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Experiments were conducted to investigate the feasibility of biological control measures to control Western Flower Thrips. Thrips population and preferred trap color were examined using sticky trap tapes in 5 fluorescent colors, orange, yellow, green, blue and pink. Results indicated that pink is more effective in attracting thrips than the traditional yellow or the newly acclaimed blue sticky traps on the market now. Studies were also conducted to determine if the entomogenous nematode (Steinernema feltiae) could invade and parasitize Western Flower Thrips, and which stage of the thrips life cycle was most susceptible to parasitization. Thrips were dissected and checked for nematode invasion at 24, 48 and 72 hours after inoculation. S. feltiae was found to invade the body cavity after 24 hours in the larval stage of Western Flower Thrips resulting in death.

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Trichoderm a spp. are currently being investigated for biological control of soil-borne pathogens and their potential to enhance plant growth and development. The influence of T. harzianum and T. hamatum on growth of 7 bedding plant species was Investigated. Trichoderm a formulated in peat moss and wheat bran, was mixed into germination and growing media at 1 × 106 cfu per gram of medium. Seeds were germinated in plugs and later grown in cellpacks containing a treated and non-treated medium until market stage. Plants were evaluated by measuring height, fresh and dry weight, and number and timing of flowering. Growth enhancement was found in marigold (14.8% dw), petunia (15.5% dw) and tomato (38.2% dw), however, no significant differences were seen in celosia, impatiens, salvi a and vinca. Results suggest that growth enhancement by Trichoderm a is species dependent and that Trichoderm a applied in the plug mix remains-effective through marketing stage.

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Experiments were conducted to investigate the feasibility of biological control measures to control Western Flower Thrips. Thrips population and preferred trap color were examined using sticky trap tapes in 5 fluorescent colors, orange, yellow, green, blue and pink. Results indicated that pink is more effective in attracting thrips than the traditional yellow or the newly acclaimed blue sticky traps on the market now. Studies were also conducted to determine if the entomogenous nematode (Steinernema feltiae) could invade and parasitize Western Flower Thrips, and which stage of the thrips life cycle was most susceptible to parasitization. Thrips were dissected and checked for nematode invasion at 24, 48 and 72 hours after inoculation. S. feltiae was found to invade the body cavity after 24 hours in the larval stage of Western Flower Thrips resulting in death.

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Control failures of many insecticides used against the western flower thrips (WFT), Frankiniella occidentalis (Pergande), have been reported from several locations by greenhouse operators. To document resistance, thrips were bioassayed by placing them in vials coated with doses of diazinon, methomyl, bendiocarb, dimethoate, azinphosmethyl and cypermethrin at (100, 50, 10, 5, 1, 0.5 and 0.1 g/vial). Adult female WFT were collected from a colony exhibiting control failures using organophosphate, carbamate and pyrethroid insecticides. A colony showing no resistance was used as a control. The LC50's of the resistant and susceptible strains were diazinon 49.3 and 4.6 g/vial, cypermethrin no mortality and 3.7 g/vial, and azinphosmethyl 20.2 and 2.l g/vial respectively. Results show resistance is present as well as cross resistance to diazinon and cypermethrin because the resistant population was never exposed to these compounds.

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A set of 216 polymerase chain reaction-based molecular markers was screened for polymorphisms using two morphologically dissimilar broccoli (Brassica oleracea L. ssp. italica Plenck) lines, ‘VI-158’ and ‘‘Brocolette Neri E. Cespuglio’. Fifty-nine of these simple sequence repeat (SSR) and sequence-related amplified polymorphic (SRAP) primer pairs generated 69 polymorphisms that were used to construct a linkage map of broccoli from a population of 162 F2:3 families derived from the cross between these two lines. Ten linkage groups were generated that spanned a distance of 468 cM with an average interval width of 9.4 cM. The map was used to identify quantitative trait loci (QTL) associated with differences in harvest date maturity and head weight in the population grown in the same location over 2 years. Heritability estimates for days to maturity and head weight were 0.84 and 0.64, respectively. Four QTL for harvest maturity were identified that described 55.6% of the phenotypic variation in the first year with two of these QTL also detected in the second year of the experiment that described 29.2% of the phenotypic variation. Five QTL were identified as associated with head weight in 1999 and accounted for 71.8% of the phenotypic variability. Two of these QTL accounted for 24% of the phenotypic variability in head weight in 2000. To our knowledge, this is the first linkage map of broccoli and the first combined SSR and SRAP map of B. oleracea, which should provide a useful tool for the genetic analysis of traits specific to ssp. italica.

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Field studies were conducted in 1987 and 1988 to determine the effect of various sprinkler-applied N-K fertigation treatments and 196N-280K (kg·ha-1) dry-blend application on pumpkin (Cucurbita moschata Poir.) flower development, fruit set, vine growth, and marketable yield response in a Plainfield sand. The number of male and female flowers that reached anthesis by 72 days after seeding (DAS) was highest with either 112N-112K or 112N-224K fertigation. Fertigation using either 56N-112K or 168N-224K delayed the start of flowering and reduced the total number of male and female flowers produced by 72 DAS. Fruit set decreased at the low N-K fertigation rate (56N-112K), but otherwise was unaffected by N-K fertility regime. Vine dry weight and stem elongation increased as the N fertigation rate increased, with relatively little effect from fertigated K. There was no field indication of excessive vegetative growth in any of the fertigation treatments. Highest yields of early set marketable fruit (pumpkins that set before 65 DAS), and total marketable yields were obtained with fertigation of 112N, in combination with either 112 or 224 kg·ha-1 fertigated K. Usable green and cull fruit production increased with increasing N-K fertigation rate. Dry-blend application of 196N-280K decreased early and total yields significantly. The results showed that sprinkler-applied 112N-112K split into five fertigations during the growing season (supplemented with a preplant dry-blend application of 28N-56K) produced high yields without compromising early fruit maturity.

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Light-emitting diodes (LEDs) are a potential irradiation source for intensive plant culture systems and photobiological research. They have small size, low mass, a long functional life, and narrow spectral output. In this study, we measured the growth and dry matter partitioning of `Hungarian Wax' pepper (Capsicum annum L.) plants grown under red LEDs compared with similar plants grown under red LEDs with supplemental blue or far-red radiation or under broad spectrum metal halide (MH) lamps. Additionally, we describe the thermal and spectra1 characteristics of these sources. The LEDs used in this study had a narrow bandwidth at half peak height (25 nm) and a focused maximum spectral output at 660 nm for the red and 735 nm for the far-red. Near infrared radiation (800 to 3000 nm) was below detection and thermal infrared radiation (3000 to 50,000 nm) was lower in the LEDs compared to the MH source. Although the red to far-red ratio varied considerably, the calculated phytochrome photostationary state (φ) was only slightly different between the radiation sources. Plant biomass was reduced when peppers were grown under red LEDs in the absence of blue wavelengths compared to plants grown under supplemental blue fluorescent lamps or MH lamps. The addition of far-red radiation resulted in taller plants with greater stem mass than red LEDs alone. There were fewer leaves under red or red plus far-red radiation than with lamps producing blue wavelengths. These results indicate that red LEDs may be suitable, in proper combination with other wavelengths of light, for the culture of plants in tightly controlled environments such as space-based plant culture systems.

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Abstract

Cropping systems were compared among vegetable crops which are commonly grown for profit on a 5–10 ha farm. Tomato [Lycopersicon esculentum (Mill.) ‘Jet Star’], cabbage [Brassica oleracea (L.) var. capitata ‘Sunup’], collards [Brassica oleracea (L.) var. acephala ‘Vates’], and muskmelon [Cucumis melo (L.) ‘Gold Star’] were monocropped; cabbage was intercropped with tomatoes; and collards were intercropped with muskmelon. Crop yield, production cost, and economic returns of the intercrop system were comparable to those of the crops produced alone.

Open Access

Abstract

Double-cropping systems were compared to the same vegetable monocropped. Snap beans [Phaseolus vulgaris (L.) ‘Bush Blue Lake’], sweet corn [Zea mays (L.) ‘Sundance’], cauliflower [Brassica oleracea (L.), Botrytis group, ‘Snow Crown’], summer squash [Cucurbita pepo (L.) ‘Zucchini Elite’], and broccoli [Brassica oleracea (L.), Italica group, ‘Green Comet’] were used. The double-crop systems used were spring snap bean and fall cauliflower, summer squash and fall broccoli, and spring sweet corn and fall snap beans. The monocrop system was used as a control for the double-crop systems. The greatest net returns were: 1) squash monocropped or squash/broccoli double-cropped, 2) squash double-cropped, 3) cauliflower or cauliflower/snap bean double-cropped, and 4) broccoli or cauliflower or snap beans monocropped. Fall snap beans provided the least economic return. The double-cropping system allows an option of crop production with a potential increase in yield and economic returns using half the amount of land per year required for either crop grown in monoculture. In addition, these systems reduce the risk of economic failure during a year of low-market demand for either crop grown alone.

Open Access

Physical and biological parameters affecting the efficiency of biolistic transformation of peach were optimized using ß-glucuronidase (GUS) as a reporter gene, such that efficiency of transient GUS expression in peach embryo-derived callus was increased markedly. Transient expression was also obtained in embryonic axes, immature embryos, cotyledons, shoot tips, and leaves of peach. Stable expression of a fusion gene combining neomycin phosphotransferase (NPTII) and ß-glucuronidase activities has been achieved in peach embryo calli. Sixty-five kanamycin-resistant callus lines were obtained from 114 pieces of bombarded calli after 4 months of selection. Nineteen of the 65 putative transformant lines produced shoot-like structures. Seven lines were examined to confirm stable transformation using the colorimetric GUS assay and PCR analysis. All seven lines showed GUS activity. PCR analysis confirmed that, in most of the putative transformants, the chimeric GUS/NPTII gene had been incorporated into the peach genome. The transgenic callus lines were very weakly morphogenic, presumably because the callus was 5 years old and no transgenic shoots developed from this callus. Results of this research demonstrate the feasibility of obtaining stable transgenic peach tissue by biolistic transformation.

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