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David J. Schuster, James B. Kring and James F. Price

The sweetpotato whitefly, Bemisia tabaci (Gennadius), was associated with symptoms of a silverleaf disorder of acorn squash (Cucurbita pepo L. cvs. Table King Bush and Table Ace) in cage studies in the greenhouse. Symptoms appeared on uninfested leaves that developed after plants were infested with the whitefly. When the infested lower leaves were removed and the young leaves protected from infestation with insecticides, new growth was asymptomatic or nearly so and symptomatic leaves remained symptomatic. Symptom expression was related more to nymphal density than to adult density since the relationship between log nymph density and symptoms was linear when adult densities were equal.

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J. George Buta and Chien Y. Wang

Fourier transform infrared (FTIR) spectroscopy detected early large increases in fluid leakage from zucchini squash (Cucurbita pepo L.) subjected to a chilling temperature (5C). The increase in fluid leakage (principally water) was found after 1 day at 5C, while surface pitting was detected only after 3 days of storage at 5C. Prestorage temperature conditioning at 15C for 2 days greatly diminished the fluid leakage measured by FTIR spectroscopy after 1 day of storage at 5C. Measuring fluid leakage using FTIR spectroscopy seems to be a promising technique to detect the early onset of chilling injury.

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Chien Yi Wang

Temperature conditioning of zucchini squash (Cucurbita pepo L.) at 15°C for 2 days enhanced polyamine levels and delayed the development of chilling injury during storage at 5°C. Direct treatment of zucchini squash with polyamines increased the endogenous levels of polyamines and reduced chilling injury. However, treatment with polyamine inhibitors after harvest but before temperature conditioning suppressed the increase of endogenous polyamines and reduced the benefit obtained from temperature conditioning. These results suggest that the resistance of squash to chilling injury may be related to the endogenous levels of polyamines.

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Alyssa H. Cho, Alan W. Hodges and Carlene A. Chase

Partial budget analyses of five summer fallow treatments in Florida preceding a cash crop of summer squash (Cucurbita pepo) were conducted. The five treatments were sunn hemp (Crotalaria juncea), velvet bean (Mucuna deeringiana), cowpea (Vigna unguiculata), sorghum-sudangrass (Sorghum bicolor × S. bicolor var. sudanense), and tillage. Costs were estimated for each summer fallow treatment, including the cost of seed, inoculant, implementation, management, and termination. Benefits were calculated in terms of contributions to the following cash crop of summer squash in the form of biologically fixed nitrogen and reduced weed pressure. Results showed that total production costs were minimized by cover crops, even though implementation costs were higher than for tillage.

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J.E. Brown, R.P Yates, C. Stevens and V.A. Khan

Effects of planting methods and rowcover on the production of yellow crookneck squash, Cucurbita pepo L. var. melopepo Alef., were evaluated over 2 years at the E.V. Smith Research Center, Shorter, Ala. Summer squash was direct-seeded or transplanted in the field with or without black plastic mulch and grown with or without rowcover. Yield of transplanted squash was significantly increased over the same squash direct-seeded. Neither plastic mulch nor rowcover had an effect on summer squash production. Transplants matured 8 to 10 days earlier than the direct-seeded plants.

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R. Provvidenti and David M. Tricoli

In a yellow summer squash (Cucurbita pepo L.) experimental line developed by Seminis Vegetable Seeds, the coat protein gene of an American strain of squash mosaic virus (SqMV-M88), conferred resistance to Arizona, California, New Jersey, and New York strains belonging to the two pathotypes of the virus. An analysis of genetic populations derived from crosses and reciprocal backcrosses of a homozygous SqMV-resistant line A127-1-2 with the susceptible cultivar Butterbar revealed that the high level of resistance mimics the response of a single recessive gene.

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Richard G. Snyder, Frank Killebrew and Joseph A. Fox

Yellow squash (Cucurbita pepo L.) planted after early spring in Mississippi have a strong likelihood of developing green streaks and blotches on the fruit-symptoms of watermelon mosaic virus strain 2. Cultivars with the relatively new precocious yellow gene (PYG) tend to show such symptoms less prominently, and in some cases not at all, when infected. Field trials were conducted at two locations to evaluate several PYG cultivars and compare their WMV-2 symptoms to those of standard, non-PYG types. In both cases, the PYG cultivars had fewer unmarketable fruit due to WMV-2 symptoms, although they were not entirely immune to the virus.

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Chien Yi Wang

Methyl jasmonate (MJ) was applied to zucchini squash (Cucurbita pepo L.) fruit be pressure-infiltration (82.7 kPa for 3 min). Control fruit were similarly treated with distilled water. All fruit were then stored at a chilling temperature of 5C. Chilling injury occurred in the control fruit within 4 days of storage. However, the onset of chilling injury was significantly delayed by the MJ treatment. MJ-treated fruit also maintained higher levels of carbohydrates, while malic acid was the major organic acid. These constituents deteriorated slower in the MJ-treated fruit than in the control fruit.

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S. Alan Walters and Bradley H. Taylor

The objective of this study was to measure honey bee (Apis mellifera L.) impact on seed set, fruit set, and yield of jack-o-lantern (Cucurbita pepo L.), large-sized (C. maxima Duch.), and processing pumpkins (C. moschata Duch. ex Poir.) under field conditions. There were sufficient natural pollinators [including bumblebees (Bombus spp.), carpenter bees (Xylocopa spp.), honey bees, and squash bees (Peponapis pruinosa Say)] provided under field conditions to induce fruit set of jack-o-lantern pumpkins as fruit number obtained per hectare was not affected by the addition of a honey bee colony. However, the addition of honey bees did increase fruit number per hectare of the C. moschata and C. maxima cultivars evaluated. Honey bee pollination resulted in larger-sized fruit, increasing individual fruit size of all but small-sized pumpkins (<0.5 kg). Individual pumpkin fruit weights of the Cucurbita pepo, C. moschata, and C. maxima cultivars evaluated increased by about, 26%, 70%, and 78%, respectively, when honey bee colonies were included. Natural pollination was insufficient to stimulate maximum fruit size development and seed number and seed weight per fruit. Although pumpkin fruit set will occur with natural pollinators, the addition of honey bee colonies will ensure the presence of pollinators to maximize fruit size. Since pumpkins are generally sold on a weight basis, growers may generate greater revenues with the addition of honey bee colonies in pumpkin fields.

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Vladimir Meglic, Jack E. Staub and Larry D. Knerr

Thirty-eight cultivated accessions of the diverse Cucurbitaceae were electrophoretically surveyed using 13 enzyme systems. Included were representatives from 6 of the 6 Cucurbitaceae tribes, 9 genera, and 17 species. Additionally, several cultivars or groups were included for those species possessing marked morphological diversity such as the 7 groups of Cucumis melo var. melo and 7 of the numerous cultivars representing Cucurbita pepo. Zymograms were scored for the presence or absence of bands measured in mm from the origin. Cluster analysis (complete linkage method) was used to detect affinities among the accession surveyed. Data suggest that: 1) Cucumis melo (x=12) possessed greater biochemical affinity with C. sativus (x=7) than with either C. anguira or C. metuliferus (both x=12); 2) Sechium edule and Cyclanthera pedata. both members of the tribe Sicyeae, were more closely associated with members of other tribes than with each other; 3) Some cultivars of Cucurbita pepo shared greater affinity with Cucurbita moschata than with other cultivars of C. pepo. Additional observations as well as their possible implications will be presented.