consistently tested negative for PRSV and ZYMV even up to 98 DPI in 2017 when plants were near full maturity. Table 1. Trial 1 (2016): mean enzyme-linked immunosorbent assay (ELISA) readings of six Cucurbita moschata genotypes mock-inoculated (control) and
Wilfredo Seda-Martínez, Linda Wessel-Beaver, Angela Linares-Ramírez, and Jose Carlos V. Rodrigues
Kristen R. Hladun and Lynn S. Adler
Perimeter trap cropping (PTC) uses an attractive crop to concentrate pests at borders and reduce pesticide use while maintaining yield. A possible disadvantage of PTC could be pollen flow between border and main crops that are not interfertile. The effects of pollen composition and amount on seed and fruit production were investigated between a main crop species, butternut squash (Cucurbita moschata Duch. ex Poir), and a PTC species, blue hubbard (C. maxima Duch.). Butternut squash plants were hand pollinated in the greenhouse with three pollen composition treatments crossed with four pollen amounts. Pure butternut squash pollen and mixed pollen produced more seeds per fruit and heavier seeds than pure blue hubbard pollen, revealing some incompatibility between butternut and blue hubbard. Saturating pollen amounts produced up to six times more seeds than lower pollen amounts. Pollen composition did not influence fruit set or fruit weight, which are of central importance for crop yield. This study suggests that pollen flow between blue hubbard borders and butternut squash should not interfere with crop production as long as sufficient conspecific pollen is deposited on stigmas.
John M. Swiader and William H. Shoemaker
Field experiments were conducted over a 5-year period (1994-98) to determine the effect of various cropping systems (rotations) on fertilizer N requirements in processing pumpkins [Cucurbita moschata (Duchesne ex Lam.) Duchesne ex Poir.] on medium- to fine-textured soil. Treatments consisted of a factorial combination of five N fertilization rates (0, 56, 112, 168, 224 kg·ha-1 N) and four pumpkin cropping systems: 1) pumpkins following corn (Zea mays L.); 2) pumpkins following soybeans [Glycine max (L.) Merrill]; 3) pumpkins following 2-years corn; and 4) pumpkins following fallow ground. Cropping systems were chronologically and spatially arranged in two complete cycles, with pumpkin studies taking place in 1996 and 1998. Averaged over the two studies, the optimal N fertilization rate for highest total weight of ripe fruit following soybeans was estimated at 109 kg·ha-1 N, compared to 128 kg·ha-1 N following fallow ground, even though yields were similar, suggesting a soybean N-credit of 19 kg·ha-1 N. Concurrently, the N fertilizer rate for highest total ripe fruit weight following corn was estimated at 151 kg·ha-1 N, and 178 kg·ha-1 following 2-years corn, indicating a negative rotation effect on pumpkin N requirements of 23 and 50 kg·ha-1 N, respectively. Minimum N fertilizer requirements, the N fertilizer rate associated with a ripe fruit yield of 50 t·ha-1, were calculated at 45, 37, 69, and 47 kg·ha-1 N in the respective cropping systems. Negative effects from excessive N fertilization were greater in pumpkins following soybeans than in pumpkins following corn or 2-years corn, with reductions in total ripe fruit weight of 21%, 9%, and 3%, respectively, at the highest N rate. A critical level for preplant soil NO 3-N of 17.6 mg·kg-1 was identified above which there was little or no pumpkin yield response to N fertilization.
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
Dario J. Chavez, Eileen A. Kabelka, and José X. Chaparro
, squash, and gourd production was ≈20 million tons with China as the major producer followed by India, Russia, and the United States. Cucurbita moschata is a highly diverse winter squash species adapted to hot and humid weather and low altitudes. Fruit
Donald N. Maynard, Gary W. Elmstrom, and Linda Wessel-Beaver
Hybrids from crosses between bush/short-vined breeding lines and traditional, vining cultigens were evaluated in the fall 1993 season. Yields of individual hybrids were 0.51 to 1.73 times those of their vining parents and 0.83 to 4.41 times those of the bush/short-vined parents. The average yield response of 58 hybrids was 1.05 times that of vining parents and 2.15 that of bush/short-vined parents. Average fruit weight, flesh thickness, and flesh color of the hybrids tended to be intermediate between that of the bush/short-vined and vining parents. Plant habit of all hybrids was similar to that of the bush/short-vined parent early in the growth cycle, but some became viney later in the growth cycle. Fruit matured earlier on bush/short-vined parent and hybrid plants than on viney parent plants.
Linda Wessel Beaver and Ruth Cienfuegos
In order to effectively use recurrent selection for developing polygenic resistance to powdery mildew (Erysiphe cichoracearum), methods to quantify resistance need to be developed. Our objective was to compare several inoculation methods for their effectiveness in a half-sib selection breeding program. Seven inoculation methods and 3 controls were applied to each of two susceptible C. moschata varieties planted in pots and arranged in a randomized complete block design with five replications. The experiment was repeated two times. Single degree of freedom comparisons found no difference in number of lesions resulting from inoculation by rubbing host with infected tissue vs. attaching infected tissue. Using no adherent resulted in as many lesions as using triton. Egg white as an adherent resulted in fewer lesions than using triton or no adherent. Spraying with a triton spore suspension was not an effective method. While rubbing leaves is fast and easy, attaching pieces of infected tissue may afford more control of spore concentration.
Donald N. Maynard
Traditional varieties and selections of tropical pumpkins have long trailing vines that produce two to five fruit weighing from 2 to 20 kg each. Bush inbreds have been developed from crosses between `La Primera', `La Segunda', and `Seminole' with `Bush Butternut'. These inbred plants produce four to 10 early-maturing fruit weighing 1 to 2 kg each at the crown of the plant. Hybrids made with the vining types produce plants that have short or intermediate-length vines. Fruit are produced at the crown and on short laterals on the short-vine hybrids and on laterals on the intermediate-vine hybrids. Some short-vined and intermediate-vined hybrids produce higher yields than the traditional type, but fruit size is smaller and the fruit wall is generally thinner. C42-1-9-1 x Linea C. Pinta, an intermediate-vine type, produced the highest yield in spring (66.5 t·ha–1) and fall (39.9 t·ha–1) at Bradenton, Fla. About three fruit weighing 4 to 5 kg each were produced per plant.
Rebecca Nelson Brown and James R. Myers
Marker-based selection for resistance to zucchini yellow mosaic virus in squash (Cucurbita spp.) would allow breeders to screen individual plants for resistance to multiple viruses. The C. moschata landrace Nigerian Local is widely used as a source of resistance in C. pepo breeding programs. We used RAPDs and bulk-segregant analysis to screen two BC1 populations for a marker linked to the dominant major gene for resistance from Nigerian Local. The initial cross was Waltham Butternut × Nigerian Local; the test populations were created from reciprocal backcrosses to Waltham Butternut. Both populations segregated 1:1 for resistance when hand-inoculated with ZYMV. RAPD primers were screened on a resistant bulk and a susceptible bulk from each population, and Waltham Butternut and Nigerian Local. Primers that gave bands linked to resistance were further screened using DNA from individual plants in each population. The potential markers will be tested on several populations derived from crosses between summer squash (C. pepo) and Nigerian Local to determine if they would be useful for selection in a C. pepo background.
P. N. Maynard, G. W. Elmstrom, L. Wessel-Beaver, and T. G. McCollum
Calabaza is a pumpkin-like fruit that is grown throughout the tropics and subtropics. In the Caribbean “calabaza” is used in soups and other traditional dishes. In Puerto Rico, the 1987-88 calabaza crop was worth $8 million and the value of the crop in Florida is estimated to exceed $5 million. Mainland production of tropical calabaza types of C. moschata is limited largely to Florida where it is used mostly by those of Cuban descent. Despite the popularity and commercial significance of calabaza, little effort has been directed toward the study of cultural practices or varietal improvement. Only two improved varieties, `Borinquen' introduced by the Puerto Rico Agricultural Experiment Station in the 1940s and `La Primera' introduced by the Florida Agricultural Experiment Station in 1979 are available. Approaches to calabaza improvement including development of plants with shorter vines, incorporation of powdery mildew resistance, and production of uniform, symmetrical, hard-shelled, medium-sized fruit with enhanced nutritional quality in relationship to management systems are discussed.