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Plant Pest Diagnostics Center

Dan Opgenorth

Dr. Dan C. Opgenorth

retired Senior Plant Pathologist

Plant Pest Diagnostics Branch, California Department of Food & Agriculture
3294 Meadowview Road, Sacramento, CA 95832-1448, U.S.A.
916-262-1123 office, 916-262-1190 fax, dopgenorth@cdfa.ca.gov


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Curriculum vitae


  • Doctor of Philosophy (Plant Pathology) - University of California, Riverside, 1980: GPA 3.7.
  • Master of Science (Plant Pathology) - University of California, Riverside, 1973: GPA 3.7.
  • Bachelor of Science with Honors (Biochemistry) - University of Wisconsin, Madison, 1969: GPA 3.5.
  • Certified Plant Pathologist #24946 and Member of the Certification Board American Society of Agronomy
My scientific education is broadly based including chemistry, biochemistry, statistics, pest management, natural science (weather and climate), entomology, soils and plant pathology (bacteriology, nematology, mycology and virology ). Experience includes research in all classical areas of plant pathology. I graduated with honors from the Univ. of Wisconsin and was a National Defense Title IV Fellow at the Univ. of Calif. Riverside.


  • Worked with U.C. Farm Advisors and Researchers at Parlier concerning the detection of Corn Stunt Spiroplasma using ELISA and PCR techniques on Plant and Insect samples.
  • Development of Real-Time PCR with a USDA cooperator, for rapid detection of significant regulatory pathogens at Federal Port Facilities in California (Citrus Canker).
  • Participation in NATO Exchange program with Macedonia to train foreign scientists.
  • Maintenance of the Bacterial Culture Collection acquired from U. C. Berkeley Department of Plant Pathology.
  • Development of Rep-PCR for identification of Plant Pathogenic Bacteria and use of PCR for the detection of Phytoplasma.
  • Production of Monoclonal Antibodies for the detection of Prunus Necrotic Ringspot Virus. (Patents with U. C. Berkeley)
  • Establishment of an ELISA Laboratory at CDFA to test for regulatory plant viruses; including contract work with biotechnology companies and grant work on stone fruit virus diseases.
  • Chairman of the California Plant Disease Conference: responsible for the organization of seminars concerning Pesticide Use, Grape Pathology, Seed Pathology and Stone Fruit Virus Diseases.
  • Responsible for all laboratory work concerning the detection of genetically altered ice minus bacteria (Frost Ban) released into the environment on strawberry test plots in California.
  • Negotiated contractual arrangements with scientists using specific gene probes to positively identify the genetically altered bacteria.
  • Graduate Research Assistant conducting thesis research on Fusarium Yellows of Celery. (Major Professor: Dr. Robert Endo)
  • USDA Extension Specialist operating the Plant Disease Diagnostic Clinic at the Univ. of Wisconsin Madison. Supervisor: Dr. Gayle Worf
  • Research Associate at Cornell Univ. Conducting field work on the epidemiology and control of Fire Blight. Supervisor Dr. Steven Beer.
  • Ph.D. Thesis: Sources of Resistance to Fusarium Yellows of Celery; studies of chlamydospore formation and germination; effects of inoculum density and pH on disease development.


  • Involved in the training and supervision of all Research Associates and Seasonal Employees working in the CDFA Bacteriology Laboratory.
  • Teaching Assistant in a basic Plant Pathology course for pest management majors under supervision of Professor Donald C. Erwin.


  • Diagnostic Plant Pathology; Antique Auto Restoration; Motorcycling; Scouting; Little League; bicycling, skiing, camping, hiking etc. Member American Phytopathological Society and Buick Club of America


  • American Phytopathological Society
  • Buick Club of America.


  • U. S. Army, 1970-72. Stationed at Letterman General Hospital San Francisco in the pathology section doing directed research using electron microscopy.


  • Dr. Conrad Krass; Principal Staff Pathologist at CDFA (916) 654-1009
  • Mr. William Callison Branch Chief CDFA (916) 262-1100
  • Dr. Bruce Kirkpatric U. C. Davis Plant Path (510) 445-6214
  • Dr. Charles Summers  Kearney Agricultural Center (559) 646- 6500.

Literature Published

  1. Worf, G. L. and D. C. Opgenorth. 1974. Chemical control of Snow Mold (Typhula spp.) on turf. American Phytopathological Society Fungicide-Nematicide .Results for 1974.
  2. Beer, S. v. and D. C. Opgenorth. 1976. Erwinia amylovora on flreblight canker surfaces and blossoms in relation to disease occurrence. Phytopathology 66: 311-317.
  3. Opgenorth, D. C. and R. M. Endo. 1979. Sources of resistance to Fusarium Yellows of Celery. Plant Disease Reporter 63: 165-169.
  4. Opgenorth, D. C. and R. M. Endo. 1981. Competitive Saprophytic Ability (CSA) of Fusarium oxysporium f.sp. apii. Phytopathology 71: 246
  5. Lai, M., D. Opgenorth and J. B. White. 1982. Occurrence of Pseudomonas corrugata on Tomato in California. Plant Disease 67: 110.112.
  6. Opgenorth, D.C. 1982. Storage Rot of California Grown Kiwifruit. Plant Disease 67: 382-383.
  7. Michailides, T. J., J. M. Ogawa and D. C. Opgenorth. 1987. Shift of Monilinia spp. and distribution of isolates sensitive and resistant to Benomyl in California Prune and Apricot orchards. Plant Disease 71: 893-896.
  8. Braun, A. L. and D. C. Opgenorth: 1987. Comparative detectability of potato leafroll virus, potato virus X and potato virus S using enzyme-linked immunosorbant assy (ELISA) and serologically specific electron microscopy (SSEM). American Potato Journal 64: 205-209
  9. Opgenorth, D. C. and J. Smith. 1989. ELISA testing program for stone fruit viruses initiated in California. Phytopathology 1989
  10. Opgenorth, D. C.. and I. Smith. 1989. Production ofmonoc1ona1 antibodies to strains of Prunus Necrotic Ringspot Virus. Phytopathology 1989.
  11. Opgenorth, D. C., I. White and P. Gunnell. 1989. Strawberry Anthracnose in California. California Plant Pest and Disease Report (Sept-Dec) 1989.
  12. Opgenorth, D. C. and J.White. 1991. Hainesia Leaf Spot on Strawberry. California Plant Pest and Disease Report (Ian-May) 1991.
  13. Opgenorth, D. C. and J. White. 1991. Freeway Daisy (Osteospermum fructicosum) as host for Lettuce Mosaic Virus. Plant Disease 75: 751.
  14. Opgenorth, D. C. Alexander Karu and J. Smith. 1991. Monoclonal Antibodies for identification of Prunus Necrotic Ringspot Virus and Related Stone Fruit Viruses (Licensing Disclosure for Patent); U. C. Berkeley Office of Technology Licensing Invention and Technology. 1991.
  15. Opgenorth, D. C.. and J. White. 1992. Pear-Juniper Rust. Ca. Plant Pest and Dis. Report. Opgenorth, D. C. 1993. Olive Knot and Oleander Gall. Ca. Plant Pest and Dis. Report.
  16. Opgenorth, D. C. Sauber, and I. King 1993. First Report of Westeria Gall in California. California Plant Pest and Disease Report (Oct-Dec)
  17. Opgenorth, D. C., Connolly, K. and L. Braun. 1994. Bacterial Leaf Spot Unique to Manzanita sp. (Arctostaphylous densiflorus var. Howard McMinn). Ca. Plant Pest and Dis. Report.
  18. Opgenorth, D. C. 1994. Potato (common) Scab. Ca. Plant Pest and Dis. Report.
  19. Opgenorth, D. C. 1994. Drippy Nut Disease. Ca. Plant Pest and Dis. Report.
  20. Opgenorth, D. C., V Takikawa, Y ., M. Hendson and E. Clark. 1994. First Report of Bacterial Gall of Westeria sinensis caused by Erwinia herbicola pv. millettiae in California. PlantDisease 78: 1217.
  21. Opgenorth, D. C. 1995. Bacterial Fruit Blotch of Watermelon. Ca Plant Pest and ills. Report.
  22. Opgenorth, D. C. and C. Smart 1996. Identification of Xanthomonas fragariae Field Isolates by Rep-PCR Genomic Fingerprinting. Plant Disease 80: 868-873.
  23. Opgenorth, D. C. 1998. Bacterial Canker of Tomato. Ca. Plant Pest and Dis. Report.
  24. Louws, F. I., C. M. .Medina-Mora, J. Bell, C. D. Smart, Opgenorth, D. C., C. A. Ishimaru, M. K. Hausbeck, F. J. de Bruijn and D. W. Fulbright. 1998. Rep-PCR Mediated Genetic Fingerprinting is a Highly Discriminatory Method to Differentiate Subspecies of Clavibacter michiganensis. Phytopathology 88: 862-868.
  25. Schaad, N.W., D. C. Opgenorth and P. Gaush. 2002 Real-Time Polymerase Chain Reaction for one-Hour On-Site Diagnosis of Pierces Disease of Grape in Early Season Asymptomatic Vines. Phytopathology 92: 721-727.
  26. Schaad, N.W., D. Opgenorth. M. D. Petrillo, M. A. Abdelshife and T. Tedla. 2003. Evaluation of a On-Site, One –houe Real Time PCR Assay for Detecting the Citrus Canker Bacterium in Plant Samples at Port Facilities. APS Poster at Annual Meetings 2003.
  27. Summers, C. A., A. S. Newton and D. C. Opgenorth. 2004. Overwintering of Corn Leafhopper, Dalbulus maidis (Homoptera: Cicadellidae), and Spiroplasma kunkelii (Mycoplasmatales: Spiroplasmataceae) in Californias San Joaquin Valley. Journal of Environmental Entomology 33: No. 6 pp1644-1651.
  28. Wei. W., D. C. Opgenorth, R. E. Davis., and Y. Zaho. 2006. Characterization of a Novel Adhesion Gene and Design of a Real-Time Polymerase Chain Reaction for Rapid, Sensitive and Specific Detection of Spiroplasma kunkelii Phytopathology (in press)