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Open access

W. C. Adlerz, G. W. Elmstrom, and D. E. Purcifull

Abstract

In a replicated field test in 1982 where natural virus incidence was 25% watermelon mosaic virus 1 (WMV-1) and 75% WMV-2, we observed mosaic symptoms at harvest in leaves and fruit of the yellow-fruited Cucurbita pepo L. ‘Butterbar’, ‘Early Prolific Straightneck’, and ‘Multipik’. The range in percentage of diseased plants among the cultivars was small (26–33%), but total diseased fruit exceeded 40% in ‘Butterbar’ and ‘Early Prolific Straightneck’ and was less than 10% in ‘Multipik’. In a replicated field test in 1983, ‘Early Prolific Straightneck’ and ‘Multipik’ squash plants mechanically inoculated at early flowering with WMV-1, WMV-2, and zucchini yellow mosaic virus (ZYMV) became 97–100% foliar diseased. Production of diseased fruit was significantly greater in virus inoculated ‘Early Prolific Straightneck’ plants (all 3 viruses) than in uninoculated plants, and significantly greater in ‘Multipik’ plants inoculated with ZYMV or WMV-1 than in those inoculated with WMV-2 or not inoculated. In both tests, there were significant delays in the development of fruit symptoms in virus infected ‘Multipik’ when virus infection was mainly WMV-2. The evidence suggests fruit symptoms were caused by viruses other than WMV-2, and that WMV-2 does not induce symptoms in fruit of ‘Multipik’.

Free access

Jake Uretsky and J. Brent Loy

In recent decades, F 1 hybrids in the genus Cucurbita have increasingly gained prominence over open-pollinated varieties, particularly in summer squash, ornamental pumpkin and acorn cultivars of C. pepo L. and kabocha cultivars of C. maxima

Free access

Jorge Pérez-Arocho and Linda Wessel-Beaver

Melonworm (Diaphania hyalinata) is one of the most damaging pests of squash and pumpkin (Cucurbita sp.) in tropical/subtropical regions of the Americas. In order to identify sources of resistence to melonworm, we evaluated 345 accessions of C. moschata, including both tropical and temperate types, originating from the Americas, Europe, Asia, and Africa. C. argyrosperma (65 accessions) was also evaluated. Accessions were field tested in five single-plant complete blocks planted over a 9-month period in Isabela, P.R. Each plant was evaluated for foliar damage (0–4 scale) at 3 and 6 weeks. Larval counts were made on a five-leaf sample at 8 weeks. Accessions were classified for degree of leaf mottling and pubescence. Differences among accessions were found for foliar damage and number of larva, but ranking of accessions varied, depending on the criteria used to measure resistance. In order to establish independent culling levels, we considered the lower 30% of accessions for each trait. The upper limit was ≤0.42 for foliar damage at 3 weeks, ≤0.50 damage at 6 weeks, and ≤1.25larva/plant. This led to the selection of 34 resistant accessions. We used a similar technique to identify the most susceptible accessions. The susceptible accessions will be used as a control group when the 34 selections are further evaluated. Within C. moschata, accessions with either green leaves or less pubescence had less leaf damage and fewer larva than accessions with mottled leaves or more pubescence. As a group, C. argryosperma accessions were more susceptible, and nearly all had mottled leaves and little pubescence. Untested accessions with green leaves and/or little pubescence might yield additional sources of resistance to melonworm.

Free access

Chien Yi Wang

The endogenous levels of abscisic acid (ABA) in zucchini squash were increased by temperature conditioning at 10°C for 2 days. This temperature conditioning treatment reduced the severity of chilling injury in the squash during subsequent storage at 2.5°C. The ABA levels remained higher in treated squash than in untreated samples throughout storage. Direct treatments of squash with ABA at 0.5 mM and 1 mM before storage at 2.5°C increased ABA levels in the tissue and were also effective in reducing chilling injury. The involvement of ABA in reducing chilling injury will be discussed.

Free access

Michael P. Hoffmann, Richard W. Robinson, Margaret M. Kyle, and Jonathan J. Kirkwyland

Seventy-six Cucurbita pepo L. cultivars and breeding lines were evaluated under field conditions for infestation levels and defoliation (leaf area consumed by beetles) by adult diabroticite beetles in 1992 and 1994. Striped and spotted cucumber beetles, Acalymma vittatum (F.) and Diabrotica undecimpunctata howardi Barber, respectively, were most common, but some western and northern corn rootworms, D. virgifera virgifera LeConte and D. barberi Smith and Lawrence, respectively, also were present. In general, pumpkin, delicata, acorn winter squash, scallop, and yellow straightneck summer squash types were the least infested and defoliated. Caserta/yellow, zucchini, caserta/zucchini, caserta, and precocious yellow straightneck types were the most infested and defoliated. The number of beetles per plant was correlated (r ≥ 0.72) with leaf defoliation and proportion of plants infested, indicating that beetle infestation is a good predictor of damage. The cultivars and breeding lines that were the least infested and defoliated can be used in breeding programs to develop desirable genotypes with reduced beetle preference. Conversely, those genotypes that were highly preferred have potential as trap crops for these beetle pests.

Open access

Sarah J. W. Loy, L. C. Peirce, G. O. Estes, and O. S. Wells

Abstract

Strip tillage was evaluated over a 2-year period as a cropping system for sites unsuitable for conventional tillage. Yields in clean cultivation and in 0.5- and 1.1-m strips tilled in established grass or grass/clover sod were compared in 1982 for sweet pepper (Capsicum annuum L.) and winter squash (Cucurbita maxima L.). Both interspecific and intraspecific competition were determined in 1983 for pepper. Squash yield was improved by a grass/legume sod, but pepper yield was unaffected. Both crops suffered severe competition in 1982 when grown in 0.5-m-wide strips, but yields per hectare in strips 1.1m wide equaled that in clean cultivation. In 1983, however, number of marketable fruit per hectare of marketable yield of pepper in 1.1-m strips was less than that in clean cultivated plots, although total number of harvested fruit did not differ. Both marketable and total pepper yields per hectare were significantly higher in clean cultivation in 1983 than in strips. Increasing the population density of pepper in the strip increased number of fruit harvested and total weight per hectare, and there was a significant benefit in using double rows. Competition in strips accompanying increasing population density seemed to be associated with increased water deficits.

Free access

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.

Open access

E. C. Baker and G. A. Bradley

Abstract

(2-Chloroethyl)phosphonic acid (ethephon) applied at 2- to 4-leaf stages on winter squash cultivars ‘Boston Marrow’, ‘Golden Delicious’ and ‘Hybrid 530’ resulted in pistillate flowers at most early nodes, but these generally aborted. Ethephon applications usually resulted in greater numbers of marketable squash which tended to be smaller in size. The only instance of a significant yield increase occurred on ‘Golden Delicious’ with 2 applications of 150 ppm ethephon. Earlier appearing nodes on ethephon treated plants produced marketable fruit and harvest, based on external color, could have been made up to a week earlier. Presently, ethephon seems to be of limited commercial promise for winter squash under Arkansas conditions.

Free access

G.H. Clough, S.J. Locascio, and S.M. Olson

Broccoli (Brassica oleracea L. var. italica), followed by tomato (Lycopersicon esculentum Mill) or squash (Cucurbita pepo L. var. melopepo), and then broccoli were produced in succession re-using the same polyethylene-mulched beds at two locations with different soil types. First-crop broccoli yield was earlier and greater with drip than with overhead irrigation and increased as N-K rate increased from 135-202 to 270-404 kg·ha-1. On a tine sandy soil, yields of second and third crops produced with residual or concurrent fertilization increased with an increase in N-K rate. On a loamy fine sandy soil, yields also increased as the rate of residual N-K increased; yields of second and third crops did not respond to rate of concurrently applied N-K, but were higher with concurrent than with residual fertilization, except total tomato yields were similar with either application time. With drip irrigation and concurrent weekly fertigation, yields equalled or exceeded those obtained with preplant fertilization and overhead irrigation.

Open access

Martha A. Mutschler and Oscar H. Pearson

Abstract

One of the most popular types of winter squash is the butternut squash, a member of the species Curcurbita moschata Duchesne. Butternut squash has a buff-colored exterior and deep orange-colored flesh. Although winter squash of this species were cultivated before colonial times, the typical butternut fruit shape is a recent innovation. Crookneck (CR) types were widely used in the temperate United States until the origin in the early 1930s of the shortnecked butternut (BN) fruit type from a crookneck cultivar. The unstable nature of the butternut trait was soon noted, but could not be explained. The purpose of this paper is to summarize published and unpublished information concerning the origin, characteristics, and genetic behavior of the buttemut/crookneck fruit trait.