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María Ferriol, Belén Picó, and Fernando Nuez

Cucurbita maxima Duch. is one of the most morphologically variable cultivated species. The Center for Conservation and Breeding of the Agricultural Diversity (COMAV) holds a diverse germplasm collection of the Cucurbita genus, with more than 300 landraces of this species. Morphological and molecular characterization are needed to facilitate farmer and breeder use of this collection. With this aim, the morphological variation of a collection of 120 C. maxima accessions was evaluated. The majority of these accessions originated from Spain, which has acted as a bridge since the 16th century for spreading squash morphotypes between the Americas and Europe. South American landraces (the center of origin of this species) were also included. Eight morphological types were established based on this characterization and previous intraspecific classifications. A subset of these accessions, selected from these classification and passport data, was employed for molecular characterization. Two marker types were used; sequence related amplified polymorphism (SRAP), which preferentially amplifies open reading frames (ORF), and amplified fragment length polymorphism (AFLP). In the main, SRAP marker analysis grouped accessions in accordance to their type of use (agronomic traits) and AFLP marker analysis grouped accessions as to their geographical origin. AFLP marker analysis detected a greater genetic variability among American than among Spanish accessions. This is likely due to a genetic bottleneck that may have occurred during the introduction of squash into Europe. The disparity of the results obtained with the two markers may be related to the different genome coverage which is characteristic of each particular marker type and/or to its efficiency in sampling variation in a population.

Open access

Adel M. El-Sheikh, A. Ulrich, S. K. Awad, and A. E. Mawardy

Abstract

Squash (Cucurbita pepo), cucumber (Cucumis sativus), muskmelon (Cucumis melo) and corn (Zea mays.) plants were grown in sand culture with B as the variable. The plants were harvested when they showed a definite gradation of B toxicity symptoms from severe to none. Mature blades were analyzed for total B.

A significant decrease in top growth took place in corn and cucumber for culture solutions with B concentrations greater than 2 ppm; in squash and muskmelon, greater than 4 ppm. A 50% decrease in top growth took place in solutions with 6, 12, 12 and 16 ppm of B for cucumber, squash, muskmelon and corn, respectively, with cucumber the most sensitive and corn the least sensitive to B supply. The critical concentrations for B toxicity in mature blades at the onset of decreased top growth are 100, 400, 800 and 1,000 ppm, dry basis, for corn, cucumber, muskmelon and squash, respectively.

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Charles S. Krasnow, Rachel P. Naegele, and Mary K. Hausbeck

The oomycete plant pathogen Phytophthora capsici Leonian affects the cucurbit industry annually, in some cases causing 90% to 100% crop loss ( Babadoost, 2000 ; Meyer and Hausbeck, 2012 ). Michigan is a leading producer of processing squash

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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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Elizabeth A. Wahle and John B. Masiunas

Two experiments were conducted to evaluate processing pumpkin and processing squash tolerance to preemergence herbicides. The experiments were randomized complete block designs with three or four replications. The herbicides were applied after seeding the crop using a CO2-pressurized sprayer delivering 233 L/ha. We evaluated clomazone alone, and in combination with either halosulfuron or sulfentrazone. The first experiment was conducted in Morton, Ill., using `Libby's Select' processing pumpkin (Cucurbita moschata). None of the treatments caused any significant pumpkin phytotoxicity. On 7 July all treatments reduced the number of grass weeds compared to the untreated control. There were no differences in grass control between the herbicide treatments. Broadleaf control was best in sulfentrazone at 0.56 kg/ha or clomazone + halosulfuron at 0.56 + 0.13 kg/ha and worst in the untreated control. Weed control decreased by the 29 July rating; grass and broadleaf weed control was unacceptable in all treatments due to infestation with perennial weeds. Sulfentrazone alone or with clomazone was safe for use on pumpkins in heavier soils. The second experiment, conducted in Champaign, Ill., used `NK530' processing squash (Cucurbita maxima). None of the treatments caused any squash phytotoxicity. The best control on 14 July was with combinations of clomazone and sulfentrazone. On 10 Aug., all herbicide treatments were similar in their control of broadleaf weeds. Sulfentrazone and halosulfuron do not injure processing pumpkin or squash when applied either alone or in combination with clomazone.

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Harry S. Paris, Peter J. Stoffella, and Charles A. Powell

Summer squash (Cucurbita pepo L.) plants were grown in pots with high (290% capacity) or low (45% to 70% of capacity) soil moisture. The plants were exposed or not exposed to sweetpotato whiteflies (Bemisia tabaci Genn.). Only the plants exposed to whiteflies developed leaf silvering. Silvering was more severe in plants subjected to low soil moisture.

Open access

Fabio Mencarelli

Abstract

Zucchini squash (Cucurbita pepo L. cv. Romanesco) were stored 19 days at 5°C in 21% ± 1% O2 plus 0.0%, 2.5%, 5.0%, or 10.0% CO2 and then stored an additional 4 days at 13° in air. High CO2 levels inhibited the rate of CO2 production and reduced the development of chilling injury symptoms at all three maturities (16, 20, and 22 cm fruit). There was a high negative correlation between CO2 levels and reduction of chilling injury. At the end of the 23-day storage period, 82% of the 22-cm squash held in 10% CO2 appeared salable, but they had a slight off-flavor and were soft; 79% of the fruit held in 5% CO2 were salable, firm, and free of off-flavors; samples from 2.5% CO2 and air were unacceptable because of decay and pitting. The percentage of unsalable fruit increased from 16- to 20-cm squash. Carbon dioxide concentrations around 5% may be useful for storing zucchini squash at about 5°, a temperature that normally causes chilling injury in zucchini.

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Michelle L. Infante-Casella and Mel Henninger

Zucchini and straightneck yellow squash are important crops for vegetable farmers. Variety choices change from year to year, based on breeding programs that try to find disease tolerance or resistance by developing new lines. A study was conducted at the Rutgers Agricultural Research and Extension Center in Bridgeton, N.J., to determine yield and quality of 14 zucchini, 6 yellow squash, and 5 specialty squash varieties. Squash were seeded on 17 May 2004, at 30 inches between holes into black plastic mulch on high raised beds. Rows were spaced 60 inches apart. Drip irrigation was used for supplying water and fertigation. Prefar4E at a rate of 5 qt/acre applied on the soil surface just before laying plastic was used for preemergent weed control. Five days after planting, Sandea75WF at a rate of 1 oz/acre and Gramoxone Max 3SC at a rate of 1.5 pt/acre were applied with a backpack sprayer between the rows for added weed control. Admire was applied in the seed hole at a rate of 24 oz/acre after planting using a backpack sprayer for control of aphids and cucumber beetle. Harvests began on 22 June 2004, and were continued 3 times weekly for 5 weeks for a total of 15 harvests. Zucchini varieties `Revenue', `Cashflow', `Justice III', `Spineless Beauty', `Senator', `HMX-2724', and `EXT 04629728' had statistically higher yields than did `Radiant', `Wildcat', `Payroll', `HMX-2723', `Lynx', `Tigress', and `Independence II'. Varieties are listed in values from highest yielding to lowest yielding, respectively. All yellow squash varieties had statistically similar yield values. These included `General Patton', `Cougar', `Sunray', `XPT1832', `Goldbar', `Sunbar'. Specialty varieties evaluated included `Zephyr', `Starship', `Magda', `Flying Saucer', and `Costata Romanesco'

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James E. Ells, Ann E. McSay, and E.G. Kruse

Irrigation scheduling programs were developed for cabbage and zucchini squash that produced high yield and water-use efficiency with a minimum number of irrigations. The irrigation programs are based on a soil water balance model developed by the USDA. The procedure involved selecting irrigation programs developed for similar crops and using them as standards for cabbage and zucchini for three growing seasons. The treatments involved irrigation levels higher and lower than the standard. After the third year, the best treatment for each year was selected. Coefficients for the standard model then were adjusted by trial and error to produce a program that called for the same number of irrigations and the same amount of water as the best-performing treatment when using the same weather data. These revised programs for cabbage and zucchini squash are available on computer disks and may be used on any IBM compatible PC provided wind, temperature, solar radiation, humidity, and precipitation data are available,

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D.S. NeSmith

Greenhouse and field experiments were conducted to determine the influence of transplant age on growth and yield of `Dixie' and `Senator' summer squash (Cucurbita pepo L.). Dry weight and leaf area measurements indicated that 28- to 35-day-old greenhouse-grown transplants grew more slowly after transplanting than plants that were 10, 14, or 21 days old. Older transplants flowered earlier; however, earlier flowering did not result in higher early yields. Transplants of varying ages did not differ greatly in yield and yield components in the field, although all transplants had higher early yields than the directly seeded controls. Results from these experiments suggest that 21 days may be a reasonable target age for transplanting summer squash. If transplanting were delayed by adverse planting conditions, 21-day-old transplants would likely have at least a 10-day window of flexibility before yields would be reduced notably by additional aging.