Search Results

You are looking at 1 - 10 of 11 items for

  • Author or Editor: James Taylor x
Clear All Modify Search

Abstract

Various histological criteria were employed in studying the chronological and morphological development of the apex of field-grown plants of Brassica oleracea var. italica, cv. ‘Coastal’. Time of differentiation was based on changes in the size and configuration of the apex. The earliest evidence of reproductive differentiation was 5 weeks after sowing or at the time of macroscopic appearance and unfolding of the eighth true leaf. First order floral stalks began to appear at 7 weeks or at the time of macroscopic appearance of the 14th true leaf. Thus, the time interval for the transition from a vegetative to a reproductive apex appears to be approximately 2 weeks, under field conditions. By 9 weeks after sowing, or after the macroscopic appearance of the 22nd true leaf, second order floral stalk initiation and hence inflorescent head formation predominated.

Open Access

Abstract

Environmental growth chamber studies were employed to determine the influence of temperature, daylength, and seed vernalization on reproductive differentiation of the shoot apex and subsequent formation of the inflorescent head or “button”. Under the conditions employed, low temperature alone did not directly influence differentiation or button formation. However, low temperature markedly retarded vegetative growth so that the plant underwent differentiation and formed buttons at a younger morphological age. Low temperature had no influence on the chronological time of differentiation or button formation except under continuous light. Therefore, in studying the influence of temperature on flowering, a chronological index should be used alone or conjointly with a morphological index.

Under continuous light, seed vernalization or low ambient plant growing temperatures resulted in both chronological and morphological earliness of differentiation and subsequent button formation. It is suggested from these results that a low temperature-mediated phytochrome system may play a part in the control mechanism for flowering of green sprouting broccoli.

Open Access

Aphids cause major annual economic losses to the U.S. pecan [Carya illinoinensis (Wangenh.) K. Koch] industry and are becoming harder to control with standard pesticides. An evaluation of efforts by certain growers to suppress aphid populations using air-blast sprays of 0.05% Silwet L-77, a non-ionic super-wetting organosilicone surfactant, indicated that: 1) reductions in blackmargined aphid [Monellia caryella (Fitch)] levels were mostly attributable to the air-blast spray effect rather than to the Silwet L-77 component; 2) a 0.05% solution of Silwet L-77 reduced net photosynthesis (A) of foliage by 5% for at least 14 days post-treatment; and 3) the efficacy of 0.05% Silwet L-77 sprays is not substantially increased by doubling the volume of spray per tree (1868 L·ha-1). However, higher Silwet L-77 concentrations were highly effective in killing aphids, although there was little or no residual activity. A response curve indicated that air-blast sprays of orchard trees with 0.30% (v/v) Silwet L-77 (at 934 L·ha-1) are capable of reducing yellow pecan aphid (Monelliopsis pecanis Bissell) populations by at least 84% while only reducing A by ≤10%. Chemical names used: silicone-polyether copolymer (Silwet L-77).

Free access

Commercial organic vegetable production requires using soil improvement practices and effective weed control measures. Rye (Secale cereale) cover crops are known to suppress annual weeds. Research was begun in 2004 to measure crop yield, annual weed infestation, and weed control requirements for vegetable planting systems that begin with a rye cover crop. Poultry litter was used to supply nutrients and was applied based on a soil test and commercial vegetable recommendations. Rye `Elbon' was seeded 21 Oct. 2004 on beds with 1.8-m centers. Zucchini squash (Cucurbita pepo) `Revenue' was planted the following year using three crop establishment dates, such that transplanting occurred on 6 May, 3 June, and 29 June. Planting system treatments included: conventional tillage (CT), CT and plastic mulch (P), CT with stale seedbed, mow, mow and burn-down, mow and shallow till (ST), ST and burn-down. Following field preparation, squash was transplanted in a single row at the bed center with 0.77-m plant spacing. Drip irrigation was used in all plantings. Emerging weeds were removed by hoeing. Squash was harvested from each planting over approximately 3 weeks and total marketable fruit counts were determined. Marketable yields with P were approximately double those of the CT and ST treatments in the 6 May transplanting. Yields were comparable for CT and ST in the 3 June transplanting, but were significantly lower for the P treatment. There were no significant differences among the treatments that received tillage in the 29 June planting. However, the non-tilled treatments had significantly lower yields compared to tilled treatments.

Free access

Published statistics on the spatial variation of fruit quality observed in orchards has been rudimentary to date. Dry matter and fruit weight data were collected spatially within 11 kiwifruit (Actinidia deliciosa var. deliciosa ‘Hayward’) orchards in the Bay of Plenty, New Zealand, to characterize the variability in fruit quality in terms of nonspatial and spatial statistics. Fruit weight was statistically more variable and exhibited a stronger spatial structure than the dry matter data. Individual variograms were derived for each orchard and then all the data were collated into average variograms for both quality attributes. The average variogram parameters were used to determine the optimum spacing for grid sampling to achieve a desired level of confidence when interpolating the data. A grid spacing of 28 m appears suitable for mapping fruit quality, provided sufficient area exists to collect enough points to perform block kriging. Plots of individual orchard and average variograms, and a table of nonspatial and variogram statistics are presented as a reference for future work in this area.

Free access

Squash (Cucurbita pepo) producers could benefit from additional herbicide options that are safe to the crop and provide effective weed control. Research was conducted in southeastern Oklahoma (Atoka County, Lane, OK) during 2010 and 2011 to determine the impact of pelargonic acid (PA) on weed control efficacy, crop injury, and squash yields. The experiment included PA applied unshielded postdirected at 5, 10, and 15 lb/acre, plus an untreated weedy control and an untreated weed-free control. ‘Enterprise’ yellow squash was direct-seeded in single rows into raised beds. Weeds included smooth crabgrass (Digitaria ischaemum), cutleaf groundcherry (Physalis angulata), spiny amaranth (Amaranthus spinosus), and yellow nutsedge (Cyperus esculentus). Pelargonic acid was applied each year in mid-July and then reapplied 8 days later. The maximum smooth crabgrass control (98%), broadleaf weed control (94%), and yellow nutsedge control (41%) was observed with the 15-lb/acre PA treatment at 9 days after initial spray treatment (DAIT), 1 day after sequential treatment (1 DAST). Pelargonic acid at 15 lb/acre provided equal or slightly greater smooth crabgrass and broadleaf (cutleaf groundcherry and spiny amaranth) control compared with the 10-lb/acre application, and consistently greater control than the 5-lb/acre rate and the weedy control. Pelargonic acid was less effective at controlling yellow nutsedge than smooth crabgrass and broadleaf weeds. Yellow nutsedge control peaked at 9 DAIT (1 DAST) with 10-lb/acre PA (41%). As the rate of PA increased from 5 to 15 lb/acre, yellow nutsedge control also increased significantly for all observation dates, except for 28 DAIT. Increasing the PA application rate increased the crop injury rating at 1 and 3 days after each application (1 and 3 DAIT, 1 and 3 DAST). Maximum squash injury occurred for each application rate at 9 DAIT (1 DAST) with 4.4%, 8.0%, and 12.5% injury for PA rates 5, 10, and 15 lb/acre, respectively. The 10-lb/acre PA treatment produced the highest squash yields (kilograms per hectare) and fruit number (fruit per hectare) compared with either the 5- or 15-lb/acre rates, and equivalent yields and fruit number as the hand-weeded weed-free treatment. The 10-lb/acre PA rate applied in a timely sequential application has the potential of providing good weed control with minimal crop injury resulting in yields equivalent to weed-free hand-weeding conditions.

Full access

Pepper (Capsicum annuum) producers would benefit from additional herbicide options that are safe to the crop and provide effective weed control. Research was conducted in southeastern Oklahoma (Atoka County, Lane, OK) during 2010 and 2011 to determine the impact of pelargonic acid on weed control efficacy, crop injury, and pepper yields. The experiment included pelargonic acid applied unshielded postdirected at 5, 10, and 15 lb/acre, plus an untreated weedy control and an untreated weed-free control. ‘Jupiter’ sweet bell pepper, a tobacco mosaic virus-resistant sweet pepper with a 70-day maturity, was transplanted into single rows on 3-ft centered raised beds with 18 inches between plants (9680 plants/acre) on 28 May 2010 and 27 May 2011, respectively. Weeds included smooth crabgrass (Digitaria ischaemum), cutleaf groundcherry (Physalis angulata), spiny amaranth (Amaranthus spinosus), and yellow nutsedge (Cyperus esculentus). Pelargonic acid was applied postdirected each year in mid-June and then reapplied 8 days later. The 15-lb/acre pelargonic acid treatment resulted in the maximum smooth crabgrass control (56%) and broadleaf weed control (66%) at 1 day after the initial spray treatment (DAIT), and 33% yellow nutsedge control at 3 DAIT. Pelargonic acid at 15 lb/acre provided equal or slightly greater smooth crabgrass and broadleaf (cutleaf groundcherry and spiny amaranth) control compared with the 10-lb/acre application, and consistently greater control than the 5-lb/acre rate and the weedy control. Pelargonic acid was less effective at controlling yellow nutsedge than smooth crabgrass and broadleaf weeds. As the rate of pelargonic acid increased from 5 to 15 lb/acre, yellow nutsedge control also increased significantly for all observation dates. Increasing the pelargonic acid application rate increased the crop injury rating. The maximum crop injury occurred for each application rate at 1 DAIT with 7%, 8.0%, and 13.8% injury for pelargonic acid rates 5, 10, and 15 lb/acre, respectively. There was little or no new crop injury after the second postdirected application of pelargonic acid and crop injury following 3 DAIT for application rates was 2% or less. Only the 15-lb/acre pelargonic acid application produced greater fruit per hectare (4784 fruit/ha) and yields (58.65 kg·ha−1) than the weedy control (1196 fruit/ha and 19.59 kg·ha−1). The weed-free yields (7176 fruit/ha, 178.11 kg·ha−1, and 24.82 g/fruit) were significantly greater than all pelargonic acid treatments and the weedy control. Pelargonic acid provided unsatisfactory weed control for all rates and did not significantly benefit from the sequential applications. The authors suggest the pelargonic acid be applied to smaller weeds to increase the weed control to acceptable levels (>80%).

Full access

Corn gluten meal (CGM) is a non-selective preemergence or preplant-incorporated herbicide that inhibits root development, decreases shoot length, and reduces plant survival. The development of a mechanized application system for the banded placement of CGM between crop rows (seed row not treated) has increased its potential use in organic vegetable production, especially in direct-seeded vegetables. The objective of this research was to determine the impact of CGM applications (formulations, rates, incorporation, and banded applications) on direct-seeded squash (Cucurbita pepo) plant survival and yields. Neither CGM formulation (powdered or granulated) nor incorporation method (incorporated or non-incorporated) resulted in significant differences in plant survival or squash yields. When averaged across all other factors (formulations, incorporation method, and banding), CGM rates of 250 to 750 g·m−2 reduced squash survival from 70% to 44%, and squash yields from 6402 to 4472 kg·ha−1. However, the banded application (CGM placed between rows) resulted in significantly greater crop safety (75% survival) and yield (6402 kg·ha−1) than the broadcast (non-banded) applications (35% survival and 4119 kg·ha−1 yield). It was demonstrated that banded applications of CGM can be useful in direct-seeded squash production and other organic direct-seeded vegetables.

Full access

An interdisciplinary team of Clemson Univ. faculty, graduate students, and undergraduate students partnered with the South Carolina Botanical Garden staff and children from the “Sprouting Wings” after-school garden program to plan and design a 2.5-acre Children's Garden. Imaginative and educational, the plans call for a series of outdoor theme gardens. Proposals for 13 theme gardens include a “Dinosaur Dig”, a “Food for Thought Garden”, a “Hide-and-Seek Garden”, a “Terraced Sitting Garden”, an “Ethnobotany Garden”, a “Wonders of Water Garden”, a “Learning from Nature Outdoor Classroom”, a “Carolina Fence Garden”, a “Cottage Garden”, a “Bold View Butterfly Garden”, a “Woodland Wonderland”, a “Playful Plaza Garden,” and an “Arbored Entrance and Exit Garden.” Project methodology included research, case studies, site analysis, program development, preliminary plans, master plan, and individual garden designs with plan views, elevation drawings, detail drawings, and plant lists. Using an experiential learning pedagogy, a design class of 15 students contributed an estimated 2,000 hours of work while learning about landscape design. Results included 30 drawing boards depicting research, analysis, and design proposals, which were presented to the South Carolina Botanical Garden Staff for approval in Fall 2003. Note: This material is based upon work supported by the cooperative State Research, Education, and Extension service, U.S. Dept. of Agriculture, under Agreement No. 2002-38411-122122. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the authors and do not necessarily reflect the view of the U.S. Dept. of Agriculture.

Free access