Division of Agriculture and Natural Resources
Division of Agriculture and Natural Resources
Division of Agriculture and Natural Resources
University of California
Division of Agriculture and Natural Resources

Steven A. Tjosvold

Photo of Steven A. Tjosvold
Farm Advisor Environmental horticulture
Cooperative Extension Santa Cruz County
1430 Freedom Boulevard, Suite E
Watsonville, CA 95076-2796
(831) 763-8013
satjosvold@ucanr.edu Create VCard

Also in:
Monterey County

Biography

Position Description:

Responsible for the planning and implementation of educational and field research programs in floriculture, nursery production, turf management, and landscape horticulture in Santa Cruz and Monterey counties.

Farm Advisor 1983 (Santa Cruz and Monterey counties)

Farm Advisor Intern 1980 - 1983  (Alameda, Orange, and San Bernardino counties)


Awards and honors:

  • 1997 UC ANR Distinguished Service Award
    Outstanding Team Work
  • 2004 UC ANR Distinguished Service Award
    Outstanding Extension
  • 2004 UC ANR Distinguished Service Award
    Outstanding Team Work
  • 2006 UC ANR Distinguished Service Award
    Outstanding Team Work
  • 2008 Western Extension Directors’ Awards of Excellence
    for contributions to a team effort of the Farm Water Quality Planning Project
  • 2012 California Association of Nurseries and Garden Center Award
    for Outstanding Research.
  • 2015 Western Extension Directors Association Award of Excellence
    for contributions to a team effort that addressed Sudden Oak Death.

 

Education

M.S. , UC Davis. 1980
B.S. , UC Davis. 1977

Specialty

Environmental horticulture

Areas of Expertise (click to see all ANR academics with this expertise)

Bibliography

Peer Reviewed

  • Koike, S.; Tjosvold, S. (2014). Diagnosing Plant Problems. Container Nursery Production and Business Management.J. Newman. Richmond, CA, University of California Agriculture and Natural Resources.
  • Tjosvold, S; Murray, N.; Epstein, M.; Sage, G.; Gilligan, T. (2014). Field Identification Guide for Light Brown Apple Moth in California Nurseries. University of California Agriculture and Natural Resources.
  • Mathews, D.; Becker, J.; Tjosvold, S. (2014). Plant Diseases. Container Nursery Production and Business Management.J. Newman. Richmond, CA, University of California Agriculture and Natural Resources. Publication 3540
  • Kabashima, J.; Bethke, J.; Tjosvold, S (2014). The impact of invasive pests on the nursery industry. Container Nursery Production and Business Management.J. Newman. Richmond, CA, University of California Agricultura and Natural Resources. Publication 2540
  • Karlik, J.; Tjosvold, S; Dreistadt, S. (2013). Clearwing Moths. Pest Note. University of California Agriculture and Natural Resources. Publication 7477
  • Tjosvold, S.; Chambers, D.; Chastagner, G.; Elliott, M.; Fitchner, E. (2013). Effect of Environmental Conditions and Lesion AGe on Sporulation of Phytophthora ramorum on California Bay, Rhododendron, and Camellia. Sudden Oak Death Fourth Science Symposium, U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station, Albany, CA.
  • Tjosvold, S.; Chambers, D.; Chastagner, G.; Elliott, M.; Fitchner, E. (2013). Effect of Fungicides and Biocontrol Agents on Inoculum Production and Persistence of Phytophthora ramorum. Fourth Sudden Oak Death Science Symposium, U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station, Albany, CA.
  • Chastagner, G.; Elliott, M.; Tjosvold, S; Shishkoff, N. (2013). Risk of Root-to-Root Spread of Phytophthora ramorum in Ornamental Production Nurseries. Sudden Oak Death Fourth Science Symposium, U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station, Albany, CA.
  • Tjosvold, Steve A.; Chambers, D.; Mori, S. (2012). Effect of Environmental Conditions and Lesion Age on Sporulation of Phytophthora ramorum on California Bay, Rhododendron, and Camellia. Proceedings of the Fifth Sudden Oak Death Science Symposium, Petaluma, CA.
  • Koike, S.; Tjosvold, S.; Matthews, D. (2012). Floriculture and Ornamental Nurseries, Disease Section. UC IPM Pest Management Guidelines.
  • Kabashima, J.N.; Bethke, J.A.; Tjosvold, Steve A. (2012). The impact of invasive pests on the nursery industry. Container Nursery Production and Business Management.J. Newman. Richmond, CA, Univ. of Calif. Agric. and Nat. Resour.
  • Faber, B.; Gaskell, M.; Baameur, A.; Bolda, M.; Tjosvold, S.; De la Fuente, M. (2011). "Growing Crops". Small Farm Handbook.L. Tourte and B. Faber. Oakland, California, University of California, Division of Agriculture and Natural Resources. Publication 3526: 101-124.
  • Matthews, D.; Becker, O.; Tjosvold, Steve A. (2011). Plant Diseases. Container Nursery Production and Business Management.J. Newman. Richmond, CA, Univ. of Calif. Agric. and Nat. Resour.
  • Tjosvold, S.; Chambers, D.; Fitchner, E. (2010). Importance of Rainfall and Sprinkler Irrigation in Supporting Sporulation, Spread of Inoculum in Runoff –Water and New Infections of Phytophthora ramorum under Field Condition. Sudden Oak Death Fourth Science Symposium.
  • Swain, S.; Tjosvold, S.; Dreistadt, S. (2009). California Oakworm. Pest Notes. University of California Agriculturre and Natural Resources. Publication 7422
  • Tjosvold, S.; Chambers, D.; Fitchner, E.; Koike, S.; Mori, S. (2009). "Disease risk of potting media infested with Phytophthora ramorum under nursery conditions." Plant Disease 93: 371-376.
  • Tjosvold, S.; Chambers, D.; Koike, S.; Mori, S. (2008). "Disease on Nursery Stock as Affected by Environmental Factors and Seasonal Inoculum Levels of Phytophthora ramorum in Stream Water Used for Irrigation." Plant Disease 92: 1566-1573.
  • Tjosvold, S.; Koike, S.; Chambers, D. (2008) Evaluation of fungicides for the control of Phytophthora ramorum infecting Rhododendron, Camellia, Pieris, and Viburnum. Plant Health Progress DOI: 10.1094/php-2008-0208-01-rs
  • Tjosvold, S.; Chambers, D.; Blomquist, C. (2008). Seasonal Symptom Expression, Laboratory Detection Success, and Sporulation Potential of Phytophthora ramorum on Rhododendron and Camellia. Sudden Oak Death Second Science Symposium: The State of Our Knowledge (Proceedings.), Pacific Southwest Research Station, Forest Service, United States Department of Agriculture.
  • Casey, C.; Newman, J.; Robb, K.; Tjosvold, S.; MacDonald, J.; Parrella, M. (2007). "IPM program successful in California greenhouse cut roses." California Agriculture 61(2): 71-78.
  • Tjosvold, S.; Chambers, D.; Koike, S. (2006). Evaluation of fungicides for the control of Phytophthora ramorum infecting Rhododendron, Camellia, Viburnum, and Pieris. Sudden Oak Death Second Science Symposium: The State of Our Knowledge, Pacific Southwest Research Station, Forest Service, U.S. Department of Agriculture.
  • Tjosvold, S.; Chambers, D.; Thomas, S.; Blomquist, C. (2006) First Report of Phytophthora ramorum infecting Camellia flower buds in North America. Plant Health Progress DOI: 10.1094/php-2006-0825-01-br
  • Carne-Cavagnaro, V.; Robb, K.; Tjosvold, S; et al., (2005). Demonstrating reduced-risk practices for control of important pests of Gerbera jamesonii grown as cut flower. Bulletin-OILB/SROP. 28: 35.
  • Tjosvold, S.; Chambers, D.; Fitchner, E. (2005). Epidemiology of Phytophthora ramorum Infecting Rhododendrons under Simulated Nursery Conditions. Sudden Oak Death Second Symposium: The State of Our Knowledge, Monterey, CA, Pacific Southwest Research Station, Forest Service, U.S. Department of Agriculture.
  • Tjosvold, S.; Buermeyer, K.; Blomquit, C.; Frankel, S. (2005). Nursery Guide for Diseases of Phytophthora ramorum on Ornamentals: Diagnosis and Management. Division of Agricultural and Natural Sciences Publications. Publication #8156
  • Koike, S.; Browne, G.; Bhat, R.; Lee, R.; Tjosvold, S.; Burermeyer, K. (2005). "Phytophthora Leaf Spot and Foliar Blight of Pieris japonica Caused by Phytophthora citricola in California." Plant Disease 89: 1013.
  • Koike, S.; Fogle, D.; Tjosvold, S.; King, A. (2004). "Downy mildew caused by Peronospora radii on marguerite daisy (Argyranthemum frutescens) in California." Plant Disease: 1163.
  • Schochow, M.; Tjosvold, S.; Ploeg, A. (2004). "Host status of Lisianthus ‘Mariachi Lime Green’ for three species of root-knot nematodes." HortScience 39(1): 120-123.
  • Koike, S.; Tjosvold, S.; Groenwalkd, J.; Crous, P. (2003). "First report of a Leaf Spot Disease of Bells-of-Ireland (Moluccella laevis) Caused by Cercospora apii in California." Plant Disease 87(2): 203.
  • Tjosvold, S.; Koike, S. (2003). "First report of downy mildew on Delphinium caused by Peronospora ficariae in California." Plant Disease 87(12): 1540.
  • Karlik, J.; Tjosvold, S. (2003). Integrated pest management. Encylopedia of Rose Science.T. Debener, S. Gudin and A. Roberts. Elsevier Publishing.: 466-472.
  • Tjosvold, S.; Karlik, J. (2003). Mites. Encylopedia of Rose Science.T. Debener, S. Gudin and A. Roberts. Elsevier Publishing.: 431-437.
  • Tjosvold, S.; Chambers, S.; Tse, J.; Davidson, J.; Garbelotto, M.; Koike, S. (2002). Evaluation of a novel diagnostic procedure to detect the presence of Phytophthora ramorum by sampling ooze from infected cankers. Sudden Oak Death, a Science Symposium: The State of Our Knowledge. Monterey, CA,
  • Tjosvold, S.; Koike, S. (2002). "First occurrence of Downy Mildew on Digitalis purpurea (Common Foxglove), caused by Peronospora digitalidis, in California and the United States." Plant Disease 86(10): 1176.
  • Koike, S.; Tjosvold, S.; Groenwalkd, J.; Crous, P. (2002). "First report of a leaf spot disease of bells of Ireland (Moluccella laevis) in California caused by Cercopsproa apii." Plant Disease
  • Tjosvold, S.; Chambers, S.; Davidson, J.; Rizzo, D. (2002). Incidence of Phytophthora ramorum inoculum found in soil collected from a hiking trail and hikers’ shoes in a California park. Sudden Oak Death, a Science Symposium: The State of Our Knowledge. Monterey, CA,
  • Tjosvold, S.; Chambers, S.; Davidson, J.; Rizzo, D. (2002). Incidence of Phytophthora ramorum inoculum found in streams running through areas of high incidence of Sudden Oak Death in Santa Cruz County. Sudden Oak Death, a Science Symposium: The State of Our Knowledge. Monterey, CA,
  • Davidson, J.; Rizzo, D.; Garbelotto, M.; Tjosvold, S.; Slaughter, G. (2002). Phytophthora ramorum and sudden oak death in California: II. Transmission and survival. USDA Forest Service General Technical Reports. PSW-GTR-184
  • Garbelotto, M.; Rizzo, David M.; Hayden, K.; Meija-Chang, M.; Davidson, J.; Tjosvold, S. (2002). Phytophthora ramorum and sudden oak death in California: III. Preliminary studies in pathogen genetics. USDA Forest Service General Technical Reports. PSW-GTR-184
  • McPherson, B.; Rizzo, D.; Garbelotto, M.; Syihra, P.; Wood, D.; Storer, A.; Kelly, N.; Palkovsky, N.; Tjosvold, S.; Standiford, R.; Koike, S. (2002). "Sudden oak death in California." Pest Notes Publication 7498
  • Tjosvold, S.; Koike, S.; Davidson, J.; Rizzo, D. (2002). Susceptibility of Azalea (Rhododendron) to Phytophthora ramorum. Sudden Oak Death, a Science Symposium: The State of Our Knowledge. Monterey, CA,
  • Davidson, J.; Wickland, A.; Morse, A.; Tjosvold, S.; Chambers, S.; Jensen, C..; Slaughter, G.; Garbelotto, M.; Rizzo, D. (2002). Transmission of Phytophthora ramorum in Coast Live Oak woodlands. Sudden Oak Death, a Science Symposium: The State of Our Knowledge. Monterey, CA,
  • Koike, S.; Tjosvold, S. (2001). "A blight disease of dill in California caused by Itersonilia perplexans." Plant Disease 85(7)
  • Tjosvold, S. (2001). "Effect of Bending on Production and Quality of Commercial Greenhouse Roses in Field Soil." Acta Horticulturae 547: 299-302.
  • Tjosvold, S. (2001). Effect of miticides on two-spotted spider mites and predatory mites on field-grown nursery roses. Tips on Selecting Pest Management Strategies. Ohio Florist Publications.: 45-46.
  • Tjosvold, S.; Koike, S. (2001). "Evaluation of reduced risk and other biorational fungicides on the control of powdery mildew on greenhouse roses." Acta Horticulturae 547: 59-67.
  • Tjosvold, S.; Chaney, W. (2001). "Evaluation of Reduced Risk and Other Biorational Miticides on the Control of Spider Mites (Tetranychus urticae)." Acta Horticulturae 547: 93-96.
  • Tjosvold, S.; Koike, S.; Chaney, W. (2001). Evaluation of Reduced Risk and Other Biorational Pesticides on Control of Spider Mites (Tetranychus urticae) and Powdery Mildew of Rose (Sphaerotheca pannosa). 2001 CORF Research Tour.
  • Oki, L.; Lieth, J.; Tjosvold, S. (2001). "Irrigation based on soil moisture tension increases rose productivity and flower quality." Acta Horticulturae 547: 213-219.
  • Elmore, C.; McDonald, J.; Tjosvold, S.; Zasada, I. (2001). Pest control alternatives to methyl bromide in field-grown flowers. Greensboro, NC, Weed Science Society of America.
  • Garbelotto, M.; Rizzo, D.; Hayden, K.; Meija-Chang, M.; Davidson, J.; Tjosvold, S. (2001). Studies in the genetics of Phytophthora sp. nov. associated with sudden oak death. Fifth Symposium on Oak Woodland, San Diego, California.
  • Davidson, J.; Rizzo, D.; Garbelotto, M.; Tjosvold, S.; Slaughter, G. (2001). Transmission and Survival Of Sudden Oak Death Phytophthora Species Novus. Fifth Symposium on Oak Woodland, San Diego, California.
  • Tjosvold, S.; Elmore, C.; McDonald, J. (2000). Alternatives to methyl bromide in floricultural crops- project update. California Weed Science Society.
  • Tjosvold, S. (2000). Evaluation of reduced risk and other biorational pesticides on the control of spider mites. Central Coast Family Farm Report. University of California Cooperative Extension. October 2000
  • Parrella, M.; Casey, C.; Newman, J.; Robb, K.; Tjosvold, S. (2000). Glasshouses: integrating natural enemy release and biologicial pesticides for insect pest management in roses. California Conference on Biological Control II, Riverside, California.
  • Tjosvold, S. (2000). Powdery mildew management strategies. Sixteenth Conference on Insect & Disease Management on Ornamentals, Society of American Florists.
  • Elmore, C.; Roncoroni, J.; McDonald, J.; Bolan, L.; Zasada, I.; Ferris, H.; Tjosvold, S. (2000). Solarization and biofumigation for field-grown flowers. 2000 International Research Conference on Methyl Bromide Alternatives and Emissions Reductions (Proceedings).
  • Elmore, C.; Tjosvold, S.; Roncoroni, J. (2000). Using additives to enhance weed management with soil solarization. Fifteenth International Congress for Plastics in Agriculture and the Twenty-Ninth National Agricultural Plastics Congress.
  • Elmore, C.; Roncoroni, J.; McDonald, J.; Bolan, L.; Zasada, I.; Ferris, H.; Tjosvold, S. (2000). Weed, soil pathogen, and nematode control in microplots. 2000 International Research Conference on Methyl Bromide Alternatives and Emissions Reductions.
  • Koike, S.; Henderson, D.; Crous, P.; Schoch, C.; Bag XI, P.; Tjosvold, S. (1999). "A New Root and Crown Rot Disease of Heath in California Caused by Cylindrocladium pauciramosum." Plant Disease 85: 589.
  • Tjosvold, S. (1999). Effect of Miticides on Two-spotted Spider Mites and Predatory Mites on Field-grown Nursery Roses. Selecting Pest Management Strategies. Ohio Florist Association.
  • Schulbach, K.; Tjosvold, S.; Kasapligil, D. (1999). "Improving Irrigation Systems Conserves Water in Greenhouse-grown Cut Flowers." California Agriculture
  • Koike, S.; Henderson, D.; Tjosvold, S.; Simmons, E. (1999). "Outbreak of Leaf Spot of Saponaria Caused by Alternaria saponariae in California." Plant Disease 83: 694.
  • Dahlsten, D.; Rowney, D.; Cooper, W.; Chaney, W.; Robb, K.; Tjosvold, S.; Lane, P. (1998). Biological Control of the Blue Gum Psyllid in California. California Conference on Biological Control. University of California, Berkeley,
  • Murphy, B.; Newman, J.; Morisawa, T.; Tjosvold, S.; Parrella, M. (1998). "Fungal Pathogen Controls Thrips in Greenhouse Flowers." California Agriculture 52(3)
  • Dahlsten, D.; Tassen, R; Tjosvold, S.; Rowney, D.; Chaney, W.; Bianchi, M.; Cooper, W.; Robb, K.; Lane, P. (1998). "Parasitoid Wasp Controls Blue Gum Psyllid." California Agriculture
  • Newman, J.; Robb, K.; Tjosvold, S.; King, A. (1997). Training Scouts and Developing Demonstration Sites to Promote IPM Programs for Ornamental Crops. Entomological Society of America.
  • Dahlsten, D.; Robb, K.; Tassen, R.; Cooper, W.; Chaney, W.; Robb, K.; Tjosvold, S.; Bianchi, M.; Lane, P. (1996). Biological control of the blue gum psyllid, Ctenartytainae eucalypti (Maskell) (Homoptera: Psyllidae), in California. XX International Congress of Entomology, Firenze, Italy.
  • Dahlsten, D.; Rowney, D.; Tassen, R.; Cooper, W.; Chaney, W.; Robb, K.; Tjosvold, S.; Bianchi, M.; Lane, P. (1996). "Blue Gum Psyllid." Hort Script 20
  • Cooper, W.; Chaney, W.; Robb, K.; Tjosvold, S.; Bianchi, M.; Lane, P. (1996). "Blue Gum Psyllid." Hort Script 20
  • Tjosvold, S.; Chaney, W. (1996). Effect of insecticides on control of blue gum psyllid infesting commercial cut eucalyptus, 1991. Arthropod Management Tests. 21: 371-372.
  • Tjosvold, S.; Greene, I.; Colbert, D. (1996). Effect of spray methods and miticides on control of twospotted spider mites infesting commercial greenhouse roses, 1994. Arthropod Management Tests. 21: 361.
  • Tjosvold, S.; Greene, I.; Colbert, D. (1996). Effect of spray methods and miticides on control of twospotted spider mites infesting commercial greenhouse roses, 1995. Arthropod Management Tests. 21: 362.
  • Tjosvold, S.; Greene, I. (1996). Evaluation of fungicides for control of powdery mildew on rose, 1994. Fungicide and Nematicide Tests. 51
  • Koike, S.; Tjosvold, S.; Cookset, D.; Azad, H. (1995). "A bacterial leaf disease of lavender caused by Xanthomonas campestris." Plant Disease 78: 859.
  • Tjosvold, S. (1995). Evaluation of soil fungicides for control of carnation fusarium wilt. Fungicide and Nematicide Tests. 50
  • Saenz, G.; Koike, S.; Tjosvold, S.; Greene, I. (1995). "First report of powdery mildew on carnation in California." Plant Disease 79: 426.
  • Koike, S.; Tjosvold, S.; Greene, I. (1995). "Powdery mildew of Eustoma caused by Leveillula taurica in California." Plant Disease 79: 426.
  • Tjosvold, S.; Wu, M.; Reid, M. (1995). Reduction of post-production quality loss in potted miniature roses. Acta Horticulturae. 405, Postharvest Physiology of Ornamental Plants
  • Tjosvold, S.; Greene, I.; Raabe, R. (1995). Resistance of commercial carnation cultivars to rust disease, 1994. Biological and Cultural Tests. 10
  • Tjosvold, S.; Wu, M.; Reid, M. (1994). "Reduction of Post-production Quality Loss in Potted Miniature Roses." HortScience 29(4): 293-294.
  • Isakeit, T.; Weinhold, A.; Hancock, J.; Schroth, M.; Tjosvold, S. (1993). Counteraction of the Biological Vacuum Created by Soil Fumigation and Steaming. Innovations in Landscape Pest Management. University of California Division of Agricultural and Natural Resources.: 46-48.
  • Tjosvold, S.; Ali, A. (1993). Effect of postharvest naled and sulfotep fumigation on western flower thrips infesting carnation. The 1993 International Conference on Thysanoptera. Thrips Biology and Mangagement: Proceedings of the 1993 International Conference on Thysanoptera, NATO ASI Series A: Life Sciences.
  • Isakeit, T.; Tjosvold, S.; Ferri, M.; Weinhold, A.; Schroth, M.; Hancock, J. (1992). Evaluation of several soil amendments added after fumigation with methyl bromide to control fusarium wilt of carnation. Biological and Chemical tests. American Phytopathological Society Press.
  • Isakeit, T.; Tjosvold, S.; Weinhold, A.; Schroth, M.; Hancock, J. (1991). Evaluation of several soil amendments added after fumigation with methyl bromide to control fusarium oxysporum. Biological and Chemical tests. American Phytopathological Society Press.
  • Tjosvold, S.; Schulbach, K. (1991). "How to Reduce Water Use and Maximize Yields in Greenhouse Roses." California Agriculture 45(3)
  • Raabe, R.; Tjosvold, S. (1991). "Rust and Leafspot Control on Dutch Iris." California Plant Pathology 89
  • Tjosvold, S. (1988). Borers in Landscape Trees and Shrubs. U.C. Extension. leaflet #21316
  • Tjosvold, S. (1988). "Mildew and Height Control On Potted Floribunda Rose Cultivars." California Plant Pathology 79
  • Tjosvold, S.; McCain, A. (1988). "Treatment of pitch canker on Monterey pine with fungisol injection." Journal of Arboriculture 14(5)
  • Henry, J.; Tjosvold, S.; Gibeault, V. (1988). "Zoysiagrass establishment." California Turfgrass Culture 38(#1 and 2)
  • McCain, A.; Koehler, C.; Tjosvold, S. (1987). "Pitch Canker Threatens California Pines." California Agriculture 41(#11 and, 12)
  • Burger, D.; Hartin, J.; Hodel, D.; Lukuszewski, T.; Tjosvold, S.; Wagner, S. (1987). "Water Use in California'™s Ornamental Nurseries." California Agriculture 49(#9 and 10)
  • Tjosvold, S.; Raabe, R. (1986). "Heterosporium Leaf Spot Control on Dutch Iris." California Plant Pathology 73
  • Tjosvold, S.; Raabe, R. (1986). "Powdery Mildew Control in Greenhouse Royalty™ Roses." California Plant Pathology 72
  • Tjosvold, S. (1982). Borers in Landscape Trees and Shrubs. University of California, Cooperative Extension. leaflet #21316
  • Tjosvold, S. (1982). Controlling Damping-Off in the Home Garden. University of California, Cooperative Extension. leaflet #21299
  • Tjosvold, S.; McHenry, J. (1981). How to Kill Unwanted Trees, Shrubs and Resprouting Stumps in the landscape. University of California, Cooperative Extension. leaflet #7166

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