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United States Department of Agriculture

Agricultural Research Service

Marisa Wall

Center Director

Marisa Wall

Contact Information

U.S. Pacific Basin Agricultural Research Center
64 Nowelo St.
Hilo, Hawaii 96720 
Ph: (808) 959-4343
Fax: (808) 959-5470


via ARIS System


  • B.S. Horticulture, Pennsylvania State University, 1982
  • M.S., Horticulture, University of Maryland, 1986
  • Ph.D., Horticulture, University of Maryland, 1989

Academic Positions

  • 1984-1989, Research Assistant, University of Maryland, College Park, MD
  • 1990-1996, Assistant Professor, Dept. Agronomy and Horticulture, New Mexico State University, Las Cruces, NM
  • 1996-2000, Associate Professor, Dept. Agronomy and Horticulture, New Mexico State University, Las Cruces, NM
  • 1998, Visiting Professor, Dept. Molecular Plant Physiology, University of Hawaii at Manoa, Honolulu, HI
  • 2001, Professor, Dept. Agronomy and Horticulture, New Mexico State University, Las Cruces, NM
  • 2001-present, Research Food Technologist (Postharvest Physiology), USDA-ARS, U.S. Pacific Basin Agricultural Research Center, Hilo, HI

Research Accomplishments

I have been leading research programs in the areas of postharvest physiology, vegetable breeding, and crop production for over 22 years. My areas of expertise include postharvest physiology of horticultural crops, biochemical quality analyses, and quarantine treatment of fresh commodities. Prior to joining ARS, I was Professor of Horticulture at New Mexico State University where I initiated the first programs in sweet onion breeding and postharvest physiology, with supporting teaching and extension activities. My current research is focused on postharvest physiology, quarantine treatment and export, and food technology for tropical crops, but my unique interdisciplinary experience enables me to lead research programs that encompass an entire production and postharvest system, from the seed to the consumer.

Quality of tropical crops following irradiation treatment
Irradiation can be used as a postharvest treatment to control quarantine insect pests for export of fresh fruit and vegetables to markets where they command premium prices. The economic viability of irradiation as a quarantine treatment improves if a diversity of crops can be treated. My research is focused on defining the radiotolerance limits for high-value, tropical crops (sweet potatoes, bananas and dragon fruit), and mixtures of tropical fruit. I have determined the compositional, sensory and storage quality of these crops following quarantine irradiation treatment, and elucidated the preharvest and physiological conditions that impact radiotolerance. The research supported the USDA-APHIS landmark rule accepting generic irradiation doses that accelerated the use of irradiation quarantine treatments for specific crops and greatly expanded exports. Hawaii's specialty crop exporters rapidly adopted the APHIS rule and now confidently irradiate and market over 20 million pounds annually.

Tropical fruit entering irradiation facility             Dragon fruit following irradiation treatment

Macadamia nut biochemistry and processing quality
Three major quality defects of macadamia nuts are gray kernel disorder, internal browning after roasting, and off-flavor development (oxidation and rancidity) during storage. My research has defined the biochemical and physical factors that contribute to kernel browning and oxidation, and established the preharvest and processing conditions under which these disorders manifest. Our lab quantified the phytochemicals, tocotrienols and squalene, in several cultivars of macadamia nuts grown in three microclimates, and identified cultivars with superior oxidative stability, enabling longer term storage. We also proved that a bacteria (Enterobacter cloacae) causes gray kernel disorder and established the environmental conditions optimal for disease development. My research provided the first understanding of the impact of initial kernel composition on post-processing quality, and demonstrated the importance of well-controlled processing conditions on macadamia kernel quality. The results have been used by the macadamia industry to optimize harvest and processing steps to enhance quality.

Internal browning of macadamia nuts Grey kernel disorder

Tropical fruit nutritional composition
Following the decline of sugarcane, Hawaii's agricultural base shifted to diversified small farms producing exotic tropical crops. New specialty fruit orchards are being planted annually and market supply is expected to increase greatly as trees reach full production. My research established precise compositional analyses for cultivars of five tropical fruits (banana, papaya, lychee, longan, and rambutan) grown in different micro-climates and soil types. The analyses were the most specific and sensitive determination of vitamin and mineral concentrations to date for tropical fruit. The fruit composition data is used to market these exotic fruit and to evaluate diets for nutritional adequacy.

Banana bunches at harvestFresh PapayaFresh rambutans

Papaya cultivars with resistance to food safety pathogens
Development of value-added products is necessary to sustain the papaya industry. Marketing of minimally processed papayas has been limited by coliform bacterial counts of enteric pathogens (Enterobacter cloacae and E. sakazakii) that cause internal yellowing disease. E. cloacae andE. sakazakii direct affect the quality and safety of papaya products. Our team developed a robust, accurate method for evaluating resistance to E. cloacae, and identified a new bacterial pathogen (E. sakazakii) as a cause of atypical internal yellowing symptoms on papaya for the first time. We also identified IY-resistant papaya cultivars, and then established the nutritional and microbial quality for fresh-cut and frozen papaya cubes prepared from these cultivars. The use of IY-resistant varieties improves the food safety of papaya, opening global markets for these value-added products.

Postharvest practices to improve tropical fruit quality
Postharvest practices to manage diseases, improve fruit quality, and extend the shelf-life of longans and rambutans were identified. The most suitable packaging systems were established for maintaining postharvest quality under optimum temperatures, as well as under fluctuating temperature regimes commonly experienced during the postharvest chain.In related research, we are investigating modified atmosphere packaging of fresh papaya for potential marine shipment to export markets.Adoption of a better packaging system for specialty fruit does not require a change in field practices, but can reduce postharvest quality problems which have been major constraints during export and marketing.

The Hamakua Plan for sustainable agriculture and energy
Hawaii imports over 85% of its food, and depends on imported petroleum to meet 89% of its energy needs. Even a small reduction in fuel or feed costs, or an increase in food production or value, would increase farm profitability substantially. The Hamakua Region Pilot Program is a model for sustainable agriculture and renewable energy for rural communities, and aims to transform a former sugarcane community into the "breadbasket of Hawaii" via a comprehensive approach that integrates technologies, processes, and people. The Hamakua Plan was developed by PBARC scientists and community stakeholders, and has three components (agricultural research, renewable energy, and community development) that comprise a zero-waste strategy to decrease the U.S. Pacific Basin's reliance on imported food, fuel, feed and fertilizer. My expertise encompasses complete production and postharvest systems (from seed to consumer) for high-value crops, and I have assumed major responsibility for implementing the agricultural research and energy portions of the plan. I am directing research on the conversion of regional feedstock to biofuel using heterotrophic algae, and on development of value-added products from tropical crops.

Service, Leadership and Participation in Professional Activities:

  • Consulting Editor, Journal American Society for Horticultural Science (2004-present)
  • Outstanding Researcher Awards Committee (2008-2013); Publications Committee (2000-2013); Horticulture Hall of Fame Committee (2010); Vegetable Publication Awards Committee (1997-1998); Public Relations Committee (1992-1994), American Society for Horticultural Science
  • Major advisor for 7 M.S. students and 3 Ph.D. students. Co-advisor for 2 Ph.D. students
  • Chair, NM Commission for Higher Education Graduate Research Awards Committee
  • USDA-ARS-PPQ science advisory panel for 'Sharwil' avocado exports
  • International Atomic Energy Commission (IAEA) training program for postharvest quality of irradiated fresh fruits and vegetables
  • Review panel for US-AID funded Horticultural Collaborative Research Support Program

Honors, Awards, Achievements and Recognition:

  • Federal Laboratory Consortium Award for Excellence in Technology Transfer, 2010, for implementation of phytosanitary irradiation treatment protocols for tropical fruit
  • Best Poster Award, 2007, Australasian Postharvest Conference, Terrigal, Australia
  • Outstanding Contribution Award, 2001, New Mexico Chile Pepper Task Force, for outstanding contribution to the advancement of mechanical harvesting of chile peppers, and for leadership and dedication that have greatly enhanced the chile industry
  • Distinguished Research Award, 1998, College of Agriculture and Home Economics, New Mexico State University
  • Honorary State FFA Degree, New Mexico, 1997, for outstanding service to the Future Farmers of America
  • Northeast Region Research Paper Award, 1989, American Society for Horticultural Science
  • Leland E. and Catherine B. Scott Award, 1987, Excellence in Graduate Study Award, Department of Horticulture, University of Maryland
  • Member, Sigma Xi Honor Society
  • Member, Gamma Sigma Delta Honor Society
  • Member, Pi Alpha Xi Honor Society

Last Modified: 8/12/2016
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