Pacific Northwest Vegetable Extension Group

of Washington State University, Oregon State University, and University of Idaho

Newsletter Archives

June 2005 Newsletter

Lindsey 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 June 2005 newsletter of the WSU Vegetable Pathology Team! We hope you are having a productive season. We start this vegetable season feeling the loss of the tremendous expertise and skills of several extension educators who were members of the Team until they each retired in the past year: Dyvon Havens from Skagit Co., Gary Pelter from Grant and Adams Counties, and Erik Sorensen from Franklin Co. However, we are very pleased to introduce 5 new Team members who bring valuable expertise to our program:

  • Dr. Richard Larson: Rich is a USDA virologist located at WSU Prosser IAREC. Rich’s program is focused on viruses of legume crops using both applied and molecular technology, and virus resistance in common bean. Rich also conducts research on soilborne diseasesof forage crops, including identification of resistance sources using real-time PCR. More information on this program can be found at, and Rich can be contacted at or (509) 786-9259
  • Dr. Mark Pavek: Mark was hired by WSU in 2004 as an extension/research horticulturalist located at WSU Pullman, and has responsibilities for potatoes and vegetable crops. Mark completed his BS degrees in plant science and ag. economics & agribusiness at the University of Idaho, followed by an MS degree in plant science at the same institute. Mark completed his PhD degree in horticulture at WSU with his dissertation on potato agronomy. Mark has worked as Assistant Farm Manager for SSI Land & Cattle in Idaho, Product Development Assistant for Syngenta/Zeneca in Idaho, and PNW Field Research Manager for NatureMark Potatoes, a division of Monsanto. Mark brings experience in 11 years of commercial farming, 18 years of applied ag-research, and 7 years extension. Mark currently serves as chair of the Western Regional Potato Variety Development Team (WERA-27), University Advisor Board Member for the Pacific Northwest Vegetable Assoc., and is involved with the Potato Association of America. Mark can be contacted at or (509) 335-6861. See the WSU potato website at
  • Dr. Lyndon Porter: Lyndon was hired as the USDA legume pathologist located at WSU Prosser IAREC in 2004, having completed his PhD in plant pathology at WSU. Lyndon’s program conducts basic and applied research on the nature, cause, and control of soilborne diseases of edible legumes. The program investigates host-pathogen relations and disease interactions of significance in edible legumes, provides research on pea diseases in the Pacific Northwest and expertise on soil fungal interactions with other disease and non-disease organisms, and develops new methods and techniques to study resistance to soilborne diseases, pathogen variability, germplasm development and improvement, pest management practices, and the use of beneficial organisms to improve edible legume yield and quality. Lyndon can be contacted at or (509) 786-9237.
  • Photo of Dr. Naidu RayapatiDr. Naidu Rayapati: Naidu serves as one of the virologists at WSU Prosser IAREC (since 2004), with a focus on grape virology, plant virology, biological and molecular aspects of viruses; virus-vector interactions; virus diagnostics; conventional and biotechnological approaches for virus and vector resistance; and international agriculture. Naidu can be contacted at or (509) 786-9215.
  • Photo of Katerina RigaDr. Ekaterini Riga: Katerina is the only nematologist in WA, with a combination of research, teaching, and extension responsibilities. Katerina’s program is based out of WSU Prosser IAREC, and focuses on the biology, ecology, host-parasite relationships, and management of plant-parasitic nematodes on crops in WA. We appreciate having a nematologist contribute to the Team’s expertise, as we have seen significant nematode problems on vegetable crops in WA. Contact Katerina at or (509) 786-9256.
  • Photo of Mark TrentMark Trent: As of June 2005, Mark is extension educator for Grant & Adams Counties in the Columbia Basin. Mark spent the previous 2 years at the University of Arkansas, running the soybean cultivar trial with Dr. Rick Cartwright. Mark completed his MS degree in plant pathology at Oklahoma State University, investigating white rust of spinach for his MS thesis. During this time, Mark also worked as a field research technician. Mark raised peanuts and cattle in Oklahoma prior to starting his graduate program. Mark’s responsibilities as Extension Educator cover horticultural crops, including potatoes, vegetables, and vegetable seed crops. Mark can be contacted at or (509) 754-2011 ext. 413.


Extension publications

Drought Advisory: Vegetable Crops, WSU Extension publication EM4830E, might be valuable to growers in 2005 given the drought advisory conditions this season. The bulletin can be downloaded at:, or ordered from WSU Bulletins, PO Box 645912, Pullman, WA 99164-5912.

Potato Leaf Roll, WSU Extension publication EB1994E, prepared in 2005 by Dennis Johnson, plant pathologist at WSU Pullman, can be downloaded at:, or ordered from WSU Bulletins, PO Box 645912, Pullman, WA 99164-5912.

Field days

WSU Vegetable Seed Field Day will be held at the WSU-NWREC in Mount Vernon on Thursday, 16th June from 3 – 6 pm. Weed control, disease management, and entomology field trials will be demonstrated. The WSDA has approved 3 pesticide license recertification credits for the field day. For more information contact Lindsey du Toit ( or 360-848-6140) or Tim Miller (

WSU Othello Potato Field Day will be on 24th June 2005 from 8:30 am – 1:00 pm at the WSU Othello REU. In addition, potato seed lot readings will take place on 7th June and 21st June at WSU Othello REU. For more information contact Mark Pavek at or (509) 335-686.

The Icebox Watermelon Field Day will take place on 24th August 2005 from 2 – 4 pm at the WSU Vancouver REU. For more information contact Carol Miles at or (360) 576-6030 ext. 20.

The WSU Onion Cultivar Field Day will take place on 26th August 2005 from 9 am – noon at L&L Farms near Connell, WA. Replicated plots of 49 cultivars will be on display, with research updates on neck rot and iris yellow spot virus. A BBQ will follow, at the Scooteney Reservoir Recreational Area. For more information contact Lindsey du Toit at or (360) 848-6140, or Mark Trent at or (509) 754-2011 ext. 413.


Nematology Short Course on 7th July 2005 from 9:30 am – noon at the WSU Prosser IAREC. Guest speaker: Dr. Roy Neilson, Nematologist, Scottish Crop Research Institute, Invergowrie, Dundee, Scotland. The topics of the workshop are: 1) "Nematodes, here, there and everywhere" with emphasis on general biology of free living nematodes. 2) "Virus-vector nematodes" with emphasis on P. allius, P. teres and P. minor. The workshop is open to everyone. Location: Main Conference Room, WSU-Prosser IAREC, 24106 N. Bunn Rd., Prosser, WA. For more information contact Katerina Riga at or (509) 786-9256.


31st International Carrot Conference at the Sandman Hotel Montreal in Longueuil, Quebec, Canada on 11-14 September 2005. Visit the conference website at

Pacific Northwest Vegetable Association Annual Convention & Trade Show at the Red Lion Hotel in Pasco, WA on 17–18 November 2004. Visit the PNVA website at

31st Annual Washington Tilth Producers’ Convention on 11–13 November 2005 at the Wenatchee Convention Center in Wenatchee, WA. There will be a pre-conference symposium titled ‘Alternative Energy on the Farm’ on Friday 11th November from 10 am – 5 pm, with keynote speaker Fred Provenza from Utah State University. View the Tilth website at or call Nancy Allen at (206) 442-7620.

Annual meeting of the Western WA Horticulture Association, Puget Sound Seed Growers’ Association, and the Northwest Bulb Growers’ Association at the Marriott Hotel in SeaTac, WA on 4–5 January 2006. Visit the WWHA website at:

The Organic Seed Conference in Troutdale, OR on 10–12 January 2006. For more information contact the Organic Seed Alliance at or P.O. Box 772, Port Townsend, WA 98368 or (360) 385-7192.

Digital photography resources

For helpful hints on digital photography, including taking microscopic images, take a look at the following websites:

  1. UK Plant Pathology webpage ‘Digital Imaging and Microscope Information’:
  2. Richard Drees' webpage ‘Digital Imaging for Microscopy’:

2006 Vegetable Conferences

Conferences text


In April 2005, the CA Fresh Carrot Advisory Board (CFCAB) released a letter to some Pacific Northwest seed companies expressing concern over a new virus disease of carrots, Carrot virus Y (CarVY), which has been detected in Australia since 1997. CarVY has not been found in the US, but the CFCAB stated their concern about the possibility of the virus being introduced into the US, after preliminary research in Australia suggested the possibility the virus might be transmitted from carrot seed at a very low rate. The CFCAB proposed that carrot seed produced in Australia not be accepted into the US unless the seed has been certified to be “free of CarVY” and the seed lot indexed for the disease. However, Roger Jones, virologist in Western Australia, recently stated in an email correspondence to Lindsey du Toit that “exhaustive tests involving grow out of many thousands of seedlings from plants infected with the virus and testing the seedlings by ELISA failed to confirm that seed transmission occurs”.

The following is a brief summary of information on CarVY published in Farmnote No. 29/2003 by the Department of Agriculture, Government of Western Australia (the farmnote, including photos of infected plants, can be viewed at: Distribution: All carrot producing regions of Australia

Symptoms: Leaf symptoms include a chlorotic mottle, marginal necrosis, increased subdivision of leaflets (feathery appearance to the foliage), and stunting. Root symptoms range from mild (when infection occurs later in the season) to severe (when infection occurs on seedlings up to 6 weeks after germination), and include shortened, stubby, knobby roots that are unmarketable. Mild symptoms may include thinner carrots that are only slightly distorted. The virus has been dubbed ‘Michelin virus’ because severely infected roots resemble the Michelin man.

Aphid transmission: CarVY is transmitted non-persistently by aphids, i.e., aphids acquire the virus rapidly when feeding on infected plants, and lose the virus rapidly from their mouthparts after feeding on healthy or non-host plants. Roger Jones and his team in Western Australia have conducted greenhouse tests on the relative ability of different aphid species to transmit the virus. The following colonizing aphid species transmitted the virus, in order of decreasing effectiveness: Myzus persicae (green peach aphid), Dysaphis foeniculus, Aphis spiraecola, D. apiifolia, Hyadaphis foeniculi, Cavariella aegopodii, and H. coriandri. Non-colonizing aphid species that transmitted the virus, in order of decreasing effectiveness, included: Lipaphis erysimi, Hyseroneura setariae, Brevicoryne brassicae, Acrthosiphon kondoi, Sitobion miscanthi, Rhopalosiphum maidis, and R. padi.

Host range: Narrow – only carrots have been found infected in the field, but greenhouse studies in Australia have shown that CarVY can infect several other members of the Apiaceae, including anise, Bishop's weed, chervil (Anthriscus sylvestris), coriander, cumin, dill, and parsnip. CarVY did not infect celery, fennel, parsley, and several related herbs.

Carrot cultivar susceptibility: All carrot cultivars that have been tested in Australia have proven susceptible. Seed transmission: As stated above by Roger Jones, “exhaustive tests involving grow out of many thousands of seedlings from plants infected with the virus and testing the seedlings by ELISA failed to confirm that seed transmission occurs”. The Farmnote states that similar viruses belonging to the same virus family are seedborne at very low levels, but seed transmission of this virus has not been demonstrated.

Management recommendations: In areas where CarVY becomes established, the recommendations for managing the disease include:

  1. Avoid adjacent plantings of carrot, and grow non-host crops between carrot crops;
  2. Destroy volunteer carrots and plow residues into the ground after harvest;
  3. Monitor aphid populations and protect recently-planted carrot crops with approved insecticides if aphids are numberous.
  4. Use a “carrot-free” period in the growing season (this could be a difficulty in areas with biennial seed crops in the same areas as annual root crops).



  • Results of vegetable field trials in Carol Miles’ program at WSU Vancouver REU:
1)     Icebox watermelon production
2)     Winter lettuce production
3)     Alternatives to plastic mulch


        Riga, E., and Collins, H.P. 2004. Green manure effects on Meloidogyne chitwoodi and Paratrichodorus allius, economically important nematodes of potatoes in the Pacific Northwest of the USA. Agroindustria 3:321-322.
Biological & Cultural Tests:

        du Toit, L.J., and Pelter, G.Q. 2005. Susceptibility of storage onion cultivars to iris yellow spot in the Columbia Basin of Washington, 2004. B&C Tests 20:V006.
Fungicide & Nematicide Tests:

        du Toit, L.J., and Derie, M.L. 2005. Evaluation of Actigard, bactericides, and compost teas for control of bacterial blight in carrot seed crops, 2004. F&N Tests 60:V046.

        du Toit, L.J., and Derie, M.L. 2005. Evaluation of fungicides and compost teas for control of Botrytis scape and umbel blight in onion seed crops, 2004. F&N Tests 60:V045.

        du Toit, L.J., Derie, M.L., and Hernandez-Perez, P. 2005. Evaluation of fungicides for control of leaf spot in spinach seed crops, 2004. F&N Tests 60:V044.

        du Toit, L.J., Derie, M.L., and Hernandez-Perez, P. 2005. Evaluation of yield loss caused by leaf spot fungi in spinach seed crops, 2004. F&N Tests 60:V047.

        du Toit, L.J., Derie, M.L., and Morrison, R.H. 2005. Evaluation of fungicide seed treatments for control of black leg of cauliflower, 2004. F&N Tests 60:ST011.

        Gundersen, B. and Inglis, D. A. 2005. Evaluation of in-furrow treatments for control of pink rot on potato, 2004. F&N Tests 60.

        Inglis, D. A. and Gundersen, B. 2005. Evaluation of seed, in-furrow and foliar treatments for control of root rot on peas, 2003. F&N Tests 60.

Plant Disease: 
  • du Toit, L.J., Crowe, F.J., Derie, M.L., Simmons, R.B., and Pelter, G.Q. 2005. Bacterial blight in carrot seed crops in the Pacific Northwest
    . Plant Disease: in press.

    du Toit, L.J., Derie, M.L., and Hernandez-Perez, P. 2005. Verticillium wilt in spinach seed crops. Plant Disease 89:4-11.

  • du Toit, L.J., Derie, M.L., and Pelter, G.Q. 2004. Botrytis species in onion seed crops in Washington
    Plant Disease 88:1061-1068.

    du Toit, L.J., Pappu, H.R., Druffel, K.L., and Pelter, G.Q. 2004. Iris yellow spot virus in onion bulb and seed crops in Washington
    . Plant Disease 88:222.

    Ingham, R.E., Hamm, P.B., Riga, A., and Merrifield, K.J. 2005. First report of stunting and root rot of potato associated with Pratylenchus penetrans in the Columbia Basin of Washington. Plant Disease 89:207.

  • Johnson, D. A., Inglis, D. A., and Miller, J. S.  2004. Control of potato tuber rots caused by oomycetes with foliar applications of phosphorous acid. Plant Disease

  • Porter, L. D., Inglis, D. A., and Johnson, D. A. 2004. Identification and characterization of resistance to Phytophthora infestans in commercial potato cultivars and advanced breeding lines. Plant Disease 88:965-972.
Plant Health Progress
  • du Toit, L.J., Glawe, D.A., and Pelter, G.Q. 2004. First report of powdery mildew of onion (Allium cepa) caused by Leveillula taurica in the Pacific Northwest
    . Online. Plant Health Progress doi:10.1049/PHP-2004-1129-01-HN.

    , D.A., du Toit, L.J., and Pelter, G.Q. 2004. First report of powdery mildew on potato caused by Leveillula taurica in
    North America. Online. Plant Health Progress doi:10.1094/PHP-2004-1214-01-HN.
Abstracts for posters or oral presentations:

        Chilvers, M.I., du Toit, L.J., and Peever, T.L. 2005. RFLP differentiation of neck rot Botrytis spp. present in onion seed crops in Washington State, and development of a real-time PCR assay for detection of these fungi in onion seed. 23rd Fungal Genetics Conference, 15-20 March 2005, Pacific Grove, CA.

        Coyne, C. J., Grunwald, N. J., Inglis, D. A., McPhee, K. E., and Pilet-Nayel, M. L. 2004. Inheritance of Fusarium root rot resistance in pea using RILs. 5th European Grain Legume Conference, Dijon, France (Poster Abstract 7-11).

        Coyne, C. J., Watt, C., McManus, S., Grunwald, N. J., Inglis, D. A., McPhee, K. E., and Pilet-Nayel, M. L. 2004. Preliminary identification of QTL associated with Fusarium root rot resistance in pea. Poster 6067. Ann. Mtg. ASA-CSSA-SSSA, Seattle.
  • Glawe, D.A., Dugan, F.M., Cerkauskas, R.F., du Toit, L.J., Mohan, S.K., and Liu, Y. 2005. Leveillula taurica: An emerging plant pathogen in the Pacific Northwest
    Inoculum 56:in press
Glawe, D.A., Dugan, F.M., du Toit, L.J., Liu,Y., and Rogers, J.D. 2005. Leveillula taurica in Washington State. Annual Meeting of the Pacific Division of the APS, 28 June – 1 July 2005, Portland, OR. Phytopathology 95:accepted.
        Inglis, D. A. and Gundersen, B. 2004. Evaluation of seed, in-furrow and foliar treatments for control of damping-off and root rot on green pea. Ann. Wash. Tilth Mtg., Vancouver, WA (poster presentation).

        Hernandez-Perez, P., and du Toit, L.J. 2005. Efficacy of hot water and chlorine for eradication of Cladosporium variabile, Stemphylium botryosum, and
spp. from spinach seed. Phytopathology 95:S41.

        Hernandez-Perez, P., and du Toit, L.J. 2005. Prevalence of Cladosporium variabile and Stemphylium botryosum in commercial spinach seed, and the potential for seed transmission of these fungi. Phytopathology 95:S41.

        Lee, I., Bottner, K., Munyaneza, J., Davis, R., Croslin, J., du Toit, L., and Crosby, T. 2005. Carrot purple leaf: A new carrot disease associated with Spiroplasma citri and phytoplasmas in Washington. Phytopathology 95:S57.
(Please contact individual WSU Vegetable Pathology Team members if you would like further information on a specific paper.)

Our pages provide links to external sites for the convenience of users. WSU Extension does not manage these external sites, nor does Extension review, control, or take responsibility for the content of these sites. These external sites do not implicitly or explicitly represent official positions and policies of WSU Extension.

WSU Mount Vernon NWREC, 16650 State Route 536, Mount Vernon, WA 98273-4768, 360-848-6120
Contact Us: Lindsey du Toit and Carol Miles