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Vincent Russo

There is a question whether it is best to use synthetic or organic materials to fertilize horticultural crops. Fertilizer rate can effect nutritional value of banana squash (Curcubita maxima Duch.) which is used in processed food. Seed were planted in 1990, 1991 and 1992 into beds treated with recommended (base) and twice the recommended (2X) rates of synthetic or organic fertilizers. Lime was or was not first applied in spring 1991. Synthetic fertilizer produced better yields than organic fertilizer. In 1990, the base fertilizer rate improved yield. In 1992, the 2X fertilizer rate improved yield. Liming did not affect yield. Beginning soil pH was 5.55. For lime augmented treatments soil pH was increased to, and maintained at, 5.65 through fall 1992. For no-lime treatments soil pH was approximately 5.3 through fall 1992. Organic materials, likely bound to soil under acidic conditions, are less available and could explain lower yields. The data suggests that soil pH will have to be improved before banana squash yields can be increased using organic fertilizers.

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Jim Menzies, Pat Bowen, David Ehret, and Anthony D.M. Glass

The effect of soluble potassium silicate applied to cucumber (Cucumis sativus L.), muskmelon (C. melo L.), and zucchini squash (Cucurbita pepo L.) on the severity of powdery mildew was examined. Application methods included amending nutrient solutions to a concentration of 1.7 mm Si and foliar sprays containing 1.7, 8.5, 17, and 34 mm Si. Untreated plants and plants sprayed with distilled water were used as controls. The leaves of all plants were inoculated with known concentrations of conidia of Sphaerotheca fuliginea (Schlecht.:Fr.) Poll. (cucumber and mu&melon) or Erysiphe cichoracearum DC.: Merat (zucchini squash) 1 day after the sprays were applied. Inoculated leaves on plants receiving the Si-amended nutrient solution or foliar sprays of ≥ 17.0 mm Si developed fewer powdery mildew colonies than those on control plants. Results of a separate experiment that included a potassium spray, indicated that the active ingredient of the potassium silicate sprays appears to be Si. Experiments to test the persistence of Si foliar sprays on cucumber demonstrated that a 17 mm Si spray applied 7 days before inoculation with S. fuliginea reduced mildew colony formation.

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Erik B. G. Feibert and Clint C Shock

Eight winter squash varieties (Table Ace Acorn, Sweet Dumpling, Waltham Butternut, Honey Boat, Sugar Loaf, Spaghetti, Gold Keeper, and Kabocha) were placed in storage 3 weeks after harvested and were stored for 6, 12, or 16 weeks at 5, 10, or 15°C and 50, 60, or 70 percent relative humidity. Before storage Spaghetti squash had low dry weight and low sugars while Kabocha, Sugar Loaf, and Honey Boat had high dry weight and high sugars. Squash of all varieties suffered high spoilage when stored at 5°C. Water losses increased with temperature or with storage at 50 percent relative humidity. Considering both spoilage and water loss, marketable fruit was highest when squash was stored at 10°C or 15°C and 60 or 70 percent relative humidity. Squash sugars were maintained with storage at 5°C and 10%. Squash can be stored for several months at 10°C and 60 to 70 percent relative humidity with little fruit loss or loss of sugar.

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J. Brent Loy

Premature harvest of acorn squash is a widespread problem because fruits reach maximum size and optimum color within 20 days after pollination (DAP), well before peak dry matter and sugar content occur. The present study was conducted to determine the relationship between harvest date and physiological factors affecting eating quality in Cucurbita pepo L. squash. In the summer of 2005, C. pepo squash cultivars were evaluated at three harvest dates, 25, 35, and 45 days after pollination (DAP), with or without a 10-day storage period at 21 °C. Four F1 hybrid cultivars carrying powdery mildew tolerance (PMT) were evaluated: a semi-bush, commercial acorn cultivar (`Tip Top'), a high quality experimental acorn, bush hybrid (NH1634), and two sweet dumpling-type, semi-bush hybrids (NH1635 and 1636). Data were collected on mesocarp DW, oBrix (soluble solids), and partitioning of biomass between mesocarp tissue and developing embryos during storage. Peak DWs of 20% to 21% occurred at 25 DAP in NH1634, 1635 and 1636, and at 35 DAP in Tip Top (19.5 %). At 25 DAP, Brix was low (means of 5.9 to 7.2) across all cultivars. With harvest at 25 DAP plus 10 days storage, oBrix was low in Tip Top (7.1), but was higher than 10 in NH1634 and NH1636. Brix reached near maximum (13 to 15) at 45 DAP in NH1634, 1635 and 1636, and at 55 DAP in Tip Top (12). Embryos were small (DW = 8 to 19 mg) at 25 DAP and grew fairly linearly to a maximum at 55 DAP. Mean embryo DW at 55 DAP was 87.5 mg for Tip Top, 76.9 mg for NH1636, 57.1 mg for NH1634, and 28.5 mg for NH1635. The proportion of total fruit biomass expressed as energy equivalents (kJoules) allocated to embryos in mature fruit (45 DAP + 10 days storage) was 11.8% in NH1635, 18.7% in NH1634, 27.4% in Tip Top, and 30.2% in NH1636. Reallocation of assimilates from mesocarp tissue to developing embryos was a major contributing factor, along with respiration, to a reduction in mesocarp dry matter during storage.

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Mark E. Herrington, Svenning Prytz, Ross M. Wright, Ian O. Walker, Peter Brown, Denis M. Persley, and Ray S. Greber

1 E-mail address: herrinm@dpi.qld.gov.au 2 Retired. We acknowledge the financial support for the development of the resistant squashes: 'Dulong QHI' from HRDC (Horticultural Research and Development Corporation); AUSVEG and QFVG (Queensland

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Judy G. Schmalstig and Heather J. McAuslane

Squash silverleaf (SSL) is a physiological disorder of vegetables in the genus Cucurbita L. caused by feeding of nymphs of the silverleaf whitefly (SLW) (Bemisia argentifolii Bellows & Perring). SSL causes a silvering of the leaves and a blanching of fruit. Leaf silvering is caused by developmental separation of the upper epidermis and the palisade mesophyll layer resulting in additional air space and altered light reflection. The anatomical development of SSL was analyzed in young leaves of zucchini squash (Cucurbita pepo L.) using two susceptible genotypes (`Elite' and YSN347-PMR) and two tolerant genotypes (ZUC76-SLR and ZUC33-SLR/PMR). SLW nymphs were allowed to feed only on the mature leaves and the anatomy of the developing leaves was observed by light microscopy and transmission electron microscopy. Silvering began at the apex of young leaves and developed basipetally. The increased percentage of air space that resulted between the upper epidermis and palisade layers was the result of an increase in the duration of air space development in young, developing leaves. Chloroplasts in silvered tissue of mature leaves and in tissue of young leaves that later became silvered, were smaller and contained less starch than chloroplasts in tissue from noninfested plants. In contrast, development of genetic silvering, a condition not related to whitefly feeding, occurred throughout the entire leaf at one time, beginning as yellowed tissue in the axils of leaf veins then turning silver. Chloroplasts were normal in genetically silvered tissue of genotype YSN421-PMR. The SSL-tolerant genotype, ZUC76-SLR, did not show alteration in chloroplast structure or air space development when challenged with SLW; however, it had shorter and paler petioles, as did the susceptible genotypes. SSL symptoms were induced with spraying of gibberellic acid synthesis inhibitor chlormequat chloride in SSL-susceptible but not in SSL-tolerant genotypes. Reciprocal grafting between susceptible and tolerant plants showed that tolerance resides in the developing tissue and not the mature tissue on which the whiteflies feed.

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Michelle L. Infante-Casella and Steven A. Garrison

Many squash varieties are large-seeded and may be well-suited for planting under no-till production systems. A study was done at the Rutgers Agricultural Research and Extension Center in Bridgeton, N.J., to evaluate the yield and loss of soil when butternut squash (BS) (Cucurbita moschata `Waltham') was grown using no-till (NT), strip-till (ST), and bare ground (BG) tillage systems. The soil was a Sassafrass gravely sand loam and the field had a 3% slope. A cover crop mixture of hairy vetch and winter rye planted on 23 Sept. 1998 using a Brillion seeder at a rate of 136.2 kg/ha and 610.2 kg/ha, respectively, was used to create the NT and ST plots. NT and ST plots containing the cover crop mixture were killed with Glyphosate and chopped using a Buffalo stalk chopper on 27 May. BG plots were tilled clean before planting and ST plots were rototilled to a 30.48 cm band to establish a seedbed. BS seeds were hand-planted on 7 July with a spacing of 38.1 cm between plants and 182.9 cm between rows. Irrigation was applied overhead at a rate of 6.28 cm/ha weekly. Erosion was measured using inverted pans over the soil area to be measured. Harvest took place on 21Oct. and yields included only marketable fruit with the following results: NT = 8.65 t/ha; ST = 8.99 t/ha; BG = 4.06 t/ha. Yields in the NT and ST plots were significantly higher than yields in the BG plots. Soil erosion measurements were taken on 21 Oct. Soil loss results from the plots were 0.08 cm (NT), 0.84 cm (ST), and 3.33 cm (BG). Soil loss, mainly due to water erosion, was significantly higher in the BG plots. BS yields can be significantly higher when using alternative tillage systems like NT and ST. When using NT and ST systems for the production of BS, soil erosion is reduced

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Qi Zhang, Andy Medina, and Chuck Lyerly

Summer squash are generally regarded as any variety of Cucurbita used immature as a table vegetable, but more commonly refer to any cultivated type of Cucurbita pepo that produces immature fruit for consumption ( Herrington and Persley, 2002

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Hidemi Izumi and Alley E. Watada

Physiology and quality of CaCl2 treated or nontreated `Elite' zucchini squash slices were monitored during storage in air, low O2 (0.25, 0.5 and 1%) or high CO2 (3, 6, and 10%) atmosphere at 10C. O2 consumption and CO2 production were reduced under low O2 and high CO2 atmospheres and the reduction was greater with low O2. C2H4 production was reduced with low O2 and initially with high CO2. After day 2 or 4, C2H4 production under high CO2 increased with the increase being greater at the lower CO2 level. The amount and severity of injury/decay were less under low O2 and high CO2 than air atmosphere. Slices stored under 0.25% O2 atmosphere had less weight loss and injury/decay and greater shear force and ascorbic acid content than those held in air atmosphere. Microbial count, pH, and color were affected by the low O2 only on the last day. CaCl2 had no additive effect.

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

Winter squash is grown in the Northwest of Mexico for export to distant markets with risk of produce loss. A study was conducted to investigate its postharvest behavior as affected by hot water (50°C) for 0, 3. 6, 9 and 12 min, and stored at 10 or 20°C with 75% RH for 4, 8, and 12 weeks. The highest weight loss (11.35%) was in fruits without hot water treatment stored at 20°C for 12 weeks; at this temperature the weight loss was 3.65, 7.18, and 10.19% in the 4, 8 and 12 week storage period, respectively. At 10°C the weight loss was 3.41, 6.83 and 7.56% for the same period. Chlorophyll content decreased as temperature and storage period increased. β-carotene content showed no change at 10°C, but slightly increased after 8 and 12 weeks at 20°C. Fruits showed decay by Rhizopus and Aspergillus. Weight loss, chlorophyll content, and decay were not affected by length of hot water treatment. General appearance was better in fruits stored at 10°C than at 20°C.