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Todd C. Wehner, Nischit V. Shetty, and L. George Wilson

All available cucumber (Cucumis sativus L.) cultigens were tested for combining ability for fruit storage ability by crossing them with the gynoecious inbred Gy 14. Fruit weight and firmness were measured before and after storage, and fruits were rated for water loss after storage. The cultigens with the lowest percentage of fruit weight loss during storage were PI 172839, PI 344067, PI 264667, PI 171612, PI 339245, PI 220171, PI 279469, and PI 368550; those with the lowest percentage of loss in fruit firmness were PI 379284, PI 339241, PI 414159, PI 422177, `Regal', PI 109483, `Addis', PI 285603, PI 257486, and `Calypso'. The cultigens demonstrating the least fruit shriveling were `Dasher II', `Sprint 440', `Texas Long', PI 390255, PI 432870, `Pacer', PI 419078, PI 390247, PI 321011, and PI 414158. The 10 best cultigens from the initial screening study, along with the four worst cultigens and six checks, were retested directly (not as F1 progeny) for fruit keeping ability in two storage conditions and at two harvest dates. No significant differences were detected between the two harvest dates and storage conditions.

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Barrett C. Wilson, Jeff L. Sibley, and James E. Altland

A study evaluating the effects of varying levels of chilling on foliar budbreak of linden (Tilia spp.) culivars was initiated in 1999 in Auburn, Ala. [lat. 32°36'N, long. 85°29'W, elevation 709 ft (216m), USDA Hardiness Zone 8a]. Littleleaf linden (T. cordata) `Greenspire' and `Fairview' required the most chilling to produce measurable budbreak and exhibited the lowest budbreak percentages. Silver linden (T. tomentosa) `Sterling' and american linden (T. americana) `Redmond' needed the fewest hours of chilling to produce budbreak and exhibited the highest budbreak percentages. `Sterling' was the top performer in foliar budbreak percentage and in subsequent growth. Although `Redmond' attained high budbreak numbers, its overall growth during the following growing season was inferior to that of `Sterling', `Greenspire' and `Fairview'. This information can contribute to the development of regional planting recommendations, which can aid in the selection of lindens suitable for the area in which they will be grown. Calculated r2 values indicated the models used provided a good fit to the data for all cultivars.

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C L. Wilson, B. Upchurch, A. El Ghaouth, C. Stevens, V. Khan, S. Droby, and E. Chalutz

An apparatus was designed to deliver low-dose UV-C light to the surface of fruit on a processing line and tested for its control of postharvest decay. It consisted of a row of UV-C emitting lamps mounted on a frame above a conveyer belt that transported the fruit. The dosage of the UV-C light delivered to the fruit surface was regulated by varying the speed of the conveyor belt. Postharvest decay after 28 days storage of `Empire' apples was reduced 52% relative to the untreated checks when the fruit were conveyed at 6.2 m·min−1 (1.38 kJ·m−2 dose) under the UV-C apparatus. Factors affecting the practical application of UV-C irradiation of fruit for controlling postharvest decay are discussed.

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C. Stevens, L. P. Pusey, V.A. Khan, J.Y. Lu, C.L. Wilson, M.A. Wilson, M.K. Kabwe, J. Liu, E. Chaultz, and S. Droby

Flavorcrest, Camden. C. L. Wilson, Loring, Elberta, Summergold and Harken peach varieties were inoculated and naturally infected with Monilinia fructicolo after ultraviolet light irradiation (W-C 254nm) showed increased resistance to brown rot disease. Although dosages ranged from 0 to 20 KJ/m2. 7.5 KJ/m2 was considered the most effective for the peach varieties tested. Pretreatment of peaches by field spraying or dipping into a benomyl fungicide showed no significant differences between non-treated and UV-C treated peaches. However. a combination of a low dose of benomyl (.15g/L) 3 days following UV-C treatment showed a synergistic effect on brown rot reduction when compared to Peaches treated with UV-C alone and a greater reduction of brow rot than benomyl control.

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

Jewel sweetpotato storage roots previously treated with ultraviolet (UV–C) light and then stored for 30 days before artificial inoculation with Fusarium solani showed increased resistance to Fusarium root rot; as indicated by reduced lesion size, the rate of decay development of rotted tissues. There was a hormetic relationship between the incidence of Fusarium root rot and UV–C doses. The optimum dose of UV which reduced Fusarium root rot was 3.6× 104 ergs/mm2. Exposure of sweetpotato to UV–C doses promoted phenylalanine ammonia–lyase (PAL)4 production with the maximum PAL activity occurring at 3.6×104 ergs/mm2. Crude extracts from UV–C treated sweetpotatoes reduced germination, germ tube elongation and growth of F. solani when compared to untreated extracts.

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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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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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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.

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L. Ferguson, J.A. Poss, S.R. Grattan, C.M. Grieve, D. Wang, C. Wilson, T.J. Donovan, and C.-T. Chao

Performance of `Kerman' pistachio (Pistacia vera L.) trees on three rootstocks (P. atlantica Desf., P. integerrima Stewart and `UCB-1', a P. atlantica × P. integerrima hybrid) was evaluated with 2-year-old trees grown in sand-tank lysimeters under combined SO4 2- and Cl- salinity and boron (B) stress for 6 months. Four salinity treatments were imposed by irrigating the plants with water at electrical conductivity (ECiw) of 3.5, 8.7,12, or 16 dS·m-1 each containing B at 10 mg·L-1. Growth of `Kerman' was evaluated based on increase in total leaf area, increase in trunk diameter, and total above-ground biomass production. All growth parameters decreased as salinity increased, but were not significant until ECiw exceeded 12 dS·m-1. However, growth of `Kerman' on P. atlantica and `UCB-1' was considerably better than on P. integerrima at 16 dS·m-1. The onset and severity of foliar injury differed among scions and treatments and was attributed primarily to B toxicity, rather than the effects of salinity. Concentrations of B in injured leaf tissue ranged from 1000 to 2500 mg·kg-1. Leaf injury decreased with increasing salinity, although leaf B was not significantly reduced suggesting an internal synergistic interaction between B and other mineral nutrients. However for P. vera on P. integerrima, the highest level of salinity produced the greatest injury, possibly as a combination of B plus Cl- and/or Na+ toxicity. Leaf transpiration, stomatal conductance, and chlorophyll concentration of P. vera, determined by steady-state porometry, were also reduced to a greater degree by combined salinity and B when budded on P. integerrima than on the other two rootstocks.