bluuebunny/crossref_metadata_2025 huggingface dataset:
Harvest Mechanization Progress and Prospects for Fresh Market Quality Deciduous Tree Fruits
Authors: Peterson D.L.
Published: December 2018

Deciduous tree fruit crops such as apple (Malus domestica), peach (Prunus persica), and sweet cherry (Prunus avium) are not mechanically harvested for the fresh market. Attempts to mechanically harvest these fruits by mass removal techniques have not been successful due to excessive fruit damage caused during detachment, fall through the canopy, and collection. Robotic harvesters have not been commercially accepted due to insufficient fruit recovery. A U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS) harvesting concept shows promise for harvesting both fresh market quality apples and sweet cherries. Successful mechanical harvesting of fresh market quality deciduous tree fruit will only occur when plant characteristics and machine designs are integrated into a compatible system. Cultivar characteristics that would facilitate machine harvesting are uniform fruit maturity at harvest, firm fruit that are resistant to mechanical damage, and compact growth habit that produces fruit in narrow canopies and on short/stiff limbs. Engineers must develop new detachment principles that minimize the energy input to effect fruit detachment, and develop durable energy-absorbing catching surfaces/conveyors to eliminate damage during collection of the fruit. As technology advances, sorting and sizing systems might be developed that can be operating on the harvester to eliminate culls in the field and deliver only fresh market quality fruit to the packers.
Engineering Aspects of Production and Harvest Mechanization for Fresh and Processed Vegetables
Authors: Glancey James L. , Kee W. Edwin
Published: December 2018

Production and harvesting systems for processing vegetables have been highly mechanized, however, field efficiencies are generally low, and high field losses and fruit damage continue to limit profits for several crops. By comparison, the number of fresh market crops currently machine harvested is small, and research to develop new harvesting technology for these crops is limited. Current mechanization research includes improvements to existing production systems, development of harvesters for crops currently hand-harvested, and the integration of new technologies into current (and future) production systems. Mechanical harvester-based production systems are evolving that reduce field losses and fruit damage, improve recovery, and decrease the foreign materials in the harvested product. However, improved cultural production systems and crop varieties that are adapted for once-over machine harvest are needed. An integrated approach in which crop characteristics along with planting, cultivating, and harvesting techniques are considered will be necessary to develop profitable and highly efficient alternatives to hand-harvest production. The integration of new technologies including differential global positioning systems (DGPS), automatic machine guidance, and computer-based vision systems offers significant performance benefits, and is a substantial component of current vegetable production and harvesting research in the U.S. In time, as the costs of these technologies decline, commercial adoption of these new methods is expected to increase.
Salinity Effects on Florida Grapefruit in the Indian River Region
Authors: Boman Brian J.
Published: December 2018

A study was initiated in the 1997-98 production season to evaluate the effects of salinity on grapefruit yield and fruit quality in the Indian River area of Florida. The experiment was conducted on `Ray Ruby' grapefruit (Citrus paradisi) planted in 1990 on `Carrizo' citrange (C. sinensis × Poncirus trifoliata) and `Swingle' citrumelo (C. paradisi × P. trifoliata) rootstocks. Trees were planted on 15.2-m-wide (50 ft) double-row beds at a spacing of 4.6 m (15 ft) in-row × 7.3 m (24 ft) across-row [286.6 trees/ha (116 trees/acre)]. The control treatment was irrigated via microsprinkler emitters with water from a surficial aquifer well with an electrical conductivity (EC) of 0.7 dS·m-1. Higher irrigation water salinity levels were achieved by injecting a sea water brine mixture into the supply water to achieve ECs of 2.3, 3.9, and 5.5 dS·m-1. A wide range of rainfall and irrigation conditions occurred during the years encompassed by these studies, with rain totaling 1262, 1294, 1462, and 964 mm (49.7, 50.9, 57.6, and 38.0 inches) for 1997, 1998, 1999, and 2000, respectively. Salinity level had little effect on internal juice quality parameters [total soluble solids (TSS), acid, or juice content] at time of harvest. One of the most visible effects of irrigation with high salinity water was the damage to leaves, with leaf chloride (Cl) levels increasing about 0.14% for each 1.0 dS·m-1 increase in EC of the irrigation water for trees on `Carrizo' citrange and 0.02% for trees on `Swingle' citrumelo. For both rootstocks, the number of fruit and the size of the fruit decreased with increasing salinity in the irrigation water. The non-salinized trees had significantly larger fruit compared to the rest of the treatments. In the very dry 2000-01 season, trees on `Carrizo' irrigated with 0.7 dS·m-1 water had about 50% more fruit size 36 [fruit count per 0.028-m3 (4/5 bu) carton] or larger than trees watered with 3.9 or 5.5 dS·m-1 water. For trees on `Swingle' rootstock, trees irrigated with 0.7 dS·m-1 water had 150% to 200% more size 36 and larger fruit than trees watered with 2.3 dS·m-1 water. Over the four seasons, average yields for `Carrizo' were reduced 3200.0 kg·ha-1 (2855 lb/acre) per year for each 1.0 dS·m-1 increase in EC of the irrigation water. For `Swingle' rootstock, the reduction was 2600.3 kg·ha-1 (2320 lb/acre) per year for each 1.0 dS·m-1 increase in EC of the irrigation water. These reductions averaged 7% (`Swingle') and 6% (`Carrizo') for each 1.0 dS·m-1 increase in salinity of the irrigation water.
How Salinity Damages Citrus: Osmotic Effects and Specific Ion Toxicities
Authors: Ferguson Louise , Grattan Steven R.
Published: December 2018

There are two ways salinity can damage citrus: direct injury due to specific ions, and osmotic effects. Specific ion toxicities are due to accumulation of sodium, chloride, and/or boron in the tissue to damaging levels. The damage is visible as foliar chlorosis and necrosis and, if severe enough, will affect orchard productivity. These ion accumulations occur in two ways. The first, more controllable and less frequent method, is direct foliar uptake. Avoiding irrigation methods that wet the foliage can easily eliminate this form of specific ion damage. The second way specific ion toxicity can occur is via root uptake. Certain varieties or rootstocks are better able to exclude the uptake and translocation of these potentially damaging ions to the shoot and are more tolerant of salinity. The effect of specific ions, singly and in combination, on plant nutrient status can also be considered a specific ion effect. The second way salinity damages citrus is osmotic effects. Osmotic effects are caused not by specific ions but by the total concentration of salt in the soil solution produced by the combination of soil salinity, irrigation water quality, and fertilization. Most plants have a threshold concentration value above which yields decline. The arid climates that produce high quality fresh citrus fruit are also the climates that exacerbate the salt concentration in soil solution that produces the osmotic effects. Osmotic effects can be slow, subtle, and often indistinguishable from water stress. With the exception of periodic leaching, it is difficult to control osmotic effects and the cumulative effects on woody plants are not easily mitigated. This review summarizes recent research for both forms of salinity damage: specific ion toxicity and osmotic effects.
Managing Salinity in Citrus
Authors: Boman Brian J. , Zekri Mongi , Stover Ed
Published: December 2018

Although citrus (Citrus spp.) is sensitive to salinity, acceptable production can be achieved with moderate salinity levels, depending on the climate, scion cultivar, rootstock, and irrigation-fertilizer management. Irrigation scheduling is a key factor in managing salinity in areas with salinity problems. Increasing irrigation frequency and applying water in excess of the crop water requirement are recommended to leach the salts and minimize the salt concentration in the root zone. Overhead sprinkler irrigation should be avoided when using water containing high levels of salts because salt residues can accumulate on the foliage and cause serious injury. Much of the leaf and trunk damage associated with direct foliar uptake of salts can be reduced by using microirrigation systems. Frequent fertilization using low rates is recommended through fertigation or broadcast application of dry fertilizers. Nutrient sources should have a relatively low salt index and not contain chloride (Cl) or sodium (Na). In areas where Na accumulates in soils, application of calcium (Ca) sources (e.g., gypsum) has been found to reduce the deleterious effect of Na and improve plant growth under saline conditions. Adapting plants to saline environments and increasing salt tolerance through breeding and genetic manipulation is another important method for managing salinity.
Relocating Large Trees for Germplasm Conservation in Tree Fruit Breeding Programs
Authors: Hunter David M. , Gadsby Martin F.
Published: December 2018

Mature seedling trees of pear (Pyrus communis and interspecific hybrids), and fruiting trees of peach and nectarine (Prunus persica), apricot (Prunus armeniaca), and pear were relocated during the dormant season using tree spades. During the growing season immediately following, some signs of drought stress were noticed but all trees grew well enough that they could be used as a source of budwood for limited propagation purposes. When drip irrigation was supplied, supplemented by overhead irrigation as required, normal growth and production resumed within two growing seasons of the move. Some tree losses (less than 10% of trees moved) were reported from one site where the soil type was Fox sand with very poor water holding capacity. These tree losses were attributed to an inadequate water supply to the root ball, even though the site was irrigated. Our experience has demonstrated the feasibility of relocating relatively large trees, which can be beneficial for germplasm conservation in a tree fruit breeding program. However, it is probably not economically viable to relocate such trees for commercial production.
The Weed Control Potential of Oat Cultivars
Authors: Grimmer Orion P. , Masiunas John B.
Published: December 2018

Winter-killed oats (Avena sativa) may have potential for use to suppress weeds in early seeded crops such as pea (Pisum sativum). Residue biomass and surface coverage are generally correlated with weed suppression. Oat residues also contain allelochemicals. Our objective was to determine if oat cultivars vary in residue production and allelopathy. Differences between oat cultivars were observed in residue production, and for effects on emergence of common lambsquarters (Chenopodium album) and shepherd's-purse (Capsella bursa-pastoris) in the greenhouse, and germination of pea and common lambsquarters in an infusion assay. Two of the oat cultivars producing the greatest biomass, `Blaze' (in the field) and `Classic' (in the greenhouse), interfered minimally with pea germination and were among the best cultivars in inhibiting common lambsquarters and shepherd's-purse. `Blaze' also greatly inhibited common lambsquarters germination in the infusion assay that measured allelopathy. Thus, `Blaze' and `Classic' possess suitable characteristics for use as a cover crop preceding peas.
Effect of Ozonated Water on Creeping Bentgrass Growth in a Sand Medium
Authors: Sloan John J. , Engelke M.C.
Published: December 2018

Irrigation of sand-based golf greens with ozonated water may affect grass growth and chemical processes in the root zone. The objective of this study was to evaluate the effects of ozonated and aerated water on bentgrass growth and root zone chemistry in sand-based greens over a 12-month period. Creeping bentgrass (Agrostis stolonifera) cores [10 cm diameter × 12 cm depth (3.9 × 4.7 inches)] were collected from a sand-based bentgrass nursery and placed in columns designed to collect leachate water. Cores were placed in a greenhouse and irrigated with 1) municipal tap water [6 to 8 mg·L-1 (ppm) dissolved oxygen (DO)], 2) aerated tap water (12 mg·L-1 DO), or 3) ozonated tap water (aerated plus 0.8 mg·L-1 ozone). Leachate was periodically collected and analyzed for pH, electrolytic conductivity (EC), and nutrients. Grass clippings were weighed and analyzed for total nitrogen (N) and phosphorus (P). Roots were periodically collected from selected cores to determine root distribution. At 40 and 90 days after initiating water treatments, bentgrass irrigated with ozonated water had a higher chlorophyll index than bentgrass irrigated with tap water. After 128 and 157 days, bentgrass clipping weights were significantly greater for the cores irrigated with ozonated water and, to a lesser extent, aerated water. At 61 and 149 days, nitrate (NO3-N) and EC levels were elevated in leachate from aerated and ozonated samples, suggesting increased mineralization of organic matter in those bentgrass cores. Ozonated water increased bentgrass crown weights, but had no effect on root mass. Ozonated water did not affect bentgrass tissue N and P concentrations. Statistically significant effects from ozonated water occurred within the first few months, but sustained benefits were negligible.
Prompt Cooling Reduces Incidence and Severity of Decay Caused by Botrytis cinerea and Rhizopus stolonifer in Strawberry
Authors: Nunes M.C.N. , Morais A.M.M.B. , Brecht J.K. , Sargent S.A. , Bartz J.A.
Published: December 2018

Delays in initiating the cooling of freshly harvested `Chandler' strawberries (Fragaria ×ananassa) were compared with prompt cooling to determine how such handling affected development of postharvest decays during subsequent storage and marketing. Strawberries at the three-quarter to full red ripeness stages were harvested four times between mid-June and late July, inoculated with Botrytis cinerea or Rhizopus stolonifer and then handled to simulate prompt or delayed precooling prior to storage. This was done by incubating fruit at 35 °C (95.0 °F) and 70% to 80% relative humidity (RH) for 1 or 6 hours. The fruit were then forced-air cooled to 5 °C (41.0 °F) in 1 hour and stored for 7 days at 2 °C (35.6 °F) and 85% to 95% RH, plus displayed in a simulated market at 20 °C (68.0 °F) and 85% RH for 1 day. Decay incidence increased as the season progressed. For non-inoculated fruit, prompt cooling reduced the incidence of decay by an average of 25% and the decay severity by ∼24%. With inoculated fruit, prompt cooling resulted in 15% and 29% decreases in the incidence and severity, respectively, of rhizopus rot compared to delayed cooling, and 5% and 22% decreases in the incidence and severity, respectively, of botrytis rot. Overall, the incidence of botrytis and rhizopus fruit rot averaged 60% and 85% in the prompt and delayed cooling treatments, respectively. Although prompt cooling is important for minimizing postharvest decay of strawberries, temperature management alone may not sufficiently control postharvest decay when decay pressure is high.
Use of High-pressure Injection to Alleviate Type-I Fairy Ring Symptoms in Turfgrass
Authors: Fidanza M.A. , Colbaugh P.F. , Engelke M.C. , Davis S.D. , Kenworthy K.E.
Published: December 2018

Fairy ring is a common and troublesome disease of turfgrasses maintained on golf course putting greens. Type-I fairy ring is especially destructive due to the development of hydrophobic conditions in the thatch and root zone, thus contributing to turfgrass injury and loss. The objective of this 2-year field study was to evaluate the application and novel delivery method of two fungicides and a soil surfactant for curative control of type-I fairy ring in a 20-year-old creeping bentgrass [Agrostis palustris (synonym A. stolonifera)] putting green. In both years, all treatments were applied twice on a 28-day interval. In 1998, flutolanil and azoxystrobin fungicides were applied alone and in combination with Primer soil surfactant by a conventional topical spray method, and fungicides without Primer applied via high-pressure injection (HPI). Acceptable type-I fairy ring control was observed in plots treated with flutolanil plus Primer, HPI flutolanil, azoxystrobin alone, azoxystrobin plus Primer, or HPI azoxystrobin. In 1999, treatments were HPI flutolanil, HPI flutolanil plus Primer, HPI azoxystrobin, HPI water only, and aeration only. Acceptable type-I fairy ring control was observed in plots treated with HPI flutolanil plus Primer or HPI azoxystrobin. HPI of fungicides alone or in combination with a soil surfactant may be a viable option for alleviating type-I fairy ring symptoms on golf course putting greens.
Comparison of Four Production Systems for Dutch Iris in a Tobacco Transplant Greenhouse
Authors: Niedziela Carl E. , Mullins Christopher D. , Reed T. David , Swallow William H. , Eberly Eric
Published: December 2018

Pre-cooled bulbs of two dutch iris (Iris ×hollandica) cultivars, Ideal and White Wedgewood, were grown and harvested as cut flowers in four production systems in a tobacco (Nicotiana tabacum) transplant greenhouse from late October until late January in two consecutive production years (2000-01 and 2001-02). All production systems (lily crates, lay-flat bags, pots, and float trays) utilized the same commercial peat-vermiculite, tobacco germination substrate. Stems developed more quickly but were shorter and lighter in 2001-02 than 2000-01 due to warmer growing conditions. Stems grown in float trays were shorter and lighter than other treatments in 2000-01 but similar to the others in 2001-02. Stems grown in lay-flat bags flowered earlier with similar or greater stem lengths and fresh weights as the other systems. Stems of `White Wedgewood' were longer and heavier than `Ideal'. In general, `White Wedgewood' provided more consistent production than `Ideal' in both production seasons. An economic analysis in this study concludes that a grower is unlikely to make money growing dutch iris in a tobacco transplant greenhouse using these production systems unless there is a targeted local market.
Environmental Effects on the Performance of Foliar Applied Plant Growth Regulators: A Review Focusing on Tree Fruits
Authors: Stover E.W. , Greene D.W.
Published: December 2018

Plant response to foliar application of plant growth regulators (PGRs) is often variable, in part due to environmental factors. Weather prior to application is thought to influence cuticle development and thus PGR uptake. For example, in growth chamber studies foliar uptake of 1-naphthaleneacetic acid (NAA) is sometimes increased when fruit trees are placed in low temperature and high humidity several weeks prior to application. Environmental conditions over an extended period of time after application may influence PGR conversion to active form (e.g., ethephon), PGR metabolism, or metabolic factors that affect PGR activity in the plant. The effects of environmental conditions on PGR uptake have been investigated extensively in laboratory studies. In many cases, uptake is clearly increased by high temperatures immediately after application. Laboratory studies report a linear positive correlation between temperature and uptake and greater temperature response above 25 °C (77.0 °F). High humidity and longer drying time often are also reported to increase PGR uptake in laboratory studies. These results are consistent with many grower observations on effects of weather on chemical thinning and have been incorporated into many product labels and extension recommendations. However, relatively few field experiments have been reported in which the relationship between PGR response and environmental conditions were assessed. Wash-off studies have demonstrated that rain shortly after application may reduce efficacy of NAA. Several studies demonstrate environmental interaction with metabolic activity involved in PGR action. For example, shading after thinner application is reported to increase fruitlet abscission and enhance effectiveness of some thinning agents. Chemical thinning of apples (Malus ×domestica) with ethephon is reported to correlate strongly with temperature in the days after application, while studies suggest that higher temperatures after aminoethoxyvinylglycine (AVG) application may reduce control of preharvest drop. However, the stage of fruitlet development at apple thinning often appears to be more important than environmental conditions at the time of PGR application. In addition, field experiments indicate that longer drying times at lower temperatures seem to largely compensate for greater uptake rates at higher temperatures. This paper discusses data from published and previously unpublished experiments in order to understand the effects of environment on PGR response variability.
Effects of Grape Berry Moth Management Practices and Landscape on Arthropod Diversity in Grape Vineyards in the Southern United States
Authors: Williamson Joe R. , Johnson Donn T.
Published: December 2018

Agricultural monocultures with intensive pest management practices reduce diversity and create instability in agricultural ecosystems, thereby increasing reliance upon pesticides. This study compares the influence of three insect pest management programs in vineyards on arthropod diversity as well as parasitism and control of grape berry moth (Endopiza viteana), the key pest of grapes (Vitis labrusca) in eastern North America. Vineyards in Bald Knob, Hindsville, Judsonia, Lowell, and Searcy, Ark., were managed with a range of intensity of insecticide use, a reduced insecticide program with Exosex-GBM dispensers for mating disruption, or no pesticide use in abandoned vineyards. Arthropod diversity and carabid (Carabidae) density in each vineyard was sampled with pitfall traps. Grape berry moth flight was monitored by pheromone traps. Grape berry moth–infested grapes were collected from the field and reared in the lab until parasites or moths emerged. There were significant differences in arthropod diversity between vineyard sites, with Shannon diversity index values generally higher in woods and managed vineyards with conventional sprays and/or mating disruption than in abandoned sites. Shannon index values for arthropod diversity were significantly lower at the vineyard edge in Searcy (recently abandoned), vineyard center and edge in Bald Knob (abandoned), and the vineyard edge in Hindsville (conventional sprays). In 2003, carabid density was significantly highest in the edge and center of the Hindsville vineyard (high insecticide usage) and the abandoned Bald Knob vineyard had significantly lowest carabid density. Apparently, insecticide sprays resulted in more food on the vineyard floor for carabids. The vineyard floor management was too variable among vineyards to deduce its effect on carabid density. With some exceptions, low-spray and no-spray vineyards generally showed greater diversity and parasitism of grape berry moth than high-spray vineyards. Parasitism was higher in some high-spray vineyards than in low-spray with mating disruption vineyards. Grape berry moth flight and berry damage were more dependent on spray timing than intensity. This study demonstrates that insect pest management programs impact arthropod diversity and parasitism. Further testing is needed to determine why parasitism of grape berry moth decreased in the vineyards using the mating disruption tactic.
Yield, Quality, and Nutraceutical Potential of Selected Muscadine Cultivars Grown in Southwestern Arkansas
Authors: Striegler R.K. , Morris J.R. , Carter P.M. , Clark J.R. , Threlfall R.T. , Howard L.R.
Published: December 2018

A muscadine grape (Vitis rotundifolia) planting was established in 1996 at the Southwest Research and Extension Center in Hope, Ark., to provide information on the performance of muscadine grape cultivars in a region where cold hardiness is not a major limitation. This research evaluated harvest parameters, fruit and juice quality, and nutraceutical potential of selected muscadine cultivars grown in southwestern Arkansas. The cultivars evaluated were `Black Beauty', `Carlos', `Cowart', `Doreen', `Early Fry', `Fry', `Granny Val', `Ison', `Jumbo', `Late Fry', NC67A015-17, NC67A015-26, `Nesbitt', `Scarlett', `Southern Home', `Sterling', `Sugargate', `Summit', `Supreme', and `Tara'. Muscadine cultivars differed in productivity and fruit quality. In 2002 and 2003, juice was produced from `Carlos', `Granny Val', `Ison', `Nesbitt', `Southern Home', `Summit', and `Supreme' grapes. `Black Beauty' was also produced into juice in 2003. In 2002, `Nesbitt' grapes had the highest juice yield, 520 L·t–1 (124.6 gal/ton). `Ison' and `Supreme' juice had the highest soluble solids level. In 2003, `Granny Val' grapes had the highest juice yield, 551 L·t –1 (132.0 gal/ton). `Southern Home' juice had the highest soluble solids. The press materials of muscadine grapes were a potential source of high levels of nutraceutical compounds. Dried seeds had the highest total phenolic and oxygen radical absorbance capacity (ORAC) levels followed by the dried skins, the grapes, and then the juice. The skins of the black cultivars had the highest total anthocyanins level. `Supreme' seeds had the highest total phenolic and ORAC levels while `Ison' skins had the highest total anthocyanin levels. Based on yield, harvest, and juice quality, cultivars recommended to growers in southwestern Arkansas and other areas with a similar climate include `Black Beauty', `Carlos', `Fry', `Granny Val', `Nesbitt', `Southern Home', `Summit', and `Supreme'.
Diurnal Variation in Thigmotropic Inhibition of Stem Elongation
Authors: Van Gaal Tami , Erwin John E.
Published: December 2018

Wind, touching, and/or mechanical stress can restrict stem elongation. Removal of the registration of the growth retardant daminozide for use on edible crops increased interest in thigmotropic inhibition of stem elongation to control plant height in greenhouse crops, as well as a general desire by growers to decrease chemical inputs for floriculture crops. Since stem elongation varies diurnally, the question arises as to whether wind inhibition of stem elongation varies over a 24-hour period. Tomato (Lycopersicon esculentum) `MoneyMaker' and cosmos (Cosmos bipinnatus) `Imperial Pink' seedlings were placed under each of 10 wind perturbation treatments [applied for different durations and at different times during a 24-hour period; wind speed (perpendicular to the media) at seedling level was 30 km·h–1 (18.6 mph)] for 30 days. Data were collected on plant height and leaf number on days 1 and 30. The effect of wind on stem elongation differed with species; wind treatments restricted stem elongation more on cosmos than tomato (53% and 20%, respectively, across treatments). Tomato elongation was most restricted when seedlings received wind all day, all night, or all day and night. Within short-term treatments, internode length was least when tomato seedlings received a mid-day wind treatment. Cosmos elongation was most restricted when seedlings received a wind treatment all day or all night. Within short-term treatments, cosmos internode elongation was most restricted with early- and mid-day wind treatments. Data here suggest wind effects on elongation vary diurnally. In addition, the magnitude of wind effects on elongation varied with species and was greatest during the beginning of the day on cosmos, which mirrors when stem elongation is most sensitive to temperature fluctuations.
Establishing Tissue-cultured Sweetgum Plants in Soil
Authors: Tisserat Brent
Published: December 2018

Methods to enhance sweetgum (Liquidambar styraciflua L.) in vitro axillary shoot formation and shoot establishment into soil are presented. Sweetgum shoots grown in an automated plant culture system (APCS) produced 400 to 500 shoots via axillary branching compared to only 40 shoots produced within Magenta vessels containing agar medium after 8 weeks of incubation. Vitrification was observed in as many as 80% of the axillary shoots produced in the APCS. A continuous carbon dioxide (CO2)-flow-through system was tested on both vitrified and non-vitrified sweetgum shoots transferred from the APCS to soil. One- and two-cm-long vitrified shoots were grown within CO2-flow-through system chambers and subjected to 350, 1500, 3000, 10,000, or 30,000 μL·L–1 (ppm) CO2 for 4 weeks. Administering 10,000 μL·L–1 CO2 improved culture survival and enhanced overall shoot and root growth compared to shoots grown under ambient atmosphere (i.e., 350 μL·L–1 CO2).
Identification of Woody Plants with Implanted Microchips
Authors: Bowman Kim D.
Published: December 2018

Secure identification of individual plants by some kind of labels in the field is an important part of many types of horticultural, plant science, and ecological research. This report describes implanted microchips as one method of plant tagging that is reliable, durable, and secure. This technology may be especially useful in long-term experiments involving perennial woody plants. Two methods are described for implanting microchips in citrus trees that would also be applicable to other woody plant species. One method of implanting microchips is demonstrated to have no deleterious effect on citrus tree growth through the first 18 months after implantation into the tree. Since microchips implanted beneath the bark will become more deeply embedded in wood as the plants grow, signal penetration through wood was evaluated and determined to be sufficient for long-term field utility. Implanted microchips are potentially useful for secure tagging of valuable or endangered plant species to deter theft by providing secure and conclusive identification.
Integrating a University and Community College Course in Landscape Construction
Authors: St. Hilaire Rolston , Thompson James M.
Published: December 2018

Strong linkages among 2-year community colleges and 4-year universities are likely to foster the transition of more students into higher education and enhance student diversity. Two New Mexico educational institutions, Doña Ana Branch Community College (a 2-year community college) and New Mexico State University (a 4-year university), offered a landscape construction class as a joint course offering for students at both institutions. The objective of this educational approach was to develop a system that facilitates the seamless integration of compatible curricula from a community college and a university. Course evaluations showed that 63% of students enrolled in the combined class rated the combining of a university and community college class as an above average or excellent model of education. When asked to rate whether classroom materials and laboratory activities supported learning, 94% of the class rated those materials as excellent. Eighty-eight percent of students rated the presentation of subject matter as above average or excellent when asked if the subject matter was presented in an interesting manner. Students valued the experiential learning projects and would highly recommend the course to their peers. In this redesigned course, women and minorities constituted 63% of the class, suggesting that this educational approach has the potential to retain a large number of underrepresented groups in landscape horticulture. We conclude that this collaborative approach for teaching landscape horticulture is likely to enhance horticultural education and foster a seamless educational experience for students who transition from a community college to a university. Also, this educational approach could serve as a model for curricula that combine practical knowledge with advances in science and technology.
Growing Minds: The Effects of a One-year School Garden Program on Six Constructs of Life Skills of Elementary School Children
Authors: Robinson Carolyn W. , Zajicek Jayne M.
Published: December 2018

The goal of this study was to assess changes in the life skill development of elementary school students participating in a 1-year school garden program. The Life Skills Inventory included statements for six constructs of life skills including teamwork, self-understanding, leadership, decision making skills, communication skills, and volunteerism. The students were divided into two treatment groups, an experimental group that participated in the garden program and a control group that did not participate in the school garden program. Students in the control group had significantly higher overall life skills scores on the pretest compared to students participating in the garden program but the scores were no longer significantly different between the groups on the posttest scores at the end of the program. In addition, there were no significant differences in the control group's pretest scores compared to their posttest scores. However, the students in the experimental group did significantly increase their overall life skills scores by 1.5 points after participating in the garden program. Two internal life skill scales were positively influenced by the garden program; “working with groups” and “self understanding.”
A Comparison of a Gardening and Nutrition Program with a Standard Nutrition Program in an Out-of-school Setting
Authors: Poston Suzanne A. , Shoemaker Candice A. , Dzewaltowski David A.
Published: December 2018

After-school time is currently underutilized as a potential setting to promote healthy eating in children. Two programs, a standard nutrition program titled Professor Popcorn (PP) and a gardening and nutrition program using lessons from Junior Master Gardener: Health and Nutrition from the Garden (JMG), were compared to investigate their influence on nutrition knowledge, improving fruit and vegetable preference, and improving self-efficacy in gardening and eating fruit and vegetables in an out-of-school setting. Third through fifth graders participated in an after summer-school program (n = 11 in PP; n = 7 in JMG), and fourth graders participated in JMG (n = 11) during the fall after school. Knowledge, preference, and self-efficacy measures were obtained at the beginning and end of the program. Neither program improved nutrition knowledge, nor were there any differences between the PP and JMG mean difference scores. The programs did not improve fruit and vegetable preference or fruit and vegetable consumption self-efficacy. There was, however, a change in gardening self-efficacy for the summer JMG group compared with that of the fall JMG group. Gardening self-efficacy of the summer JMG group increased (P < 0.10), whereas that of the fall JMG group decreased (P < 0.05). Further investigations should examine the activities of gardening occurring at different times throughout the growing season, and the role that seasons have on the outcomes due to a garden-enhanced nutrition program. In addition, researchers should examine the amount of classroom time vs. gardening time that is needed to make a garden-enhanced nutrition program more effective in an out-of-school learning setting.
Plastics: Modifying the Microclimate for the Production of Vegetable Crops
Authors: Lamont William James
Published: December 2018

For centuries horticulturists have attempted to modify the environment in which vegetable crops are grown. A wide variety of techniques, such as glass cloches, hotcaps, cold frames, hotbeds, and various types of glass greenhouses, have been used to extend the production season. The discovery and development of the polyethylene polymer in the late 1930s, and its subsequent introduction in the early 1950s in the form of plastic films, mulches, and drip-irrigation tubing and tape, revolutionized the commercial production of selected vegetable crops and gave rise to a system of production known as plasticulture. Simply defined, plasticulture is a system of growing vegetable crops where significant benefit is derived from using products derived from polyethylene (plastic) polymers. The later discovery of other polymers, such as polyvinyl chloride, polypropylene, and polyesters, and their use in microirrigation systems, pipes, fertigation equipment, filters, fittings and connectors, containers for growing transplants, picking and packaging containers, and row covers further extended the use of plastic components in this production system. The complete plasticulture system consists of plastic and non-plastic components: plastic mulches, drip-irrigation, fertigation/chemigation, soil sanitation (fumigation and solarization), windbreaks, stand establishment technology, season-extension technology, integrated pest management, cropping strategies, and postharvest handling and marketing. In the plasticulture system, plastic-covered greenhouses, plastic mulches, row covers, high tunnels, and windbreaks both permanent and annual are the major contributors to modifying the cropping environment of vegetable crops, thus enhancing crop growth, yield, and quality. In addition to modifying the soil and air temperatures, there are also the benefits of protection from the wind and in some instances rain, insects, diseases, and vertebrate pests.
Management of Irrigation for Vegetables: Past, Present, and Future
Authors: Locascio Salvadore J.
Published: December 2018

Vegetables are grown throughout the U.S. on various soil types and in various climates. Irrigation is essential to supplement rainfall in all areas to minimize plant water stress. In the U.S., irrigated vegetable production accounts for about 1.9 million ha or 7.5% of the irrigated area. California, Florida, Idaho, Washington, Texas, Nebraska, Oregon, Wisconsin, and Arizona account for 80% of the U.S. production of irrigated vegetables. In the U.S., surface and subsurface (seepage) irrigation systems were used initially and are currently used on 45% of all irrigated crops with a water use efficiency of 33%. Sprinkler or overhead irrigation systems were developed in the 1940s and are currently used extensively throughout the vegetable industry. Sprinkler systems are used on 50% of the irrigated crop land and have a water use efficiency of 75%. In the late 1960s, microirrigation (drip or trickle) systems were developed and have slowly replaced many of the sprinkler and some of the seepage systems. Microirrigation is currently used on 5% of irrigated crops. This highly efficient water system (90% to 95%) is widely used on high value vegetables, particularly polyethylene-mulched tomato (Lycopersicon esculentum), pepper (Capsicum annuum), eggplant (Solanum melongena), strawberry (Fragaria ×ananassa), and cucurbits. Some advantages of drip irrigation over sprinkler include reduced water use, ability to apply fertilizer with the irrigation, precise water distribution, reduced foliar diseases, and the ability to electronically schedule irrigation on large areas with relatively smaller pumps. Drip systems also can be used as subsurface drip systems placed at a depth of 60 to 90 cm. These systems are managed to control the water table, similar to that accomplished with subsurface irrigation systems, but with much greater water use efficiency. Future irrigation concerns include continued availability of water for agriculture, management of nutrients to minimize leaching, and continued development of cultural practices that maximize crop production and water use efficiency.
Technical Advances and Strategies for Future Developments in Mechanization
Authors: Glancey James L. , Kee Edwin , Wootten Tracy
Published: December 2018

The vegetable industry is important to our nation as a provider of nutritious and safe food directly consumed by our citizens. It is also critical to a rich and vigorous national agriculture. During the 20th century, engineering innovations coupled with advances in genetics, crop science, and plant protection have allowed the vegetable industry in the U.S. to plant and harvest significantly more land with higher yields while using less labor. Currently, fresh and processed vegetables generate 16% of all U.S. crop income, but from only 2% of the harvested cropland. Yet, many of the challenges in production that existed a century ago still exist for many crops. Perhaps the most significant challenge confronting the industry is labor, often accounting for 50% of all production costs. A case study of the mechanized production system developed for processed tomatoes (Lycopersicon esculentum) confirms that systematic methodology in which the machines, cultural practices, and cultivars are designed together must be adopted to improve the efficiency of current mechanized systems as well as provide profitable alternatives for crops currently hand-harvested. Only with this approach will horticultural crop production remain competitive and economically viable in the U.S.
History and Perspectives on the Use of Disease Resistance Inducers in Horticultural Crops
Authors: da Rocha Andrea B. , Hammerschmidt Ray
Published: December 2018

A major challenge facing horticultural crop production is the need to provide field and postharvest disease control measures that help maintain high quality plant products. Producers and consumers also expect high quality produce with minimal or no pesticide residues and competitive prices. The chemical management of disease is further complicated by the development of fungicide resistance in many important pathogens. Because of these concerns, an alternative or complementary approach is the use of disease resistance inducers that activate the natural defenses of the plant. Induced disease resistance in plants has been studied in many different pathosystems for nearly a century. Resistance to plant disease can be induced systemically by prior infection with pathogens, by certain non-pathogenic microbes that colonize the surface of roots and leaves, or by chemicals. The application of resistance inducers should protect plants through the induction of defenses that are effective against a broad spectrum of pathogens. Over the last few years, a number of materials that could potentially be used as inducers of resistance in horticultural crops have been identified. Some of these materials are already commercially available. Although induced resistance is known to provide a broad spectrum of disease suppression, it may not be a complete solution because variation in the efficacy of disease resistance induction has been observed. The variation in the response may be dependent on the plant species and even cultivars, as well as variability in the spectrum of pathogens that resistance can be induced against. Induction of resistance depends on the activation of biochemical processes that are triggered in the plant, and therefore a lag time between treatment and expression of resistance occurs. This lag effect may limit the practical application of disease resistance inducers. Since the efficacy of the inducers also depends on the part of the plant that was treated, the product delivery (i.e., how the inducers would be applied in order to optimize their action) is another factor to be considered. Some studies have shown that there may be side effects on growth or yield characteristics when certain inducers are used. Understanding the biochemical interactions occurring between plants, pathogens and the inducers will provide information that may be useful for the optimization of this new approach on disease control. Approaches to integrate induced resistance with other management practices need to be investigated as a means to aid the development of sustainable disease management programs that are effective as well as economically and environmentally sound.
Paclobutrazol and Uniconazole Solutions Maintain Efficacy after Multiple Lily Bulb Dip Events
Authors: Ranwala N.K. Damayanthi , Ranwala Anil P. , Miller William B.
Published: December 2018

One of the problems associated with preplant bulb dips into plant growth regulator (PGR) solutions is the lack of knowledge of solution efficacy as an increasing number of bulbs are treated. We evaluated the effectiveness (“longevity”) of paclobutrazol (Bonzi) and uniconazole (Sumagic) solutions repeatedly used to dip hybrid lily (Lilium sp.) bulbs. Experiments were conducted over a 2-year period, using sequential 1-minute dips into paclobutrazol (100 or 200 mg·L–1) or uniconazole (2.5 mg·L–1). No difference in plant height occurred as the number of bulbs dipped into PGR solutions increased to at least 55 bulbs per liter. This was true whether bulbs were washed (with tap water to remove soil particles attached to the bulbs) or unwashed prior to the PGR dip. These findings have an important impact on cost effectiveness of bulb dips, as the more times the solution can be used, the lower the cost. Washed bulbs were taller than unwashed bulbs due to lower PGR liquid uptake in washed bulbs (about 1 mL less per bulb) compared to the unwashed bulbs. These results indicate that the hydration condition of bulbs prior to dipping can affect the amount of PGR liquid uptake and therefore final plant height.
Container Size and Planting Zone Influence on Transplant Survival and Growth of Two Coastal Plants
Authors: Thetford Mack , Miller Debbie , Smith Kathryn , Schneider Mica
Published: December 2018

Survival and subsequent growth of two beach species produced in containers of differing volume and depth were evaluated following transplant on Eglin Air Force Base, Santa Rosa Island, Fla. Rooted cuttings of gulf bluestem (Schizachyrium maritimum) were produced in four container types: 1-gal (gallon), 0.75-gal treepot, 1-qt (quart), or 164-mL Ray leach tube (RLT) containers. Root and shoot biomass of gulf bluestem harvested after 12 weeks in container production were greatest for plants grown in treepot containers and root: shoot ratio decreased as container size increased. Regardless of container size, survival of beach-planted gulf bluestem was 100%. Basal area of plants from standard gallon and treepot containers was similar 11 months after transplant and basal area for plants from treepot containers remained greater than plants from quart or RLT containers. Effect of planting zone [92, 124, 170, and 200 m landward of the Gulf of Mexico (Gulf)] on transplant survival was also evaluated for inkberry (Ilex glabra). Seedling liners of inkberry were produced in 3-gal treepot or gallon containers. Inkberry was taller when grown in 3-gal treepot containers than when grown in gallon containers. Regardless of container size, all inkberry planted 92 m from the Gulf died. Inkberry survival (>75%) when grown in 3-gal treepot containers was two to six times greater than plants grown in gallon containers (15%, 50%, 40%; 124, 170, and 200 m from Gulf, respectively). After 15 months, inkberry grown in 3-gal treepot containers remained larger with 1.5 times the mean maximum height and twice the mean canopy area compared to those grown in gallon containers.