1,720,983 research outputs found
Effects of Color to Deter Thrips and Reducing the Incidence of Tomato Spotted Wilt Virus
Full text linkA field study was conducted to evaluate the influence of colored mulch plastic on thrips ability to locate tomatoes (Lycopersicon esculentum Mill.). Mulch colors were selected based on ultra violet reflectance which has been shown to repel thrips. Specially manufactured colored mulches (Pliant Corp, Washington, GA) were: silver, red 1, red 2, black, and violet. Thrips population counts and plant yields were taken weekly. Enzyme-linked immunosorbent assay (ELISA) tests were completed early-season and mid-season to test for tomato spotted wilt virus (TSWV). Statistical anaylsis revealed that the colored mulches did effect thrips counts measured by cup and flower sampling, marketable weight, marketable count, and TSWV incidence. The silver colored mulch was consistently lower in cup counts of thrips than all other treatments and black mulch had the highest cup count of thrips. The silver mulch had the least number of flower thrips than any other treatment and the violet mulch had the highest flower thrips. Silver mulch had higher marketable weight and marketable fruit count then all other treatments followed by the violet mulch, but the violet mulch had less incidence of TSWV than the silver. The standard black mulch had the lowest marketable weight and marketable fruit count than all other treatments. In the later test for TSWV, red 1 and violet colored mulches similarly had the lowest percentage of TSWV incidence and black mulches had the highest percentage of TSWV incidence.
A field study was conducted to evaluate the influence of Blue-X Growtube Shelters on the ability of thrips to locate tomatoes (Lycopersicon esculentum Mill.). Blue-X Shelters (BLUE-X® Enterprises, Inc., Sacramento, CA) with varying tube sizes were selected for this study: 13”x9”, 13”x6”, 18”x9”, and 18”x6”, along with a non-treated control. Thrips population counts, yields, and height measurements were taken weekly. Enzyme-linked immunosorbent assay (ELISA) tests were completed early-season and mid-season to test for tomato spotted wilt virus (TSWV). Statistical anaylsis revealed that the Blue-X growtubes did lower thrips cup counts in the early season. No difference was seen in the flower counts taken later in the season. The marketable weight and marketable fruit counts were effected by the treatments. The non-treated control plots had the highest marketable fruit weight and marketable fruit counts over all the tube treatments. The 18”x6” and 18”x9” had the lowest marketable fruit weight and marketable fruit count. TSWV was highest in the 18”x6” tubes in the early season test than any other treatment. In the later testing 13”x6” tubes had the highest amount of TSWV incidence of any other treatment. Plant height was effected by the treatments. All tube treatments were taller than the control plots
Assessing Teacher Practices Related to Precision Agriculture in Secondary Agriculture Education
No full textAgricultural education was designed to reflect the agriculture industry, and since the recent
increase in technology use in the industry, little research has been done to investigate what
agricultural technologies are used in secondary agriculture classrooms. This study identifies the
curriculum involving precision agriculture that is currently being taught and gains insight into
teachers’ decisions to integrate precision agriculture in their classrooms. Secondary agriculture
instructors in Alabama and Illinois participated in this study and provided descriptive data about
their personal characteristics and their decision to incorporate precision agriculture, as well as
barriers that prevent them from incorporating precision agriculture concepts. Teachers indicated
the importance and relevance of precision agriculture, but only half of the participants
incorporate related concepts into their curricula. A Chi Square test revealed no significant
relationships between the personal characteristics of teachers and their decision to incorporate
precision agriculture concepts. The most important topics in precision agriculture were identified
by participants as GPS, Soil Sampling/Land Management and Genetic Modification. Teachers
indicated a need for professional development or teacher education focused on precision
agriculture in multiple fashions, which reflects the need for similar education in the agriculture
industry
Evaluation of Optimal Substrates and Fertilizers for Organic Vegetable Transplant Production in Alabama
Full text linkSuccessful organic vegetable production requires a healthy transplant. Presently, there are several certified organic plug substrate blends available; however, the suitability and cost of these substrates are a concern to growers who often report inconsistent or poor results. There is a need to evaluate available certified organic mixes to develop recommendations for organic transplant production that will provide consistent results. In Alabama, four economically important crops for organic growers are tomato (Lycopersicon esculentum Mill.), cucumber (Cucumis sativus L.), lettuce (Lactua sativa L.) and collards (Brassica oleracea (Acephala Group) L.).
Untreated seed of ‘Celebrity’ tomato and organically produced seed of ‘General Lee’ cucumber were sown July 2006. Organic seed of ‘Red Sails’ lettuce and untreated seed of ‘Georgia Southern’ collard were sown Oct. 2006. The design was a RCBD utilizing four substrates for a total of four treatments in four replicates. Each crop was grown in one of the following substrates in 72-cell plastic market trays: Fafard Organic Formula #10 (FO), Fafard 1P (FC), Sunshine Professional Organic Blend (SO), and Sunshine LC1 (SC). Upon emergence of the true leaves, seedlings grown in FO and SO were fertilized twice weekly with 50 ppm N with a 2N-1.7P-0.83K Neptune’s Harvest Fish Hydrolysate for a total of 100 ppm N per week (Gloucester, Mass.). Seedlings grown in FC and SC were fertilized twice weekly with 50 ppm N from a standard TotalGro 20N-4.4P-16.6K water-soluble fertilizer for a total of 100 pmm N per week (SDT Industries, Winnsboro, LA).
Five plants were randomly selected per plot and harvested weekly over a three to five week period depending on the crop. Data of a number of growth parameters were collected: plant canopy height, stem diameter, total leaf area, and total fresh and dry weights of each plant’s leaves, shoots, and roots to compare relative growth under each treatment.
By last harvest of tomato and cucumber, growth in FO was statistically similar to that in FC; for lettuce and collard, growth in SO was statistically similar to FC. Results suggest growers can produce organic transplants comparable to that of conventional system but that the selection of substrates may be crop dependent
Integration of Intensive Aquaculture and Horticulture Crop Production
No full textAgricultural sectors can be integrated into mutually beneficial productions
systems. Integration provides improved production sustainability, increased ecosystem
health, increased human health, and polyculture. Horticulture and aquaculture are two
sectors of agriculture readily integrated. Water-reuse, nutrient filtration, decreased
environmental loading, decreased production costs, and product diversification are
several benefits of irrigating horticulture crop production with aquaculture effluent
waters. The objective of studies was to evaluate horticulture crop production in an
intensive system utilizing aquaculture effluent water, as compared to standard greenhouse
horticulture crop production. Effluent water from an intensive tilapia production facility
was utilized as an alternative input to traditional greenhouse crop production. Tilapia
production was conducted in a 29.3 x 9.1 m (96 x 30 ft) double layer polyethylenecovered
greenhouse, for increased environmental control for year-round production. Fish
were stocked at 80 fish·m3, in two 27.4 m x 3.8 m x 1.2 m (90 ft x 12½ x 4 ft) tanks,
constructed of wood with steel I-beam and metal cable reinforcements. Due intensive
nature of aquaculture production, continuous aeration supplied adequate dissolved
oxygen (DO) for fish population. Dissolved oxygen and temperature of fish culture water
were recorded with YSI 550A meter (YSI Inc., Yellow Springs, OH). Culture water pH,
EC, and salinity were measured with YSI 63 meter. Tank water total ammonia nitrogen
(TAN) levels were measured with a test kit (1.0 to 8.0mg·L-1, LaMotte Company,
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Chestertown, MD), and NO3
--N was measured with ion specific electrode meter
(Cardy meter, range 0 to 9,900 mg·L-1, Spectrum Technologies, Inc., Plainfield, IL).
Water samples were collected weekly and analyzed using ICAP and for NH4
determination. Water exchange rate was between 4% and 12% daily per tank. Daily
feeding rate was between 27 kg to 34 kg (50 lbs to 75 lbs) feed·tank-1·day-1 with a 32%
crude protein fish feed (Alabama Catfish Feed Mill, Uniontown, AL).
Adjacent to the fish greenhouse, bedding plants and vegetables were irrigated
utilizing effluent water provided from the tank directly, or bypassed through a settling
tank as experiments required. All experiments were conducted in a 29.3 x 9.1 m (96 x 30
ft) greenhouse, with a double-layer polyethylene cover. The first experiment, conducted
between January to March 2009 and July to August, 2009, clear water (CW) and effluent
water (EW) irrigation was examined under varying types and rates of fertilizer inputs.
Clear water treatments included a soluble 200 mg N·L-1 application, and a top-dressed
controlled release fertilizer applied at 1.58 kg N·yd-3. Effluent water treatments varied
between settled EW and unsettled EW. Results indicate plants grown under effluent
water irrigation preformed similar to those produced under traditional production
methods. In the second experiment, conducted from July to September 2009, irrigation
source was again examined between CW and EW applications, while varying rates of a
soluble fertilizer were compared. Treatments consisted of 200 mg N·L-1, 100 mg N·L-1,
and unsettled EW. Results indicate plants grown under effluent water irrigation
preformed similar to those produced under traditional production methods. Two
experiments examined effects of EW irrigation on vegetable production. One study
investigated greenhouse production of a 90-day sweetcorn variety, while the second study
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examined production of hydroponic cucumbers, in both studies plant received CW and
EW irrigation as treatments. Results for the sweetcorn study, conducted January to March
2009, indicate no visual or statistical differences between treatments for plant height,
yield, ear weight and length. Results for the hydroponic cucumber study, conducted from
September to October 2009, indicate Manar F1 Beit Alpha cucumbers receiving EW
performed similarly to plants receiving a specially formulated hydroponic fertilizer for a
defined time frame, after which fruit production on plant irrigated with EW was less than
the yield of fruit from plants receiving CW. Results indicate intensive aquaculture
effluent water to be a viable irrigation source from production of plant species grown
Alternative Mulch Species, With and Without Dimethenamid-p, for Weed Control in Nursery Container Production
No full textWeed control has been a persistent problem in the nursery industry. These antagonistic weeds incur many challenges and cost to control them as well as reducing the container plants marketability (Neal, 1999; Simpson et al, 2002). The necessity to control weeds in container plant production has propelled two nursery management practices, hand pulling and herbicide applications. There are numerous problems associated with current weed control practices including increasing labor cost, herbicide resistant weeds, misapplications, injury to non-target plants, and environmental concerns. Mulches may have potential to be valuable assets in the struggle to reduce labor costs, effectively control weeds, and reduce the negative environmental impacts of current practices. Pine bark mini-nuggets, as with other tree-derived mulches, create an environment that is not conducive to weed seed germination due to low fertility, large particle size, and hydrophobic properties (Richardson et al., 2008). In other studies, combinations of herbicides and mulches were deemed most effective. In addition to tree-derived mulch materials such as pine bark, pine straw and hardwood chips, other readily available tree-derived mulch species such as Chinese privet (Ligustrum sinense), sweetgum (Liquidambar styraciflua), and eastern red cedar (Juniperus virginiana) could be used as mulch in container production in lieu of commercialized pine bark mini-nuggets. The objective of this study was to evaluate four readily available mulch species at multiple depths for long term weed control and phytotoxicity in container grown nursery plants. Mulch treatments were evaluated with and without dimethenamid-p herbicide (Tower®). All aforementioned mulches were tested at depths of 2.5, 5.1, or 10.2 cm (0, 1, 2, and 4 in), with and without dimethenamid-p herbicide, to determine if there were any differences among treatments through the duration of a growing season on weed counts and fresh weight of long-stalked phyllanthus (Phyllanthus tenellus), eclipta (Eclipta prostrata), and spotted spurge (Euphorbia maculata). At the first 30 day evaluation, there were no differences in treatments other than containers without mulch. Dimethenamid-p was shown to have better weed control without the addition of mulch than containers not treated with herbicide but did not increase efficacy when compared at 2.5, 5.1, or 10.2 cm (1, 2, or 4 in) of mulch. By the initiation of the second evaluation period (~45 days after treatment), dimethenamid-p had lost considerable weed control efficacy and mulch depth main effect remained significant through the third evaluation period (~160 days after treatment). Quadratic or linear trends over mulch depth indicated that weed control increased with mulch depth on all weed species across all evaluations. There were no consistent differences observed between mulch species. Mulch and herbicide effects on the growth of wax-leaf ligustrum (Ligustrum japonicum) and snowball viburnum (Viburnum macrocephalum) were evaluated separately. No phytotoxicity injury was observed at any date in the study. Plant size index indicated that dimethenamid-p treatments reduced the growth of both species by an average of 5 cm (1 in); mulch species or depth did not. Data showed that mulches prepared from any of these readily available tree species could be viable weed control options
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Combinations of Selected Sulfonylurea Herbicides and Diazinon for Yellow Nutsedge Control in Tomatoes
Full text linkIn 2008 and 2009 greenhouse and field studies were conducted at Auburn University’s Plant Science Research Center, E.V. Smith Research Station, and Wiregrass Research and Extension Center evaluating combinations of selected sulfonylurea herbicides with the organophosphate insecticide diazinon to determine their combined effect on yellow nutsedge (Cyperus esculentus) control.
In 2009, studies were conducted in the greenhouse to evaluate nutsedge emergence with select preemergence applications of halosulfuron, alone and in combination with diazinon. When combined with diazinon, halosulfuron resulted in rate-dependent reductions in yellow nutsedge emergence. A significant interaction was observed with the two pesticides, which suggests they may have a combined effect on yellow nutsedge control. The highest rate of halosulfuron combined with various rates of diazinon offered the greatest level of nutsedge control, ranging from 95 to 100 percent control.
In the summer of 2008, a field study was conducted to evaluate nutsedge biomass with preemergence, sprayed and injected, applications of halosulfuron and diazinon alone and combined. A significant interaction was observed between halosulfuron and diazinon. In the summer of 2009, a similar field study was conducted but the injected applications were eliminated due to no differences between sprayed and injected treatments. A synergistic interaction between the two pesticides was observed in the first study but not in the second.
In 2009, field studies were conducted to evaluate nutsedge biomass with preemergence combinations of halosulfuron and diazinon. Polyethylene mulch was applied to the second study while the first study was left bare ground. A synergism was not observed in either study. However, the most effective treatment in the second study was the low rate of halosulfuron combined with a high rate of diazinon.
In 2009, studies were conducted in the greenhouse to evaluate nutsedge emergence with select preemergence applications of trifloxysulfuron and diazinon alone and combined. In the second study, the highest rate of trifloxysulfuron combined with the highest rate of diazinon offered the greatest level of nutsedge control. A synergistic interaction was observed between the two pesticides in the second study, suggesting that ensuing research should be conducted in the field
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Mitigation of Hurricane Damage in Pecan Orchards
Full text linkHurricanes make landfall in the southeastern United States, the center of the majority of worldwide pecan production, on an annual basis. Hurricanes cause severe damage to orchards and reduce yield dramatically for years following. Defoliating pecan trees may mitigate injury caused by excessive rainfall and wind speeds of hurricanes by reducing the drag coefficient (CD) of the tree crown. Chemical defoliation was first developed for the cotton industry; however, it may have application in protecting pecan trees by reducing the CD below the major damage threshold. To determine the effectiveness of defoliation for reduction of CD in pecans, wind force measurements were recorded at five hand defoliation percentages. Results showed 50% defoliation equated to 50% reduction in midpoint wind pressure to 7.92 lbs/ft2, enough to avoid major limb breakage and uprooting according to the Coder Wind Scale. After preliminary screening, the safest and most effective defoliants were evaluated at varying mixtures and concentrations to determine percent defoliation efficacy with time. Thidiazuron (6.4 oz/100 gallons of water) with ethephon (3.2 oz/100 gallons of water) and chelated copper with urea ammonium nitrate (UAN) and a nonionic surfactant showed the highest defoliation percentages at 67% in 72 hours and 88% in 96 hours respectively. This series of studies establishes defoliating pecan trees prior to hurricane conditions could prevent breakage of major scaffold branches and uprooting
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