Membership in graduate groups: Plant Biology and Horticulture

The focus of my research and extension program is the postharvest physiology and handling of apples, pears, cherries, cling peaches, prunes, bushberries and strawberries as well as almonds and walnuts. In addition to studies on harvest maturity, storage conditions and quality measurements, my program will be focusing on developing alternatives to chemicals used postharvest for control of decay, physiological disorders, and insect quarantine treatments.

Current Research Activities

1. Use of SmartFresh (1-MCP) on Bartlett pears and California apples. We have been exploring the effects of using SmartFresh on California grown apples to maintain quality in storage. We have been developing treatment protocols for Bartlett pears including the effects of 1-MCP concentration, maturity of the pears at harvest, and delays after harvest before application of 1-MCP on the response of fruit to 1-MCP. Use of SmartFresh on pears is more challenging than for apples because the fruit must ripen prior to consumption.
2. Effect of storage temperature and ethylene on the post-storage quality of Bartlett pears. The post-storage quality of Bartlett pears is evaluated after storing at -1, 0, 1, and 2 degrees Celcius (30, 32, 34 and 36 degrees Farenheit) with 0, 1 or 10 ppm ethylene.
3. Methods to reduce skin browning of Bartlett pears. We are exploring a number of antioxidants to determine their ability to reduce the susceptibility of Bartlett pears to skin browning from surface abrasions. A rapid test to determine the susceptibility of the fruit to abrasion-induced browning is also under development.
4. Radio frequency heating to control insects in harvested fruits and nuts. Exposing fruits and nuts to radio frequency energy provides for very fast heating to temperatures lethal to many insect pests (50 to 55C). We are determining the temperatures and exposure times required to kill economically important insect species, and evaluating the effects on product quality of efficacious treatments. We have a protocol to control navel orangeworm, codling moth and Indianmeal moth in walnuts and are developing protocols for almonds and pistachios for the same pests. The fresh fruit we are working on include apples and sweet cherries to control codling moth, and control of various fruit fly species in citrus. This research is in collaboration with Judy Johnson at USDA ARS Fresno, CA, Juming Tang and Shaojin Wang with Washington State University, Jim Hansen with USDA ARS in Wapato, WA, and Guy Hallman with USDA ARS Weslaco, TX.
5. Control of arthropod pests on harvested table grapes. We are exploring a new fumigant, ethyl formate, to control various insect and mite species on harvested table grapes. Pest mortality and grape quality following treatment are under evaluation. In addition, we are testing a surfactant for control of arthropod pests on table grapes as well.

• Wszelaki, A.L. and E.J. Mitcham. 2002. Effect of combinations of hot water dips, biological control and controlled atmospheres for control of gray mold on harvested strawberries. Postharvest Biol. Technol. (in press).
• Wang, S, Tang, J, J.A. Johnson, E. Mitcham, J.D. Hansen, R.P. Cavalieri, J. Bower, and B. Biasi. 2002. Process protocols based on radio frequency energy to control field and storage pests in in-shell walnuts. Postharvest Biol. Technol. (in press)
• Clayton, M., W.V. Biasi, I.T. Agar, S.M. Southwick and E.J. Mitcham. 2002. Postharvest quality of 'Bing' cherries following preharvest treatment with hydrogen cyanimide, calcium ammonium nitrate, or gibberellic acid. HortScience (in press).
• Wszelaki, A.L. and E.J. Mitcham. 2002. Effect of combinations of hot water dips, biological control and controlled atmospheres for control of gray mold on harvested strawberrry. Postharvest Biol. Technol. (in press).
• Zhou, S., R.S. Criddle, and E.J. Mitcham. 2001. Metabolic response of Platynota stultana pupae under and after extended treatment with elevated CO2 and reduced O2 concentrations. J. Insect Physiol. 47:401-409.
• Volz, R.K., W.V. Biasi, J.A. Grant, and E.J. Mitcham. 1998. Prediction of controlled atmosphere-induced flesh browning in ‘Fuji’ apple. Postharvest Biol. Technol. 13:97-107.
• Mitcham, E.J., M. Clayton and W.V. Biasi. 1998. Comparison of devices for measuring cherry fruit firmness. HortScience 33:723-727.
• Abdallah, A.Y., M.I. Gil, W. Biasi, and E.J. Mitcham. 1997. Inhibition of superficial scald in apples by wounding: changes in lipids and phenolics. Postharvest Biol. Technol. 12:203-212.
• Mitcham, E. J., S. Zhou and V. Bikoba. 1997. Controlled atmospheres for quarantine control of three pests of table grape. J. Econ. Entomol. 90:1360-1370.
• Ahumada, M.H., E.J. Mitcham and D.G. Moore. 1996. Postharvest quality of 'Thompson Seedless' table grapes after insecticidal controlled atmosphere treatments. HortScience 31:833-836.