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J. Liu, C. Stevens, V.A. Khan, J.Y. Lu, C.L. Wilson, O. Adeyeye, M.K. Kabwe, L. Pusey, E. Chalutz, T. Sultana, and S. Droby

The application of low hormetic low-dose ultraviolet light (WV-C, 254 nm) on fruits and vegetables to stimulate beneficial responses is a new method for controlling storage rots and extending the shelf-life of fruits and vegetables. The present study was aimed at treating tomatoes (lycopersicon esculentum) with different UV-C dosages (1.3 to 40 KJ/m2) to induce resistance to black mold (Alternaria alternata), gray mold (Boytris cinerea), and Rhizopus soft rot (Rhizopus stolonifer). Thesediseases were effectively reduced when tomatoes were artificially inoculated following UV-C irradiation UV-C treated tomatoes were firmer in texture and less red in color than the control tomatoes, indicating a delay in ripening. Slower ripening and resistsace to storage rots of tomatoes are probably related. The positive effect of UVC on tomatoes decreased as treatments were performed at stages of increased ripeness.

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Jennifer R. DeEll and Robert K. Prange

This paper reports preliminary results on the postharvest quality and storage characteristics of several scab-resistant apple cultivars. `Novaspy', `Moira', `Priscilla', `Novamac', `Nova Easygro', `Prima', and `Macfree' were stored for 3 months at 3C in air or standard controlled atmosphere (CA; 4.5% CO2 and 2.5% O2) in 1990 and for 4 months at 0C in air, standard CA, or low-O, CA (LO; 1.5% CO2 and 1.5% O2) in 1991. `Moira', `Prima', and `Priscilla' had very limited storage life. `Moira' was susceptible to bitterpit, scald, core browning, vascular breakdown, and storage rots. `Prima' was susceptible to core browning and vascular breakdown and had a high incidence of storage rots in air storage. `Priscilla' had several defects as a result of insect damage and was susceptible to bitterpit and scald. `Novaspy' stored very well and had virtually no physiological disorders or storage rots. `Novamac, `Nova Easygro', and `Macfree' developed few storage rots and were essentially at the end of their storage life after 4 months, regardless of storage conditions. Firmness in `Novamac' decreased substantially in all storage atmospheres, while `Nova Easygro' and `Macfree' were susceptible to core browning and scald.

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Rosa Marina Arvayo-Ortiz, Sergio Garza-Ortega, and Elhadi M. Yahia

Winter squash are grown in northwestern Mexico for export to distant markets. During transport, fruits deteriorate and develop fungal rots. Squash (Cucurbita maxima Duch. `Delica') was given hot-water dips at 50C for 0, 3, 6, 9, and 12 min and stored at 10 and 20C with 75% RH for 4, 8, and 12 weeks. The highest weight loss (11.3%) was in fruits without hot water treatment stored at 20C for 12 weeks—weight losses were 3.6%, 7.2%, and 10.2% in the 4-, 8-, and 12-week storage periods, respectively. At 10C, the weight losses were 3.4%, 6.8%, and 7.6% for the same periods, respectively. ß-carotene content increased from 36.2 to 54.2 mg/100 g after 4 and 8 weeks of storage, respectively, but declined to 42.8 mg/100 g after 12 weeks. Chlorophyll content decreased as temperature and storage period increased, changing from 16.7 to 10.8 mg·liter-1 at 10 and 20C and from 16.9 to 15.8 mg·liter-1 and 8.8 mg·liter-1 at 4, 8, and 12 weeks, respectively. Fruits had decay caused by Rhizopus and Aspergillus. Weight loss, ß-carotene and chlorophyll contents, and decay were not affected by length of hot-water treatment. General appearance was better in fruits stored at 10 than at 20C.

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Jennifer R. DeEll, Jennifer T. Ayres, and Dennis P. Murr

testing was determined using a hand-held temperature-compensated refractometer (Fisher Scientific, Nepean, Ont.). After storage, the incidence of core browning, internal browning, and storage rot were determined as a percentage of fruit with the problem

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Jennifer DeEll and Behrouz Ehsani-Moghaddam

in ‘McIntosh’ and ‘Empire’ apples ( DeEll and Ehsani-Moghaddam, 2012b ). No CO 2 injury was observed in ‘Spartan’ apples. Storage rots were greatest after six months of air storage and 1-MCP treatments usually reduced the incidence regardless of the

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C. Stevens, C. L. Wilson, J. Y. Lu, V. A. Khan, E. Chalutz, M. K. Kabwe, Z. Haung, S. Droby, and L. Pusey

Low doses of ultraviolet light (254nm UV–C) irradiation reduced postharvest rots of pome, stone and citrus fruits. Brown rot (Monilinia fructicola) of `Elberta' and `Loring' peaches was significantly reduced by UV–C. Alternaria rot (Alternaria spp.) and bitter rot (Colletotrichum spp.) the principal storage rots of `Golden Delicious apples showed significant reduction following UV–C treatment. Further application of UV–C was effective in controlling green mold rot (Penicillium digitatum) of `Dancy' Tangerines and `Marsh Seedless' grapefruits, stem end rot (Alternaria citri), as well as sour rot (Geotrichum candidum) of `Dancy' tangerines after irradiation.

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C. Stevens, V.A. Khan, J.Y. Lu, C.L. Wilson, P.L. Pusey, M.K. Kabwel, Y. Mafolo, J. Liul, E. Chalutz, and S. Droby

Applying low doses of ultraviolet light (254 nm, W-C) reduces the incidence of brown rot of (Monilinia fructicola) peaches, green mold (Penicillium digitatum) of tangerines, and Rhizopus soft rot (Rhizopus stolonifer) of tomatoes and sweetpotatoes resulting from field infection and artificial inoculation. In most studies, applying postharvest fungicide (PF) was better than W-C treatment. In this study, the effectiveness of combining a biocontrol agent, Debaryomyces hansenii (BC), with low UV-C dose for postharvest disease control was investigated. When these commodities were treated with BC 3 days after W-C treatment, the reduction of storage rots was more effective than when UV-C was used alone. For example, the percent brown rot infection of artificially inoculated Elberta peaches 36 hours after inoculation of the nontreated control, peaches treated with UV-C, BC, W-C + BC, and benlate were 100%, 55%, 67%, 12%, and 12%, respectively. The efficacy of W-C + BC was similar to when PF was used alone, indicating that an integration of UV-C treatment and BC can reduce storage rot to the levels of commercial PF treatment.

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A.L. Moyls, P.L. Sholberg, and A.P. Gaunce

A fumigation technique using brief exposure of fruit to a low concentration of acetic acid vapor was combined with modified-atmosphere packaging to reduce storage rots and increase shelf life of grapes (Vitis vinifera L.) and strawberries (Fragaria ×ananassa Duch.) by two or three times normal values. Both commodities were inoculated with spores of Botrytis cinerea Pers. before fumigation with acetic acid, packaging, and storage at lowered O2 levels. Fumigation with acetic acid at 8.0 mg·L–1 followed by modified-atmosphere packaging for 74 days at 0 °C reduced the percentage of rotted grapes from 94% to 2%. Strawberries fumigated with acetic acid at 5.4 mg·L–1 were free of decay compared to 89% rotted for the control fruit stored for 14 days at 5 °C.

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Ibrahim I. Tahir, Eva Johansson, and Marie E. Olsson

This 4-year study at the Kivik research station, southeastern Sweden (≈55°N), investigated optimal orchard management procedures to improve tree growth, yield, fruit quality, and storability in the important early season apple cultivar ‘Katja’. Two procedures (one standard, one novel) were applied within pruning, weed control, fertigation, and thinning, yielding a total of 16 different combinations (treatments). Tree vegetative growth, yield, fruit size, fruit color, firmness, soluble solids concentration, malic acid, nitrogen and calcium content, and percentage fruit with storage rot (Pezicula malicorticis) were evaluated for all 16 treatments. Changing to the novel alternative in only one or two of the areas did not produce significant improvements in all investigated parameters. The optimal treatment consisted of radical winter pruning + summer pruning (novel), bark mulching (novel), fertigation with 0.13 g N (standard), and hand thinning after full bloom (novel).

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C. Stevens, P. L. Pusey, V. A. Khan, J. Y. Lu, C. L. Wilson, E. Chalutz, M. K. Kabwe, Z. Haung, O. Adeyeye, and J. Lin

Low hormetic doses of ultraviolet light (UV-C) stress on exposed peaches (Prunus persica). reduced brown rot resulting from field and artificial inoculation from Monilinia fructicola. To test the hypothesis that UV-C induced resistance through host responses the following tests involving biochemical changes (phenlyalanine ammonia-lyase activity (PAL) and ethylene production (EP)), bioassay of antifungal activity of tissue extracts to the fungus, and latent infection of rot free peaches previously treated with and without UV-C were determined. Exposure of peaches to UV-C dose of 7.5×104 ergs/mm2 promoted an increase in PAL and EP compared to the control. As the PAL activity increased, percent storage rots decreased. Antifungal activity to the fungal conidia in UV-C treated peach extract showed that the percent conidia germination was reduced 3 folds. Preharvest infection of brown rot which indicated latent infection was significantly reduced. To test for the germicidal effect of UV-C on M. fructicola on the surface of peaches, an artificial epiphytic population of the fungus was deposited on the peaches. A negative relationship between UV-C dose of 1.3 to 40×104 ergs /mm2, colony forming units and number of decaying brown rot lesions were found.