University of Hawai‘i at Manoa
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Last updated on Friday, October 11, 2019     Make updates ->

Randall T  Hamasaki

Name :

Randall T Hamasaki

Title :

Co Extn Agent

Unit :

Department of Plant & Environmental Protection Sciences

Office :

Kamuela Extension Office

Address :

67-5189 Kamamalu Rd
                  Kamuela, HI 96743

Phone :

(808)887-7626

Fax :

(808)887-6182

E-mail :

rth@hawaii.edu

Website :

http://www.ctahr.hawaii.edu/peps

Specialties :

Vegetables, Tea, and Blueberries

Professional Prep/Appointments :


M.S. Entomology, University of Hawaii.  B.S. Agriculture, University of Hawaii.

Projects :


Commercial Edible Crops Extension
Distribution of a New Green Tea Cultivar for Hawaii Growers
Hawaii Integrated Pest Management Program for Diamondback Moth and Other Lepidopteran Pests of Crucifers
Real-time Optimization of Irrigation Scheduling for Farmlands in Hawaii, Guam, and American Samoa.
Improvement of Disease Resistance and Pest Resistance of Tropical Root Crops
Application of Macadamia Nut Husk as Organic Matter Source in Tillage Cropping Systems


Professional Interests :


Extension education and applied research for vegetables, herbs, blueberry and tea.

Publications :


  • Matsunaga, J.N., L.S. Roerk, and R.T. Hamasaki. 2019. Olive Fruit Fly Bactrocera oleae (Rossi) (Diptera: Tephritidae). New Pest Advisory No. 19-03. State of Hawaii, Department of Agriculture. https://hdoa.hawaii.gov/pi/files/2019/10/Bactrocera-oleae-OLFF-NPA.pdf
  • Olmedo-Velarde, A., A. Roy, C.A. Belanger, S. Watanabe, R.T. Hamasaki, V.A. Mavrodieva, M.K, Nakhla, and M.J. Melzer. 2019. First Report of Tomato Chlorotic Dwarf Viroid Infecting Greenhouse Tomato in Hawaii. Plant Disease 103 (5):1049.https://doi.org/10.1094/PDIS-08-18-1401-PDN
  • Hamasaki, R.T. and S.T. Nakamoto. 2018. In-Tray Procedure for Rooting Tea Cuttings. SCM-35. College of Tropical Agriculture and Human Resources, University of Hawaii at Manoa. https://www.ctahr.hawaii.edu/oc/freepubs/pdf/SCM-35.pdf
  • Hamasaki, R.T. and S. Nelson. 2018. Lettuce Downy Mildew in Hawaii. PD-115. College of Tropical Agriculture and Human Resources, University of Hawaii at Manoa. https://www.ctahr.hawaii.edu/oc/freepubs/pdf/PD-115.pdf
  • Hamasaki, R.T., A.M. Kawabata, J.N. Matsunaga, S. Chun, S.A. Wages and B.C. Bushe. 2018. Biltothrips minutus (Bhatti), Thysanoptera: Thripidae causing damage to various plants in Hawaii. IP-45. College of Tropical Agriculture and Human Resources, University of Hawaii at Manoa. https://www.ctahr.hawaii.edu/oc/freepubs/pdf/IP-45.pdf
  • Isele, E. and R.T. Hamasaki. 2018. Cucumber. HGV-17. College of Tropical Agriculture and Human Resources, University of Hawaii at Manoa. https://www.ctahr.hawaii.edu/oc/freepubs/pdf/HGV-17.pdf
  • Olmedo-Velarde, A., R.T. Hamasaki, B. Bushe, and M.J. Melzer. Tomato Chlorotic Dwarf Viroid. 2017. PD-113. College of Tropical Agriculture and Human Resources, University of Hawaii at Manoa. https://www.ctahr.hawaii.edu/oc/freepubs/pdf/PD-113.pdf
  • Green, K.J., M. Chikh-Ali, R.T. Hamasaki, M.J. Melzer, and A.V. Karasev. 2017. Potato virus Y (PVY) isolates from Physalis peruviana are unable to systemically infect potato or pepper and form a distinct new lineage within the PVYc strain group. Phytopathology 107 (11): 1433-1439. https://apsjournals.apsnet.org/doi/pdf/10.1094/PHYTO-04-17-0147-R
  • Hamasaki, Randall T., Andrea M. Kawabata and Stuart T. Nakamoto. 2017. Insect and Mite Pests of Blueberries in Hawaii. IP-42. College of Tropical Agriculture and Human Resources, University of Hawaii at Manoa. https://www.ctahr.hawaii.edu/oc/freepubs/pdf/IP-42.pdf
  • Miyasaka, Susan C., Randall T. Hamasaki, and Russell T. Nagata. 2017. Reflective Guide to Growing Olives for Oil Production in Hawai‘i. NPH-16. College of Tropical Agriculture and Human Resources, University of Hawaii at Manoa. https://www.ctahr.hawaii.edu/oc/freepubs/pdf/NPH-16.pdf
  • Motomura, Sharon, Alyssa Cho, Randall Hamasaki, Kiersten Akahoshi, Andrea Kawabata, Andrew Kawabata, and Stuart Nakamoto. 2016. Evaluation of pot size for greenhouse production of ‘Misty’ Southern highbush blueberry in Volcano, Hawaii. F_N-48. College of Tropical Agriculture and Human Resources, University of Hawaii at Manoa. https://www.ctahr.hawaii.edu/oc/freepubs/pdf/F_N-48.pdf
  • Hamasaki, Randall T., Takahiro Ino and Stuart T. Nakamoto. 2016. Green Tea Quality Evaluation: Identifying Common Defects. FST-65. College of Tropical Agriculture and Human Resources. University of Hawaii at Manoa. http://www.ctahr.hawaii.edu/oc/freepubs/pdf/FST-65.pdf
  • Miyasaka, Susan C. and Randall T. Hamasaki. 2016. Promising Olive Cultivars for Oil Production in Hawaii. HortTechnology 26(4): 497-506.  http://horttech.ashspublications.org/content/26/4/497.abstract
  • Hamasaki, Randall T. and Stuart T. Nakamoto. 2016. ‘Mealani’, A New Variety of Tea for Hawaii. NPH-15. College of Tropical Agriculture and Human Resources. University of Hawaii at Manoa. http://www.ctahr.hawaii.edu/oc/freepubs/pdf/NPH-15.pdf
  • Sugano, J.S.K., M.D.C. Diaz-Lyke, R.T. Hamasaki, S. Fukuda, R. Paull and S.T. Nakamoto. 2016. Papaya Maturity Chart: Proper Fruit Selection During Harvest Improves Market Value. College of Tropical Agriculture and Human Resources. University of Hawaii at Manoa. English: http://www.ctahr.hawaii.edu/oc/freepubs/pdf/Papaya_Ripening.ENG.1.pdf Ilokano: http://www.ctahr.hawaii.edu/oc/freepubs/pdf/Papaya_Ripening.ILO.1.pdf
  • Thorne, Mark S. and Randall T. Hamasaki. 2016. Management of Caterpillar Pests in Hawaii Pastures. 2016. PRM-12. College of Tropical Agriculture and Human Resources. University of Hawaii at Manoa. http://www.ctahr.hawaii.edu/oc/freepubs/pdf/PRM-12.pdf
  • Hamasaki, R.T., S.A. Motomura, and S.T. Nakamoto. 2015. Hawaii Tea Growers’ Survey 2014. NPH-14. College of Tropical Agriculture and Human Resources. University of Hawaii at Manoa. http://www.ctahr.hawaii.edu/oc/freepubs/pdf/NPH-14.pdf
  • Hamasaki, R.T., S.A. Motomura, M.J. Melzer and B.C. Bushe. 2015. Potato Virus Y: A Pathogen Associated With an Emerging Disease of Poha in Hawaii. PD-109. College of Tropical Agriculture and Human Resources. University of Hawaii at Manoa. http://www.ctahr.hawaii.edu/oc/freepubs/pdf/PD-109.pdf
  • Hamasaki, Randall, T., Sharon A. Motomura, Andrea M. Kawabata, Andrew F. Kawabata, Kiersten Akahoshi, and Stuart T. Nakamoto. 2015. Growing Blueberries for Home Production in Hawaii. Fruit, Nut, and Beverage Crops. F_N-46. College of Tropical Agriculture and Human Resources. University of Hawaii at Manoa. http://www.ctahr.hawaii.edu/oc/freepubs/pdf/F_N-46.pdf
  • Pant, Archana, Theodore J.K. Radovich, Koon-Hui Wang, N.V. Hue, Marla Fergerstrom, Randall Hamasaki, Matthew Wung, and Chris Robb. 2014. Performance and Plant-Available Nitrogen (PAN) Contribution of Cover Crops in High Elevations in Hawaii. Sustainable Agriculture SA-15, UHM College of Tropical Agriculture and Human Resources. http://www.ctahr.hawaii.edu/oc/freepubs/pdf/SA-15.pdf
  • Sugano, J., R. Hamasaki, E. Villalobos, M.Y. Chou, M. Wright, S. Fukuda, S. Swift, S. Ferreira, D. Tsuda, M. Diaz-Lyke, and S.T. Nakamoto. 2013. (Poster) Damage to Papaya Caused by Thrips parvispinus (Karny). College of Tropical Agriculture and Human Resources. University of Hawaii at Manoa. English: http://www.ctahr.hawaii.edu/oc/freepubs/pdf/Papaya_Thrips_poster.pdf Ilokano: http://www.ctahr.hawaii.edu/oc/freepubs/pdf/Papaya_Thrips.ILO.2.pdf
  • Sugano, J.S.K, M.D.C. Diaz-Lyke, R.T. Hamasaki, S. Fukuda, R. Paull, S.T. Nakamoto. 2013. (Poster). How to Minimize On-Farm Papaya Fruit Damage. College of Tropical Agriculture and Human Resources. University of Hawaii at Manoa. English: http://www.ctahr.hawaii.edu/oc/freepubs/pdf/Papaya_Harvest_poster.pdf Ilokano: http://www.ctahr.hawaii.edu/oc/freepubs/pdf/Papaya_Harvest_ILOC.1.pdf
  • Nakamoto, Stuart, Jie Gonsowski, Randall Hamasaki, Elyse Petersen, and Aurencio Seguritan. 2011. Hawaii-Grown Tea: A Market Feasibility Study. Honolulu, HI: University of Hawaii, College of Tropical Agriculture and Human Resources (CTAHR) and Pacific Asian Center for Entrepreneurship and E-Business (PACE), Shidler College of Business. http://www.ctahr.hawaii.edu/oc/freepubs/pdf/tea_2011.pdf
  • Kawabata, Andrew F., Jonathan L. Deenik, Randall T. Hamasaki, Joanne Lichty, and Stuart T. Nakamoto. 2011. Acidification of Volcanic Ash Soils From Maui and Hawaii Island for Blueberry and Tea Production. Soil and Crop Management. AS-5. http://www.ctahr.hawaii.edu/oc/freepubs/pdf/AS-5.pdf
  • Follett, Peter A., Francis T. Zee, Randall T. Hamasaki, Kim Hummer, and Stuart T. Nakamoto. 2011. Susceptibility of Low-Chill Blueberry Cultivars to Mediterranean Fruit Fly, Oriental Fruit Fly, and Melon Fly (Diptera: Tephritidae). J. Econ. Entomol. 104(2): 566-570.
  • Zee, Francis, Randall T. Hamasaki, Stuart T. Nakamoto, Lisa Keith, Kim Hummer, Barbara Reed, and Andrew Kawabata. 2010. Producing Potted Ornamental Ohelo. OF-50. http://www.ctahr.hawaii.edu/oc/freepubs/pdf/OF-50.pdf
  • Keith, L., L. Sugiyama, A. Strauss, R. Kai, F. Zee, R. Hamasaki, M. Yamasaki, and S Nakamoto. 2008. First Report of Leaf Rust of Blueberry Caused by Pucciniastrum vaccinii in Hawaii. Plant Disease 92 (11): 1590.
  • Yamasaki, Milton T., Randall T. Hamasaki, Dwight Sato, and Stuart T. Nakamoto. 2008. In-Ground Procedure for Rooting Tea Cuttings. Cooperative Extension Service, College of Tropical Agriculture and Human Resources.Soil and Crop Management. SCM-23. 4 pp. http://www.ctahr.hawaii.edu/oc/freepubs/pdf/SCM-23.pdf
  • Hamasaki, Randall T., Robin Shimabuku, and Stuart T. Nakamoto. 2008. Guide to Insect and Mite Pests of Tea (Camellia sinensis) in Hawaii. Cooperative Extension Service, College of Tropical Agriculture and Human Resources. Insect Pests. IP-28. 15 pp. http://www.ctahr.hawaii.edu/oc/freepubs/pdf/IP-28.pdf
  • Deenik, J., R. Hamasaki, R. Shimabuku, S. Nakamoto, and R. Uchida. 2007. Phosphorus Fertilizer Management for Romaine Lettuce Grown in Fertile Volcanic Ash Soils of Hawaii. Cooperative Extension Service, College of Tropical Agriculture and Human Resources. SCM-19. 3 pp. http://www.ctahr.hawaii.edu/oc/freepubs/pdf/SCM-19.pdf
  • Deenik, J., R. Hamasaki, R. Shimabuku, S. Nakamoto, and R. Uchida. 2006. Phosphorus Fertilizer Management for Head Cabbage. Cooperative Extension Service, College of Tropical Agriculture and Human Resources. SCM-16. 6 pp. https://www.ctahr.hawaii.edu/oc/freepubs/pdf/SCM-16.pdf
  • Zee, Francis, Kim Hummer, Wayne Nishijima, Russell Kai, Amy Strauss, Milton Yamasaki, and Randall T. Hamasaki. 2006. Preliminary Yields of Southern Highbush Blueberry in Waimea, Hawai’i. Cooperative Extension Service. College of Tropical Agriculture and Human Resources. F&N-12. 8 pp. https://www.ctahr.hawaii.edu/oc/freepubs/pdf/F_N-12.pdf
  • Borth, W.B., Fukuda, S.K., Hamasaki, R.T., Hu, J.S. and Almeida R.P.P. 2006. Detection, characterisation and transmission by Macrosteles leafhoppers of watercress yellows phytoplasma in Hawaii. Annals of Applied Biology 149: 357-363.
  • Silva, J.A., R. Hamasaki, R. Paull, R. Ogoshi, D. P. Bartholomew, S. Fukuda, N.V. Hue, G. Uehara, and G. Tsuji. 2006. Effects of Lime, Gypsum, and Basaltic Dust on the Calcium Nutrition and Fruit Quality of Pineapple. Acta Horticulturae 702: 123-131.
  • Fukuda, S., W. Borth, R. Almeida, R. Hamasaki, J. McHugh, R. Heu, B. Kumashiro, M. Kawate, D. Ogata and J. Sugano. 2004. How to Recognize Symptoms of Aster Yellows in Watercress. Cooperative Extension Service, College of Tropical Agriculture and Human Resources. IP-020. https://www.ctahr.hawaii.edu/oc/freepubs/pdf/IP-20.pdf
  • Heu, R.A., R.T. Hamasaki, J.A. Yalemar and J.S. Sugano. 2005. Pickleworm Diaphania nitidalis Cramer (Lepidoptera: Crambidae). New Pest Advisory No. 05-02. State of Hawaii, Department of Agriculture. https://hdoa.hawaii.gov/pi/files/2013/01/npa05-02-Pickleworm.pdf
  • Borth, W.B., Almeida, R.P.P., Fukuda, S.K., Hamasaki, R.T. and Hu, J.S. 2004. Phytoplasma disease of watercress in Hawaii. Phytopathology 94 (Supplement): S9.
  • Zee, Francis, Dwight Sato, Lisa Keith, Peter Follett, and Randall T. Hamasaki.  2003. Small-scale Tea Growing and Processing in Hawaii. NPH-9. Cooperative Extension Service, College of Tropical Agriculture and Human Resources. 16 pp. https://www.ctahr.hawaii.edu/oc/freepubs/pdf/NPH-9.pdf
  • Heu, R.A., B.R. Kumashiro, R.T. Hamasaki, and S.K. Fukuda. 2003. Watercress Leafhopper Macrosteles sp. nr. severini Hamilton (Homoptera: Cicadellidae). New Pest Advisory No. 02-01. State of Hawaii, Department of Agriculture. https://hdoa.hawaii.gov/pi/files/2013/01/npa02-01-wcleafhopper.pdf
  • Miyasaka, Susan C., Randall T. Hamasaki, and Ramon S. de la Pena. July 2002. Nutrient Deficiencies and Excesses in Taro. Soil and Crop Management. SCM-4.Cooperative Extension Service. College of Tropical Agriculture and Human Resources. 14 pp. https://www.ctahr.hawaii.edu/oc/freepubs/pdf/SCM-4.pdf
  • Borth, W.B., R. T. Hamasaki, D. Ogata, S. K. Fukuda, and J. S. Hu. 2002. First Report of Phytoplasmas Infecting Watercress in Hawaii. Plant Disease 86(3): 331.
  • Nishina, Melvin, Francis Zee, Richard Ebesu, Alton Arakaki, Randall Hamasaki, Steven Fukuda, Norman Nagata, Chian Leng Chia, Wayne Nishijima, Ronald Mau, and Raymond Uchida. 2000. Papaya Production in Hawaii. F &N-3. Cooperative Extension Service. College of Tropical Agriculture and Human Resources. 8 pp. https://www.ctahr.hawaii.edu/oc/freepubs/pdf/F_N-3.pdf
  • Sakuoka, Richard, Randall T. Hamasaki, Robin Shimabuku, and Alton Arakaki. 2000. Lettuce for the Home Garden. CTAHR Cooperative Extension Service Home Garden Vegetable HGV-2. 2 pp. https://www.ctahr.hawaii.edu/oc/freepubs/pdf/HGV-2.pdf
  • Valenzuela, Hector, R., Ted Goo, Randall T. Hamasaki, and Ted Radovich. 2000. The effect of bone meal on the yield of jicama, Pachyrhizus erosus, in Oahu, Hawaii. Proc. Fla. State Hort. Soc. 113:222-226.
  • Hamasaki, Randall T., Hector R. Valenzuela, and Robin S. Shimabuku. 1999. Bulb Onion Production In Hawaii. College of Tropical Agriculture and Human Resources. 52 pp. https://www.ctahr.hawaii.edu/oc/freepubs/pdf/onion_production.pdf
  • Sipes, Brent S., Alton S. Arakaki, Donald P. Schmitt, and Randall T. Hamasaki.1999.Root-Knot Nematode Management in Tropical Cropping Systems with Organic Products.Journal of Sustainable Agriculture 15: 69-76.
  • Moy, J.H., B. Chinnasri, B.S. Sipes, D.P. Schmitt, R.T. Hamasaki, E.F. Mersino, and R.M. Yamakawa. 1999. Radiation Disinfection or Disinfestation of Nematodes, Aphids, Mites, Thrips, and Other Pests on Food Plant Materials: Evaluation for Effectiveness and Product Quality.In Irradiation as a Quarantine Treatment of Arthropod Pests, Proc. Final Research Coordination Meeting, Honolulu, Hawaii, International Atomic Energy Agency, Vienna, pp. 105-113.https://inis.iaea.org/collection/NCLCollectionStore/_Public/30/023/30023910.pdf?r=1&r=1
  • Hue, N.V., J. A. Silva, G. Uehara, R. T. Hamasaki, R. Uchida, and P. Bunn.  1998.  Managing Manganese Toxicity in Former Sugarcane Soils on Oahu.  Cooperative Extension Service, College of Tropical Agriculture and Human Resources.  Soil and Crop Management (SCM-1). https://www.ctahr.hawaii.edu/oc/freepubs/pdf/SCM-1.pdf
  • Hamasaki, Randall T.  1998.  ‘UH Sweet Basil’ A New Basil Cultivar Tolerant of Fusarium Wilt.  Cooperative Extension Service, College of Tropical Agriculture & Human Resources, University of Hawaii at Manoa.  New Plants for Hawaii (NPH-3). https://www.ctahr.hawaii.edu/oc/freepubs/pdf/NPH-3.pdf
  • Hue, N.V., J.A. Silva, G. Uehara, R.T. Hamasaki, R. Uchida, and P. Bunn.1998.Manganese Toxicity in Acid Soils in Hawaii.P. 238. In Agronomy abstracts. ASA, CSSA, and ASA. Madison, WI.
  • Sato, D.M., A.H. Hara, R.F.L. Mau, D.M. Tsuda, and R.T. Hamasaki.  1997.  Taro Root Aphid.  Cooperative Extension Service, College of Tropical Agriculture and Human Resources.  Insect Pests, IP-1. https://www.ctahr.hawaii.edu/oc/freepubs/pdf/IP-1.pdf
  • Takeda, K. Y., S. K. Fukuda, and R. Hamasaki.1996.“Koba” Green Onion.J. Haw. Pac. Agri. 6: 49-50.
  • Uchida, J. Y., C. Y. Kadooka, and R. T. Hamasaki.1995.First Report of Fusarium wilt of Basil in Hawaii.Plant Disease 80: 105.
  • Hu, J. S., Z. C. Wu, S. Luis, R. Hamasaki, and K. Barry.1994.Detection of geminiviruses in Hawaii.Phytopathology84: 1072.
  • Hu, J. S.,S. Luis, K. Barry, M. Wang, and R. T. Hamasaki.1994.First Report of a Geminivirus in Hawaii.Plant Disease78: 641.
  • Hamasaki, Randall T., Hector R. Valenzuela, Dick M. Tsuda, and Janice Y. Uchida.  1994.  Fresh Basil Production Guidelines for Hawaii.  HITAHR, College of Tropical Agriculture and Human Resources, University of Hawaii, Research Extension Series 154. https://www.ctahr.hawaii.edu/oc/freepubs/pdf/RES-154.pdf
  • Valenzuela, Hector R., Randall T. Hamasaki, and Steven K. Fukuda.  1994.  Field Cucumber Production Guidelines for Hawaii.  HITAHR, College of Tropical Agriculture and Human Resources, University of Hawaii, Research Extension Series 151. https://www.ctahr.hawaii.edu/oc/freepubs/pdf/RES-151.pdf
  • Valenzuela, H., R.T. Hamasaki, and T.M. Hori.  1993.  Field Tomato Production Guidelines for Hawaii.  Hawaii Institute of Tropical Agriculture and Human Resources.  Research Extension Series 141. https://www.ctahr.hawaii.edu/oc/freepubs/pdf/RES-141.pdf
  • Hamasaki, R. T. and R. A. Heu.1991.Calacarus brionese Keifer.Notes and Exhibitions.Proc. Haw. Ent. Soc.31: 30.
  • Cho, J.J., R.F.L. Mau, R.T. Hamasaki, and D. Gonsalves.1988.Detection of Tomato Spotted Wilt Virus in Individual Thrips by Enzyme-Linked Immunosorbent Assay.Phytopathology 78: 1348-1352.