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Krista C. Shellie, Lisa Neven and Steve Drake

Phytosanitary restrictions for insect pests can interfere with the marketing of fresh sweet cherries (Prunus avium L.). The objective of this research was to compare the quality of controlled atmosphere temperature treated (CAT) sweet cherries to methyl bromide fumigated cherries and non-heated, non-fumigated control fruit. Two CAT doses were evaluated: a 25-min exposure to 47 °C (117 °F) that heated the cherry center to 46 °C (115 °F), and a 40-min exposure to 45 °C (113 °F) that heated the cherries to a center temperature of 44 °C (111 °F). These heat doses approximated a heat dose that provides quarantine security against codling moth (Cydia pomonella Lw.) and western cherry fruit fly (Rhagoletis cingulata Lw.). An atmosphere of 1 kPa oxygen and 15 kPa carbon dioxide was established inside the treatment chamber for 21 min prior to heating. The influence on fruit quality of hydrocooling prior to the CAT treatment, cooling after treatment, and 2 weeks of cold storage after treatment in air or controlled atmosphere was evaluated. Each CAT dose was replicated four times using freshly harvested, `Bing' sweet cherries acquired from similar grower lots. Quality attributes evaluated included: stem and fruit color, firmness, soluble solids concentration, titratable acidity, decay, and sensory evaluations. Hydrocooling prior to treatment, cooling method after heating and storage atmosphere had no significant influence on cherry quality after cold storage. The stem color of fumigated cherries was less green after storage than CAT treated cherries or untreated, control cherries. Cherries heated for 25 min were rated after cold storage by untrained panelists as similar to non-heated, non-fumigated control fruit. Heated cherries and methyl bromide fumigated cherries were less firm after cold storage than control fruit.

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Krista C. Shellie and Robert L. Mangan

Navel orange [Citrus sinensis (L.) Osbeck] was exposed to moist, forced air at 46 °C for up to 4.5 hours or 50 °C for 2 hours, or immersed for 3 hours in water at 46 °C. Quality attributes of heated and nonheated fruit were compared after 4 weeks of storage at 7 °C and 1 week at 23 °C. The flavor of oranges immersed in water was rated significantly inferior to fruit heated in air and fruit that were not heated. Oranges immersed in hot water also developed a higher incidence of decay during storage than oranges heated in air or nonheated control fruit. The flavor of oranges exposed to moist, forced air at 46 °C for up to 4.5 hours was rated by preference panelists as similar to nonheated controls, even though heated fruit had a significantly lower amount of titratable acidity and a higher ratio of sugar to acid. Fruit exposed to high-temperature forced air developed less decay during subsequent storage than nonheated control fruit. Texas `N33' navel oranges tolerated exposure to forced air at 46 °C for up to 4.5 hours without deleterious effects on fruit market quality.

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Krista C. Shellie and Robert L. Mangan

`Dancy' tangerines (Citrus reticulata Blanco) were harvested after color break and exposed to high-temperature forced air (HTFA) at 45C for 3.5 or 4 h to kill Mexican fruit fly [Anastrepha ludens (Loew)] larvae. Heat-treated and control fruit were stored subsequently for 2 weeks at 4C. Tangerines harvested after color break (naturally degreened) tolerated exposure to HTFA in a similar fashion as tangerines harvested before color break and degreened by postharvest exposure to ethylene. Titratable acidity (TA) was significantly lower after heat treatments. Flavor, soluble solids concentration, external appearance, incidence of decay, percent juice yield, percent weight change, and flavedo color of heat-treated fruit were not different from nonheat-treated, control fruit. Exposure to HTFA is a viable alternative to methyl bromide for disinfestation of `Dancy' tangerine.

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Krista C. Shellie and George L. Hosfield

Genetic and environmental interactions for bean cooking time, water absorption, and protein content were estimated with 10 dry bean (Phaseolus vulgaris L.) cultivars grown at three locations in Rwanda, Africa, during five consecutive harvests. The genotypic variance component was larger than genotype × environment variance components for the cooking time index and percent water absorption. No significant genotypic effect was observed for seed protein content. The phenotypic correlation (-0.37) between the cooking time index and percent water absorption was not strong enough to justify the use of water absorption as an indirect selection method for cooking time. The most efficient allocation of resources to evaluate the cooking time of common bean cultivars with a 25-pin bar-drop cooker was four field replications over two harvests at two locations. Water absorption was evaluated most efficiently with four field replications over two harvests at a single location.

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Krista C. Shellie, Robert L. Mangan and Sam J. Ingle

The objective of this research was to investigate whether a controlled atmosphere established inside a high temperature forced air chamber could enhance the mortality of the most heat-resistant life stage of Mexican fruit fly larvae (Anastrepha ludens Loew) and thereby reduce the amount of time grapefruit (Citrus paradisi Macf.) harvested from Mexican fruit fly-infested regions must be exposed to high-temperature forced air to achieve quarantine security. The mortality of third instar larvae treated on diet was significantly higher after exposure to 1% oxygen or 1% oxygen enriched with 20% carbon dioxide than it was in either air or air enriched with 20% oxygen. Reducing the amount of oxygen in air from 21% to 1% during forced air heating at 46°C, reduced the exposure time required for 100% kill of larvae inside artificially infested grapefruit from 5 hours to 3.5 hours. Inconsistent fruit quality results warrant further study to optimize controlled atmosphere conditions during heating. Based upon relative levels of carbon dioxide inside the grapefruit during heating, fruit respiration during heating in 1% oxygen was lower than during heating in air. Results from this research suggest that reducing the amount of oxygen in a high temperature forced air chamber during heating can reduce the amount of time fruit must be exposed to heat for quarantine security against Mexican fruit fly.

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Krista C. Shellie, Robert D. Meyer and T. Erik Mirkov

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Krista C. Shellie, Michael J. Firko and Robert L. Mangan

Early season degreened `Dancy' tangerines (Citrus reticulata Blanco) were size graded and subjected to high-temperature, moist, forced-air (HTMFA) treatments using air at 45, 46, or 48C for 0, 1, 2, 3, or 4 hours. The phytotoxic response of fruit to the beat treatments was evaluated immediately after treatment and weekly during 3 weeks of cold (4C) storage. Mortality of nonfeeding, third instar Mexican fruit fly [(Anastrepha ludens (Loew)] larvae was estimated for each time-temperature heat treatment combination in water baths that simulated the heating and cooling profiles of heat-treated fruit. Unacceptable phytotoxic symptoms, such as inferior flavor and darkened flavedo tissue, were observed when fruit was treated at 46 or 48C. Fruit heated with 45C forced moist air had flavedo color change(ΔL*)percent juice yield, soluble solids concentration, and flavor ratings that were statistically similar to ratings for unheated, control fruit. An HTMFA treatment of 3 or 4 hours at 45, 46, or 48C and subsequent cooling was sufficient to kill 100% of naked larvae in water baths. Market quality of fruit was maintained after a 4-hour HTMFA treatment at 45C, and 100% mortality of naked larvae occurred after 3 hours at 45C.

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Imed E. Dami, Shouxin Li, Patricia A. Bowen, Carl P. Bogdanoff, Krista C. Shellie and Jim Willwerth

Economic loss due to cold weather events is a major constraint to winegrape (Vitis vinifera) production and wine-related industries where extreme and/or fluctuating winter temperatures induce injury and require remedial retraining and replanting increases production costs and lowers yield and fruit quality. The purpose of this study was to determine whether a foliar application of abscisic acid (ABA) could increase the freezing tolerance (FT) of field-grown, ‘Chardonnay’ winegrape and whether its effectiveness can be influenced by the phenological timing of the application. Mature ‘Chardonnay’ grapevines were treated with a foliar application of ABA at a concentration of 500 mg·L−1 at vine phenological stages corresponding to 50% véraison, postvéraison, and postharvest. Results from field trial sites located in four distinct winegrape production regions in the United States (Idaho and Ohio) and Canada (British Columbia and Ontario) showed that foliar application of ABA increased bud FT, primarily during autumn cold acclimation. Foliar ABA application had no consistent influence on bud FT in midwinter or during spring deacclimation, or on percent budburst in spring. Vine phenological stage at the time of ABA foliar application influenced ABA effectiveness, although results were inconsistent among locations. At most locations, applications made at véraison or postvéraison were more effective than applications made postharvest. No phytotoxic response or adverse changes in yield or berry composition were detected in response to ABA application. The consistent increase in bud FT during autumn cold acclimation observed at all trial locations in this study indicates that foliar ABA, applied at véraison or postvéraison, can reduce the risk of economic loss due to cold injury in production regions with frequent early autumn cold weather events.