetable Production Guides from Oregon State University on the web at: https://www.orst.edu/Dept/NWREC/allium.html
WSU publications on onions can be found at:
Onion Cultivar Demonstration and Storage Trial Results Available
Since 1984, Gary Pelter, WSU Extension Agent, has carried out annual demonstration trials and storage trials of onion cultivars in the Columbia Basin. Results of the demonstration trials include information on maturity, yield, and bulb size (# of bulbs >4", 3–4", 2.25–3", <2.25", and # of defects). Results of the onion storage trials include information on incidence of neck rot and other storage rots, # of sprouted bulbs, # of bulbs with single centers, bulb firmness, scale quality, and uniformity of bulb shape. For copies of the results from 1984 to 2000, contact Gary Pelter at (509) 754-2011 ext. 413 or email@example.com. Results of the 2001 trials can be accessed at the Grant-Adams area website:
2001 Onion Storage Demonstration Results – https://grant-adams.wsu.edu/
2001 Onion Varietal Demonstration Results – https://grant-adams.wsu.edu/agriculture/index.htm
Onion World: Voice of
the Onion Industry
For information on the latest issues affecting the onion industry, subscribe to Onion World: Voice of the Onion Industry by contacting the Executive Office of Columbia Publishing, 417 North 20th Avenue, Yakima, WA 98902; tel. (509) 248-2452 or fax (509) 248-4056. Onion World is published eight times a year, and the annual subscription fee is $15.
An estimated $50 million crop loss affecting about 60% of Georgia's sweet onion crop this year was probably caused by a combination of warm fall temperatures that promoted bolting, heavy spring frosts that allowed Stemphylium leaf blight to develop followed by an outbreak of sour skin (Pseudomonas=Burkholderia cepacia), and unusually hot/humid weather in April. Growers harvested only 2 million bushels of what should have been a 5 million bushel crop.
Onion Crop Profile Under
A Crop Profile for onion in Washington is being developed by Gary Pelter and Erik Sorensen, WSU Extension Agents and members of the WSU Vegetable Pathology Team. The Onion Crop Profile will be available in August or September. A Crop Profile is a condensed production story of an individual agricultural commodity. It includes information on production; cultural practices; pest, disease, and weed problems and management practices; and, IPM or alternative strategies for managing pests, diseases, and weeds. The purpose of a Crop Profile is to provide an overview of the importance of that commodity, identify production/crop protection concerns, and suggest alternative management opportunities. For further information on Crop Profiles, access the following website: https://www.tricity.wsu.edu/~cdaniels/CropProfiles.pdf. For questions on Crop Profiles completed for Washington State, contact Catherine Daniels, WSU Pesticide Information Coordinator, at firstname.lastname@example.org or (509) 372-7495.
2002 National Allium
Research Conference To Be Held in Pasco
The 2002 National Allium Research Conference will take place December 12-14 in Pasco, WA at the DoubleTree Hotel. The conference includes two days of oral and poster presentations, followed by a tour of the onion industry in the Pacific Northwest (production, storage, and processing facilities). The deadline for submitting papers/posters has been extended to September 1, 2002. For information contact Wendy Peay at (509) 547-0701, email@example.com or visit the conference website at https://narc2002.wsu.edu.
White Rot Conference Recently Held
The 7th International Allium White Rot Conference was held at Harris Ranch, CA on June 4-8, 2002. The meeting included sessions (oral presentations and interactive discussions) on the history, geographic distribution, and importance of white rot caused by Sclerotium cepivorum; the biology and epidemiology of this fungal pathogen; and, management practices for white rot, including fungicides, sclerotium germination stimulants, biological control, and host resistance. The meeting was attended by delegates from Canada, Mexico, the Netherlands, New Zealand, and the US. Proceedings from this conference will be posted later this year on the website of the Canadian Phytopathological Society (https://www.cps-scp.ca/conference.html)
Note: A white rot quarantine is enforced by the WSDA for Grant, Adams, and Franklin Counties.
INFORMATION ABOUT ONION DISEASES & PESTS
Onion Disease Compendium
APS Press offers the "Compendium of Onion and Garlic Diseases" edited by Howard F. Schwartz and S. Krishna Mohan. The book includes an introduction to the genus Allium; extensive information about infectious biotic diseases and noninfectious abiotic conditions of onion and garlic, including diagnosis, epidemiology, and disease management; and, 100 color images of biotic and abiotic problems on onion and garlic to assist with diagnoses. The cost of the compendium is $49.00. To order call 1-800-328-7560 (ISBN 0-89054-170-1) or view: https://store.yahoo.com/shopapspress/41701.html
Some Additional References on Diseases of Allium Crops
- Onion Diseases: A Practical Guide for Seedsmen, Growers, and Agricultural Advisors. B.K. Gabor, Editor. For copies of this handy reference, contact your local Seminis dealer. This book includes brief descriptions of the major biotic and abiotic diseases of onions, with excellent color photos accompanying each description.
- Diseases and Pests of Vegetable Crops in Canada. 1994. R.J. Howard, J.A. Garland, and W.L. Seaman, Editors. The Canadian Phytopathological Society and the Entomological Society of Canada, Ottawa, Ontario, Canada. For copies contact the ESC at (613) 725-2619 or by fax at (613) 725-9349. This extensive reference covers diseases and insect pests of a wide range of vegetable crops, including diseases of greenhouse vegetables, with color photos of the pests and diseases.
- Onions 1993. D.A. Bender. Chapter 12, In: Nutrient Deficiencies & Toxicities in Crop Plants. W.F. Bennett, Editor. The American Phytopathological Society Press, St. Paul, MN. To order a copy of this book, visit the APS Press website at: https://www.shopapspress.org/41515.html or call 1-800-328-7560 (ISBN 0-89054-151-5).
Photos of Onion Diseases
WSU's Vegetable Pathology Team maintains a vegetable disease photo gallery which includes photos of diseases on onion and garlic. Visit the site at: https://mtvernon.wsu.edu/path_team/diseasegallery.htm#onion
- Doug Walsh, WSU Entomologist, is investigating control of thrips (western flower thrips and onion thrips) in onion and onion seed crops in the Columbia Basin.
- Lindsey du Toit, WSU Vegetable Seed Pathologist, has projects on Botrytis neck rot/scape blight of onion/onion seed crops: a) a survey of seed crops to determine the Botrytis species prevalent in this semi-arid region and the level of infection on the harvested seed; b) the importance of seedborne Botrytis spp. of onion as measured by the rate of seed-to-seedling transmission; c) a fungicide efficacy trial for onion seed crops; d) survival of Botrytis allii in culled onions.
- Gary Pelter, WSU Extension Agent, has an onion demonstration trial as well as weed control trials for onion seed crops located in the northern Columbia Basin.
For further information on any of these projects, contact the individual researchers: Doug Walsh at (509) 786-2226 or firstname.lastname@example.org, Lindsey du Toit at (360) 848-6140 or email@example.com, and Gary Pelter at (509) 754-2011 ext. 413 or firstname.lastname@example.org.
2001 Field Research
Reports on Onion Diseases
The 2002 volume of Fungicide and Nematicide Tests (results of 2001 published in 2002) include two reports of field research done on onions: 1) Mohan, S.K. and Bijman, V. P. Evaluation of fungicide sprays for control of downy mildew in onion, Cayon County, Idaho, 2001, Report No. 57:V052; and, 2) Langston, Jr., D. B. Evaluation of spray programs for control of foliar pathogens (Botrytis & Alternaria), 2001, Georgia, U.S., Report No. 57:V051. For access, review https://www.apsnet.org/online/FNtests/vol57/top.htm
Important Diseases on Onion in Washington and Their Management
|Basal rot||Fusarium oxysporum
f. sp. cepae
plants: onion, other cultivated Allium spp.
|Black mold||Aspergillus niger||
plants: onion, fruits, other vegetables
|Botrytis leaf blight||Botrytis squamosa||
plant: Allium spp. (garlic highly resistant, chive immune)
|Bacterial soft rot||Erwinia Carotovora
plants: most Allium spp., other vegetables (carrot, celery,
|Slippery skin||Burkholderia gladioli pv. alliicola||
|Yeast soft rot||Kluyveromyces marxianus var. marxianus||
|Downy mildew||Peronospora destructor||
plants: wild and cultivated Allium spp.
|Iris yellow spot||IYSV||
plants: onion, garlic, leek, iris, lisianthus; IYSV has NOT been
found in Washington, but has been reported in eastern Oregon, Idaho and
|Neck/bulb rot||Botrytis allii||
plants: onion, shallot, leek, garlic, chives
|Stubby root nematodes||Paratrichodorus minor||
plants: wide host range
|Pink root||Phoma terrestris||
|Purple blotch||Alternaria porri||
plants: onion, garlic, leek, probably other Allium spp.
= P. porri
plants: Allium spp. (differentially infected)
|White rot||Sclerotium cepivorum||
plants: onion, garlic
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