bluuebunny/crossref_metadata_2025 huggingface dataset:
Decision Tool for Growers to Evaluate Economic Impact of Grafting Technology Adoption: An Application to Open-field Conventional Tomato Production
Authors: Rysin Olya , Louws Frank J.
Published: December 2018

Grafting could potentially become an important part of integrated pest management programs in vegetable crops in the United States due to increased pathogen densities, reliance on pathogen susceptible varieties, increased use of organic and high tunnel production systems, limited land or input resources, value-added benefits, and the loss of, or regulatory restrictions on, soil fumigants. Adoption of this technology imposes additional costs on growers due to significantly higher grafted transplant prices, but associated yield improvements are potentially more than sufficient to offset the higher transplant costs. Therefore, the economic impact of the technology adoption depends highly on the specific circumstances of each grower. In this study, we propose a decision tool for growers to facilitate grafting technology adoption. We demonstrate an application of the proposed tool to a scenario based on real-life data for the open-field production of tomato (Solanum lycopersicum). The results show that based on a 30% loss in marketable yields due to disease pressure in nongrafted systems, yield improvements in the grafted system with resistant rootstock were sufficient to offset higher transplant and harvesting costs and resulted in higher net revenues. Net revenue estimates were $7126/acre in the nongrafted system and $8374/acre in the grafted system. The sensitivity analysis resulted in positive net revenues in the grafted system ranging from $108 to $12,328 per acre. Estimated marketable yield required in the grafted system to breakeven with the nongrafted system was 73,880 or 19,980 lb/acre more than marketable yield in the nongrafted system.
Performance of High Tunnel Tomato Cultivars in Northern New England
Authors: Warren Nicholas D. , Sideman Rebecca G. , Smith Richard G.
Published: December 2018

Tomato (Solanum lycopersicum) growers select cultivars based on a range of performance criteria. Currently, however, information regarding tomato cultivar performance in high tunnels is lacking. We conducted a tomato cultivar trial in an 1800-ft2 plastic-covered high tunnel in Durham, NH, with 15 indeterminate cultivars using organic fertilizers and pesticides. Tomatoes were grown in-ground in a randomized complete block design (n = 4) using raised beds with plastic mulch and drip irrigation. Marketable and unmarketable yield, several yield components, and susceptibility to two common diseases, leaf mold (Fulvia fulva) and powdery mildew (Oidium lycopersici or Leveillula taurica), were evaluated over a 3-year period. Differences between cultivars existed in all areas of interest, and year-to-year variation in performance was noteworthy in this experiment. ‘Geronimo’ consistently had among the highest yields, ‘Arbason’ and ‘Massada’ produced many individual fruit, and several cultivars including Rebelski, Massada, and Geronimo showed no signs of disease. Some cultivars such as Conestoga appeared susceptible to several different physiological disorders while others were relatively robust against this type of marketable yield reduction. Because we assessed multiple yield and quality variables and observed apparent trade-offs in several of these, we used radar plots to summarize and communicate the performance of each cultivar in an intuitive and comparable manner. Based on these data, several tomato cultivars appear particularly well suited for high tunnel production in northern New England.
Use of Alternative Containers for Long- and Short-term Greenhouse Crop Production
Authors: Conneway Renee , Verlinden Sven , Koeser Andrew K. , Evans Michael , Schnelle Rebecca , Anderson Victoria , Stewart J. Ryan
Published: December 2018

While research on the use of alternative containers for greenhouse production is growing, most studies have focused on a limited number of types of alternative containers and primarily on short-term greenhouse crops. With the recent release of several new bioplastic alternatives, comparisons to established alternative containers and production of longer rotation ornamental crops should be investigated. Our work, therefore, investigates the performance of ten commercially available alternative containers and their effects on both a short-term ‘Sunpatiens Compacta’ impatiens (Impatiens ×hybrida) and a long-term greenhouse crop ‘Elegans Ice’ lavender (Lavendula angustifolia) at four different locations. Results indicated that plant growth in terms of dry weight differed by container at most locations. Combined analysis of all locations showed that only straw and a bioplastic sleeve outperformed plastic pots in terms of shoot dry weight and then only after 12 weeks of production. Leachate pH, but not electrical conductivity (EC), varied by container in both the short- and long-term crop with alternative containers made from composted cow manure and peat showing consistently higher and lower pH readings, respectively. Postharvest container strength varied significantly by container, with the plastic control maintaining the highest puncture resistance after both 6 and 12 weeks, in some instances matched by the puncture strength of coconut fiber pots. Some alternative containers, in particular, wood, manure, and peat showed algal growth after 6 and 12 weeks of greenhouse production. We conclude that while some alternative containers were linked to increased growth, most showed growth equal to the plastic control, and could therefore make appropriate alternatives to plastic pots. However, changes in pH, low puncture strengths after production, higher denesting times, and algal growth on manure, wood, and peat may make these pots less desirable alternatives than other pots under investigation. However, other factors not studied here, such as compostability, biodegradability in the landscape, water use, consumer preference, aesthetics, compatibility with mechanized operations, and cost may also need to be taken into account when deciding on an appropriate container for greenhouse production.
Multistate Evaluation of Plant Growth and Water Use in Plastic and Alternative Nursery Containers
Authors: Wang Xueni , Fernandez R. Thomas , Cregg Bert M. , Auras Rafael , Fulcher Amy , Cochran Diana R. , Niu Genhua , Sun Youping , Bi Guihong , Nambuthiri Susmitha , Geneve Robert L.
Published: December 2018

Containers made from natural fiber and recycled plastic are marketed as sustainable substitutes for traditional plastic containers in the nursery industry. However, growers’ acceptance of alternative containers is limited by the lack of information on how alternative containers impact plant growth and water use (WU). We conducted experiments in Michigan, Kentucky, Tennessee, Mississippi, and Texas to test plant growth and WU in five different alternative containers under nursery condition. In 2011, ‘Roemertwo’ wintercreeper (Euonymus fortunei) were planted in three types of #1 (≈1 gal) containers 1) black plastic (plastic), 2) wood pulp (WP), and 3) recycled paper (KF). In 2012, ‘Green Velvet’ boxwood (Buxus sempervirens × B. microphylla siebold var. koreana) was evaluated in 1) plastic, 2) WP, 3) fabric (FB), and 4) keratin (KT). In 2013, ‘Dark Knight’ bluebeard (Caryopteris ×clandonensis) was evaluated in 1) plastic, 2) WP, and 3) coir fiber (Coir). Plants grown in alternative containers generally had similar plant growth as plastic containers. ‘Roemertwo’ wintercreeper had high mortality while overwintering in alternative containers with no irrigation. Results from different states generally show plants grown in fiber containers such as WP, FB, and Coir used more water than those in plastic containers. Water use efficiency of plants grown in alternative containers vs. plastic containers depended on plant variety, container type, and climate.
Substrate Temperature in Plastic and Alternative Nursery Containers
Authors: Nambuthiri Susmitha , Geneve Robert L. , Sun Youping , Wang Xueni , Fernandez R. Thomas , Niu Genhua , Bi Guihong , Fulcher Amy
Published: December 2018

The green industry has identified the use of biodegradable containers as an alternative to plastic containers as a way to improve the sustainability of current production systems. Field trials were conducted to evaluate the performance of four types of 1-gal nursery biocontainers [keratin (KR), wood pulp (WP), fabric (FB), and coir fiber (Coir)] in comparison with standard black plastic (Plastic) containers on substrate temperature, water use, and biomass production in aboveground nurseries. Locations in Kentucky, Michigan, Mississippi, and Texas were selected to conduct experiments during May to Oct. 2012 using ‘Green Velvet’ boxwood (Buxus sempervirens × B. microphylla) and ‘Dark Knight’ bluebeard (Caryopteris ×clandonensis) in 2013. In this article, we were focusing on the impact of alternative container materials on hourly substrate temperature variations and plant growth. Substrate temperature was on an average higher (about 6 °C) in Plastic containers (about 36 °C) compared with that in WP, FB, and Coir containers. However, substrate temperature in KR containers was similar to Plastic. Substrate temperature was also influenced by local weather conditions with the highest substrate temperatures recorded in Texas followed by Kentucky, Mississippi, and Michigan. Laboratory and controlled environment trials using test containers were conducted in Kentucky to evaluate sidewall porosity and evaporation loss to confirm field observations. Substrate temperature was similar under laboratory simulation compared with field studies with the highest substrate temperature observed in Plastic and KR, intermediate in WP and lowest in FB and Coir. Side wall temperature was higher in Plastic, KR, and FB compared with WP and Coir, while side wall water loss was greatest in FB, intermediate in WP and Coir, and lowest in plastic and KR. These observations suggest that the contribution of sidewall water loss to overall container evapotranspiration has a major influence on reducing substrate temperature. The porous nature of some of the alternative containers increased water use, but reduced heat stress and enhanced plant survival under hot summer conditions. The greater drying rate of alterative containers especially in hot and dry locations could demand increased irrigation volume, more frequent irrigation, or both, which could adversely affect the economic and environmental sustainability of alternative containers.
Feasibility of Using Biocontainers in a Pot-in-pot System for Nursery Production of River Birch
Authors: Li Tongyin , Bi Guihong , Niu Genhua , Nambuthiri Susmitha S. , Geneve Robert L. , Wang Xueni , Fernandez R. Thomas , Sun Youping , Zhao Xiaojie
Published: December 2018

The performance of biocontainers as sustainable alternatives to the traditional petroleum-based plastic containers has been researched in recent years due to increasing environmental concern generated by widespread plastic disposal from green industry. However, research has been mainly focused on using biocontainers in short-term greenhouse production of bedding plants, with limited research investigating the use of biocontainers in long-term nursery production of woody crops. This project investigated the feasibility of using biocontainers in a pot-in-pot (PIP) nursery production system. Two paper (also referred as wood pulp) biocontainers were evaluated in comparison with a plastic container in a PIP system for 2 years at four locations (Holt, MI; Lexington, KY; Crystal Springs, MS; El Paso, TX). One-year-old river birch (Betula nigra) liners were used in this study. Results showed that biocontainers stayed intact at the end of the first growing season, but were penetrated to different degrees after the second growing season depending on the vigor of root growth at a given location and pot type. Plants showed different growth rates at different locations. However, at a given location, there were no differences in plant growth index (PGI) or plant biomass among plants grown in different container types. Daily water use (DWU) was not influenced by container type. Results suggest that both biocontainers tested have the potential to be alternatives to plastic containers for short-term (1 year) birch production in the PIP system. However, they may not be suitable for long-term (more than 1 year) PIP production due to root penetration at the end of the second growing season.
Effects of Pinching, Number of Cuttings per Pot, and Plant Growth Regulators on Height Control of Purple Firespike
Authors: Rezazadeh Amir , Harkess Richard L.
Published: December 2018

Purple firespike (Odontonema callistachyum), native to Central America, has potential for use as a new flowering potted plant. The effects of number of pinches (zero, one, or two) and number of cuttings (one, two, or three) per 6-inch pot were evaluated on the control of plant height. Plant height was suppressed as the pinch number increased. The greatest reduction was recorded with one cutting per pot and two pinches. The maximum number of branches per pot was recorded with two pinches and three cuttings per pot. In a second experiment, plant growth regulators (PGR) were also tested for efficacy of height control; 2 weeks after pinching, foliar sprays of paclobutrazol, flurprimidol, daminozide, chlormequat, and a tank-mix of daminozide + chlormequat or media drenches of paclobutrazol, uniconazole, or flurprimidol were applied. Plant height, leaf area, and leaf dry weight were recorded at 3, 6, and 9 weeks after PGR application. Maximum height control was obtained with uniconazole drench at 8 ppm, resulting in plants 22 cm tall, 61% shorter than the untreated control (56 cm); however, it resulted in severe leaf distortion. Plant height was 56% and 46% shorter than the control using drenches of paclobutrazol at 30 ppm and flurprimidol at 15 ppm, respectively. Daminozide spray at 2000 ppm and tank-mix of daminozide + chlormequat at 4500/1500 ppm suppressed stem elongation by 20.3% and 19%, respectively. Plants treated with paclobutrazol drench at 30 ppm reduced leaf area and leaf dry weight compared with other PGRs. Chlormequat spray at tested concentrations was ineffective for controlling firespike plant growth. The most attractive potted plants were produced using a drench application of paclobutrazol at 10 or 15 ppm.
The Effect of Urban Tree Canopy Cover and Vegetation Levels on Incidence of Stress-related Illnesses in Humans in Metropolitan Statistical Areas of Texas
Authors: Tarar Ghazal , Etheredge Coleman L. , McFarland Amy , Snelgrove Amy , Waliczek Tina M. , Zajicek Jayne M.
Published: December 2018

One-third of Americans are reportedly living with extreme stress, with 75% to 90% of visits to primary care physicians being for stress-related problems. Past research found visiting green areas lowers blood pressure, reduces headache and fatigue, improves mood, and hastens recovery from stress. The main objective for this study was to determine if stress-related illness rates in regions of Texas were related to vegetation rates and tree canopy cover. Data on the stress-related illnesses of high blood pressure and heart attacks were collected from the Center for Health Statistics and the Texas Department of State Health Services for all 25 metropolitan statistical areas (MSAs) in Texas. MSAs are counties or group of counties with a central city or urbanized area of at least 50,000 people. Percent canopy cover was calculated for each MSA using the Multi-Resolution Land Characteristics National Land Cover Data canopy cover dataset. Vegetation rates for all the MSAs were examined and mapped for illustration using geographical information system (GIS) software. Visual relationships among the data were observed. Quantitative data were also analyzed. When mapping stress-related illness rate into MSA regions of Texas, no clear trend was observed with vegetation rates or percent tree canopy cover when compared with stress-related illness rates. Semipartial correlations were calculated to analyze the relationship between tree canopy cover and vegetation rate and stress-related illness rate variables after controlling the effect of external variables like income levels, age, population, and ethnicity. There was no significant positive or negative relationship found between stress-related illness data when compared with percent canopy and vegetation index for any the 25 MSAs of Texas.
Postharvest Ripening and Quality of Guatemalan-West Indian Avocado Hybrids under Simulated Commercial Shipping Temperatures Following Treatment with Aqueous 1-Methylcyclopropene
Authors: Berry Adrian D. , Sargent Steven A. , Pereira Marcio Eduardo Canto , Huber Donald J.
Published: December 2018

Two Guatemalan-West Indian avocado (Persea americana) hybrids (‘Monroe’ and ‘Booth 8’) were treated with an aqueous formulation of 1-methylcyclopropene (1-MCP) to determine effects on ripening and quality during storage simulating commercial shipping temperatures. Fruit harvested at preclimacteric stage were immersed in aqueous 1-MCP at 75 μg·L−1 (1.39 mmol·m−3) or in deionized water for 1 minute, stored at 10 °C for 14 days, and then transferred to 20 °C until ripe. Respiration rate, ethylene production, softening, and change in epidermal hue* angle were delayed and/or suppressed in both cultivars exposed to 1-MCP, although effects were less pronounced with Booth 8. Hue* angles for 1-MCP-treated ‘Monroe’ fruit had the highest values (darkest green peel color) of all treatments at full-ripe stage (hue* angle = 117). For control and treated ‘Monroe’ fruit respiration peaked on days 15 and 21, while ethylene production from both treatments peaked on day 16. Respiration and ethylene production peaked on day 16 for both control and 1-MCP–treated ‘Booth 8’ fruit. Fruit treated with 1-MCP consistently showed diminished respiration and ethylene peaks. Days to full-ripe stage were unaffected by treatment. ‘Booth 8’ fruit from both treatments were considered ripe (15 N whole fruit firmness) after 17 days; however, only 8% of control fruit were marketable, whereas 58% of 1-MCP-treated fruit were marketable, based on subjective appearance ratings using the Jenkins–Wehner score. The development of peel blemishes during storage was the primary cause of unmarketable fruit. ‘Monroe’ control and 1-MCP–treated fruit were soft after about 22 days and were significantly more marketable (control 70% and 1-MCP 85%). Avocados treated with 1-MCP ripened over a longer period than control fruit but maintained a higher percentage of marketable fruit.
Incorporating Early Spring Bulbs into Dormant Warm-season Turfgrasses
Authors: Richardson Michael D. , McCalla John , Buxton Tina , Lulli Filippo
Published: December 2018

Many early spring bulb species are naturally found in grassy areas such as meadows or lawns. However, few studies have been conducted to define this concept in maintained lawns, especially warm-season lawns such as zoysiagrass (Zoysia japonica) or bermudagrass (Cynodon dactylon). Four early spring bulb species, including two crocus species (Crocus tommasinianus ‘Ruby Giant’ and Crocus chrysanthus ‘Goldilocks’), reticulated iris (Iris reticulata ‘Cantab’), and snowdrop (Galanthus elwesii) were established in a zoysiagrass lawn site in Fall 2010. In Spring 2011 and 2012, five common preemergence herbicides used on lawns were applied across the plots to determine phytotoxicity. In addition, mowing treatments were started on plots at two timings (15 Mar. and 15 Apr.) to determine how mowing might affect survival and performance of the bulb species. Early performance was good for all bulb species and greater than 50% flower production was observed in the first spring (2011) after planting. However, in the subsequent 3 years (2012–14), the only species that persisted and continued to flower adequately each spring was ‘Ruby Giant’ crocus. Herbicides and mowing did not affect bulb survival or performance in the trial, suggesting that typical lawn management practices will not be deleterious to the bulbs. These results demonstrate that early spring bulbs may be incorporated into dormant, warm-season lawns, but species and cultivar selection will be crucial for long-term performance.
EduAPPLE: Interactive Teaching Tool for Apple Tree Crown Formation
Authors: Kohek Štefan , Guid Nikola , Tojnko Stanislav , Unuk Tatjana , Kolmanič Simon
Published: December 2018

In central Europe there are many backyard fruit growers who receive no proper education about fruit tree care. Their knowledge is mostly based on various handbooks and learning through trial and error. Such learning is slow and can even result in damage to the tree. To shorten the learning time, a new interactive teaching tool EduAPPLE has been developed based on the basic laws of apple tree (Malus ×domestica) growth and training. Pruning, weighting, tying, and spreading can be interactively practiced over and over again without any danger to the actual trees. Training responses are immediately seen and are analogous to those of real trees. They are not only predetermined by a set of rules, but also calculated based on the changes the actions cause to the light interception of the tree. EduAPPLE enables high-quality views of trees and their light interception from all angles in real time and is designed for education regarding free-standing apple tree training (spindle). It can, therefore, be used in schools, universities, and other educational organizations, as well as by tree growers, including the large number of growers having only a few fruit trees.
Response of Blackberry Cultivars to Fertilizer Source during Establishment in an Organic Fresh Market Production System
Authors: Fernandez-Salvador Javier , Strik Bernadine C. , Bryla David R.
Published: December 2018

Blackberry (Rubus ssp. Rubus) cultivars, three trailing types (Marion, Black Diamond, and Obsidian) and one semierect type (Triple Crown), were studied for their response to different types of fertilizer from 2011–12, at a certified organic, grower collaborator site located in Jefferson, OR. Plants were fertilized at a target rate of 50 lb/acre nitrogen (N) each spring using three different sources: 1) a liquid fish and molasses blend (4N–0P–1.7K); 2) pelletized soy (Glycine max) meal (8N–0.4P–1.7K); and 3) pelletized, processed poultry litter (4N–1.3P–2.5K). Plants were drip irrigated, and weeds were managed using a polypropylene, permeable landscape fabric (weed mat). Plant responses were greatly affected by cultivar, whereas the effects of fertilizer type were relatively minor. ‘Triple Crown’ produced the greatest yield in both years, whereas ‘Black Diamond’ and ‘Marion’ had the lowest yield in 2011 and 2012, respectively. ‘Triple Crown’ fruit had the highest percent soluble solids and were the least firm in 2011, whereas ‘Marion’ fruit were the least firm in 2012. Harvest date, within year, affected the fruit quality variables measured in all cultivars. Most soil nutrient levels were within the recommended range for all fertilizer treatments, except for boron (B), which declined to deficient levels in the second year. Fertilizer type had no effect on soil nutrient levels other than fertilization with the fish and molasses blend product increased soil potassium and sodium. Soil nutrient levels were affected by cultivar but varied by year for many nutrients. Primocane leaf tissue nutrient concentrations were above or within recommended standards for most nutrients, except for magnesium (Mg), calcium (Ca), and B, which, depending on the cultivar, were below standards. Over the 2-year study, the blackberry cultivars responded similarly to the three types of organic fertilizer. However, the cost of N varied from $8.16/lb for the liquid fish and molasses blend, $5.35/lb for the pelletized soy meal, and $2.54/lb for the pelletized, processed poultry litter. Supplemental fertilization with B, Mg, and Ca would be required with each fertilizer studied to maintain recommended soil fertility levels.
Foliar Application of Dikegulac Sodium Increases Branching of ‘Merritt’s Supreme’ Bigleaf Hydrangea
Authors: Sun Youping , Bi Guihong , Niu Genhua , Perez Christina
Published: December 2018

The goal of this experiment was to evaluate the efficiency of foliar application of dikegulac sodium on increasing the lateral branching of ‘Merritt’s Supreme’ bigleaf hydrangea (Hydrangea macrophylla). Plants were grown in greenhouses at two locations including El Paso, TX and Kosciusko, MS. Two weeks before application of dikegulac sodium, half of plants were hand-pinched leaving two nodes. Foliar spray of dikegulac sodium at 400, 800, or 1600 mg·L−1 was then applied to pinched and unpinched plants. There were two additional control treatments: pinched or unpinched without application of dikegulac sodium. Data were collected at 2 weeks, 6 weeks, 80 days, and 10 months after treatments. Bigleaf hydrangea plants exhibited severe phytotoxicity including interveinal chlorosis or bleaching of new growth at 2 weeks after application of dikegulac sodium with more pronounced symptoms at higher dikegulac sodium concentrations. The severity of phytotoxicity symptoms became less significant at 6 weeks after treatment. The effect of dikegulac sodium on bigleaf hydrangea plant growth, number of branches, and number of flowers depended on both locations and dosages. In El Paso, TX, dikegulac sodium at 800 or 1600 mg·L−1 inhibited bigleaf hydrangea plant growth at 6 weeks and 80 days after treatment, and this effect disappeared at 10 months after treatment. Dikegulac sodium at all tested dosages doubled or tripled the number of branches of pinched or unpinched bigleaf hydrangea, respectively, at 80 days after treatment. At 10 months after treatment, the number of branches and flowers of bigleaf hydrangea plants tended to increase, but was insignificant. In Kosciusko, MS, dikegulac sodium at 1600 mg·L−1 reduced the plant growth at 6 weeks after treatment. This treatment increased the number of branches and flowers of unpinched plants by 196% and 95% and pinched plants by 53% and 31%, respectively, at 10 months after treatment. Dikegulac sodium application could be used to increase number of branches and flowers and produce compact ‘Merritt’s Supreme’ bigleaf hydrangea. However, the efficacy varied with environmental conditions.
Increasing Plant Density in Eastern United States Broccoli Production Systems to Maximize Marketable Head Yields
Authors: Ward Brian , Smith Powell , James Susan , Stansell Zachary , Farnham Mark
Published: December 2018

Increased demand for fresh market crown-cut broccoli (Brassica oleracea var. italica) has led to increased production along the eastern seaboard of the United States. Maximizing broccoli yields is a primary concern for quickly expanding eastern markets. Thus, a plant density study was carried out in Fall 2012 and 2013 using the hybrid cultivar Emerald Crown on a commercial farm in Summerton, SC, and in Fall 2013 using ‘Emerald Crown’ and another hybrid, ‘Durapak 19’, on a research farm in Charleston, SC. The objective was to determine the effect of variable within-row spacings of 4, 6, and 8 inches (using a system with double rows spaced 12-inches apart) on marketable yields and quality in the three environments. Our results indicated that increasing plant density by reducing within-row spacing to 4 inches significantly increased overall yield per hectare over the 6- and 8-inch spacing treatments at two of three environments. Stem diameter and average head weight were unaffected by plant density; however, heads harvested from plots with the highest plant densities had significantly (P < 0.01) lower bead uniformity in the Summerton 2012 trial, and significantly (P < 0.05) larger bead size in the two trials conducted in 2013. In general, the highest total marketable yields were from the 4-inch within-row spacing, but increased competition at the highest density may increase the risk of plants producing heads with lower quality characteristics. With the increased risk of producing lower quality marketable heads along with the increased production costs associated with the 4-inch spacing, yield and head quality attributes may be optimized at the 6-inch within-row spacing.
Occurrence, Severity and Initiation of Internal Necrosis in ‘Covington’ Sweetpotato
Authors: Jiang Chen , Perkins-Veazie Penelope , Blankenship Sylvia M. , Boyette Michael D. , Pesic-VanEsbroeck Zvezdana , Jennings Katherine M. , Schultheis Jonathan R.
Published: December 2018

A series of studies were conducted to better understand the occurrence and causes of internal necrosis (IN) in ‘Covington’ sweetpotato (Ipomoea batatas). Assessment of the problem among the industry was done for 2 years and revealed that IN was widespread in commercial storage facilities throughout the state of North Carolina; both incidence and severity were generally low (<10% incidence with minimal severity of symptoms). A few storage rooms had a high percentage of IN with severe storage root symptoms but results were inconsistent across years and among rooms. Preharvest studies with commercially used insecticides did not induce IN, but the harvest aid ethephon consistently induced IN with an incidence higher than 50%. Internal necrosis symptoms were not detectable at harvest, and earliest consistent incidence was observed 6 days after harvest (DAH) during the curing phase. Symptoms became more prevalent and severe at 30 DAH. However, in commercial storage rooms, no relationship was found between IN incidence and postcuring storage temperature or relative humidity (RH) conditions. Sweetpotato storage roots stored in air-tight barrels and exposed to 100 ppm ethylene after curing showed no relationship between the presence of ethylene gas in storage and incidence of IN. Our results indicate that IN incidence of ‘Covington’ is erratic with no obvious cause among storage rooms and that initiation of IN may occur most frequently during the first week following harvest.
Ethephon with 1-Aminocyclopropane-1-Carboxylic Acid Can Defoliate Grapevines, and Thereby Improve Vine-drying of Grapes
Authors: Vieira da Costa Thiago , Filho João Alexio Scarpare , Fidelibus Matthew W.
Published: December 2018

In two experiments, various combinations of ethephon, with or without 1-aminocyclopropane carboxylic acid (ACC), were applied to the fruiting zone of ‘Selma Pete’ raisin grapes (Vitis vinifera) to determine whether any could serve as a defoliant, and if so, whether defoliation improved subsequent vine drying of the grapes. In the first experiment, the fruiting zone was treated on 8 Aug. 2013 with a control (water) and one of four plant growth regulator (PGR) treatments: 1000 ppm ethephon, 1000 ppm ethephon plus 1000 ppm ACC, 2000 ppm ethephon, and 2000 ppm ethephon plus 1000 ppm ACC. In the first experiment, treatment with any of the PGRs hastened leaf senescence, but leaf greenness, measured with a SPAD meter, declined most rapidly in leaves from vines treated with 2000 ppm ethephon or 2000 ppm ethephon plus 1000 ppm ACC, and defoliation was best in vines treated with 2000 ppm ethephon plus 1000 ppm ACC. None of the treatments in the first study affected berry composition, hastened berry drying, or ultimately affected raisin moisture or quality. In a second experiment, initiated 18 days later, a factorial design was employed to determine whether three chemical treatments, a control (water spray), 2000 ppm ethephon, and 2000 ppm ethephon plus 1000 ppm of ACC, might interact with fruiting zone orientation (east or west facing) to affect leaf senescence or berry drying. The second study confirmed that 2000 ppm ethephon and 2000 ppm ethephon plus 1000 ppm ACC induced rapid leaf senescence. Defoliation proceeded more rapidly in the second study and by 13 days after treatment, vines treated with 2000 ppm ethephon plus 1000 ppm ACC had less than one leaf layer remaining in the fruiting zone compared with more than 2.5 leaf layers in untreated vines. Treatments again had no effect on berry fresh weight or composition, but grapes on west-facing vines treated with 2000 ppm ethephon plus 1000 ppm ACC dried significantly better than grapes on vines subjected to other treatments, possibly because the higher temperatures of west-facing vines coupled with better defoliation of the 2000 ppm ethephon plus 1000 ppm ACC treatment was sufficient to improve grape drying compared with vines subjected to other trellis orientation and chemical treatment combinations. Therefore, we conclude that treatment with ethylene-promoting PGRs can defoliate the fruiting zone of ‘Selma Pete’ grapes with divided canopies, and such defoliation treatments may enhance berry drying when drying is initiated later than normal.
Evaluation of Epicotyl Grafting on 25- to 55-day-old Pecan Seedlings
Authors: Zhang Rui , Peng Fang-Ren , Le Dong-Liang , Liu Zhuang-Zhuang , He Hai-Yang , Liang You-Wang , Tan Peng-Peng , Hao Ming-Zhuo , Li Yong-Rong
Published: December 2018

Scion wood of ‘Caddo’ and ‘Desirable’ pecan (Carya illinoinensis) was grafted onto the epicotyl of 1-month-old, open-pollinated ‘Shaoxing’ pecan seedlings for evaluation as a grafting technique to reduce the time to produce grafted trees. The results showed that seedlings grafted with “base scions” had higher survival than those grafted with “terminal scions” for both ‘Caddo’ and ‘Desirable’. Also, grafting with paraffinic tape could achieve greater success rate than that with medical tape. The most ideal time to perform this grafting was late April in Nanjing, China, when pecan seedlings were about 35 days old. This study demonstrated that the technique yielded successful epicotyl grafting of >70%, and it could thus be applied in practice.
Performance of Sweetpotato Cultivars Grown Using Biodegradable Black Plastic Mulch in New Hampshire
Authors: Sideman Rebecca G.
Published: December 2018

We evaluated the performance of several sweetpotato (Ipomoea batatas) cultivars grown on raised beds covered with biodegradable black mulch in New Hampshire. Six cultivars were evaluated over 4 years, and an additional four cultivars were evaluated in 2 or 3 years. Cultivars showed significant differences in marketable yield, percent cull, and percent small roots. The cultivars Covington and B94-14 Beauregard consistently produced high yields, whereas Vardaman consistently produced the lowest yields. ‘Georgia Jet’ exhibited variable performance, with marketable yields among the highest in 1 year and the lowest in another, largely because of a high percentage of cull roots due to severe cracking. Yields measured in our study compare favorably with average U.S. yields, with several cultivars producing over 400 50-lb bushels/acre in all years in which they were grown. In a 2-year study with the cultivar Beauregard, biodegradable mulch increased overall yields (marketable, cull, and small roots) as compared with bare ground production on raised beds. However, the percentage of culled roots was higher in mulch treatments, primarily due to breakage during digging, and the observed increases in marketable yields were not statistically significant.
Nutrient Management Practices in Perennial Strawberry are Informed by Understanding the Relationships among Carbohydrate Status, Nitrogen Availability, and Soil Composition
Authors: Pritts Marvin P.
Published: December 2018

Strawberry (Fragaria ×ananassa) is a perennial plant with a compressed woody crown that responds to the environment in a similar way as other temperate fruit crops. Nutrient management practices are also similar, with a few exceptions. Levels of preplant amendments are determined based on soil test results, and are used to increase nutrient availability and modify pH as needed. Once plants are established, soil tests, coupled with foliar tissue analysis and observations of plant growth, are the best indicators of plant nutrient status and limitations. Drip irrigation is more efficient than granular applications for supplying soluble nutrients such as nitrogen (N). While most temperate fruit crops respond well to N in spring when growth resumes after winter, applications of spring N in strawberry can cause excessive vegetative growth, reduce fruit quality, and have only a marginal impact on yield. N is most efficiently taken up by plants when conditions favor root growth, and N applied in summer or fall is more effective at increasing yield the following spring, assuming that the carbohydrate status of the plant is good. However, if carbohydrate status is poor, supplemental N late in the season can reduce yield by requiring additional carbon (C) for N uptake. Many questions remain to better understand how to manage nutrients optimally in perennial strawberry.
The Case for a National Strategic Plan for Consumer Horticulture Research, Education, and Extension
Authors: Bauske Ellen M. , Bachman Gary R. , Bewick Tom , Bradley Lucy , Close David , Durham Rick , Meyer Mary Hockenberry
Published: December 2018

Consumer horticulture encompasses interior and exterior ornamental, food, and community gardening. These activities influence the environment in many ways, affecting water quality and quantity, waste management, wildlife, and environmental sustainability. Consumer horticulture also impacts human health and well-being. In spite of keen consumer interest and the robust commercial impact, there is a paucity of support for consumer horticulture at both the state and federal levels. To explore strategies for increasing support for consumer horticulture, a workshop with four presentations was held at the annual conference of the American Society for Horticultural Science on 31 July 2014 in Orlando, FL. Presentations described the formation of a new Southern Experiment Extension/Research Activity, Landscapes and Gardens for Better Living (SERA44); the local funding sources and local issues that focus research, education, and extension efforts in consumer horticulture; and the need to develop shared goals to drive regional projects. The need for a national strategic plan for consumer horticulture, and a process for creating one, was outlined. A strategic plan could galvanize the support of diverse stakeholders; focus research, education, and extension efforts; and build a strong case for resources dedicated to consumer horticulture.
Evaluating Strip Tillage and Rowcover Use in Organic and Conventional Muskmelon Production
Authors: Tillman Jennifer , Nair Ajay , Gleason Mark , Batzer Jean
Published: December 2018

Increasing interest in using cover crops and reduced tillage to build soil health has created a demand for strategies to implement rolled cover crop systems. In northern areas of the United States, cool soil temperature in rolled cover crop systems can create a challenge when growing warm season vegetable crops. The use of rowcovers could mitigate the issue and facilitate adoption of rolled cover crop systems for both conventional and organic growers. This study investigated muskmelon (Cucumis melo) in two production systems, strip tillage (ST) into rolled cereal rye (Secale cereale) or conventional tillage with black plastic mulch (plasticulture), with or without the use of spunbonded polypropylene rowcovers. The trial was conducted in two fields, one in organic management and the other in conventional management. In general, ST led to cooler, moister soils than plasticulture, but rowcovers rarely affected soil temperature. Rowcovers increased mean and maximum daily air temperature by up to 4.2 and 11.7 °C, respectively, and decreased average daily light intensity by 33% to 37%. Rowcovers sometimes increased fruit size, but rarely affected marketable yield. Overall, ST reduced marketable yield compared with plasticulture by 6732 to 9900 lb/acre; however, ST with rowcovers often produced similar vegetative growth compared with plasticulture without rowcovers. Given the slow vining growth habit of muskmelon and the late planting inherent in a rolled cereal rye system, achieving high muskmelon yields, especially early yields, may be difficult.
Response of Seashore Dropseed and Weed Species to the Preemergence Herbicide Oxadiazon Applied as a Component of a Hydromulch Cap
Authors: Lukas Scott B. , DeFrank Joseph , Baldos Orville C. , Sakamoto Glenn S.
Published: December 2018

In Hawaii, seashore dropseed (Sporobolus virginicus), a coastal native grass, has been identified as a useful species for roadside revegetation. Cuttings of seashore dropseed covered with a hydromulch cap, irrigated, and managed to control weeds have greater establishment success. In this study, the efficacy and phytotoxicity of the preemergence herbicide oxadiazon applied as a component of the hydromulch cap over seashore dropseed cut stems was evaluated. Oxadiazon in two formulations, granule and suspension concentrate (SC), was applied at two rates of 2.0 and 4.0 lb/acre, resulting in four chemical treatments. Seashore dropseed response was recorded as numerical counts of new shoots, aboveground biomass, and percent visual coverage. The highest new shoot counts of seashore dropseed, aboveground biomass, and visual canopy coverage were recorded in plots treated with the granular (G) formulation of oxadiazon applied at 2.0 lb/acre. All hydromulch cap treatments containing herbicides reduced weed pressure compared with the untreated control treatment. Granular oxadiazon at 2.0 lb/acre in the hydromulch cap provided commercially acceptable weed control while maintaining high levels of rooting and plant vigor during the establishment period.
Economic Viability and Environmental Impact Assessment of Three Different Strawberry Production Systems in the Southeastern United States
Authors: Rysin Olya , McWhirt Amanda , Fernandez Gina , Louws Frank J. , Schroeder-Moreno Michelle
Published: December 2018

In this study, we investigate the economic viability and environmental impact of three different soil management systems used for strawberry (Fragaria ×ananassa) production in the southeastern United States: 1) a conventional production system that is based on the current production practices implemented by growers, 2) a nonfumigated compost system with summer cover crop rotations and beneficial soil inoculants, and 3) an organic production system that includes practices approved for use under the National Organic Program (NOP). Under our assumptions, all three systems resulted in positive net returns estimated at $14,979, $11,100, and $19,394 per acre, respectively. The nonfumigated compost system and organic system also both resulted in considerable reductions in negative environmental and human health impacts measured by a set of selected indicators. For example, the total number of lethal doses (LD50) applied per acre from all chemicals used in each system and measuring acute human risk associated with each system declined from 118,000 doses/acre in the conventional system to 6649 doses/acre in the compost system and to 0 doses/acre in the organic system. Chronic human health risk, groundwater pollution risk, and fertilizer use declined as well in the compost and organic systems as compared with the conventional system.
Ethephon Foliar Sprays Prevent Premature Flowering of Tissue Culture-propagated Streptocarpus Hybrids
Authors: Currey Christopher J. , Flax Nicholas J.
Published: December 2018

Our objective was to quantify foliar ethephon application effects on flowering and growth of several streptocarpus (Streptocarpus ×hybridus) cultivars. ‘Ladyslippers Blue Halo’, ‘Ladyslippers Deep Blue Vein’, and ‘Ladyslippers Red Rose’ streptocarpus were planted in 6-inch containers filled with a soilless substrate. Foliar spray applications of solutions containing 0, 125, 250, 500, or 1000 mg·L−1 ethephon were applied either 2 weeks after planting (one application) or 2 and 4 weeks after planting (two applications). After 13 weeks, the total number of inflorescences was recorded and the growth index (GI) and time to flower were calculated. The efficacy of ethephon sprays depended on the concentration, number of applications, and cultivar. A single application of 250 to 1000 mg·L−1 ethephon delayed flowering of ‘Ladyslipper Deep Blue Vein’ by 9 to 27 days, whereas one application of 1000 mg·L−1 applied to ‘Ladyslipper Red Rose’ delayed flowering by 9 days. Similarly, two applications of any ethephon concentration delayed flowering of ‘Ladyslipper Deep Blue Vein’ by up to 37 days, while flowering of ‘Ladyslipper Red Rose’ was delayed by 17 days when 1000 mg·L−1 was applied. The GI of ‘Ladyslipper Deep Blue’ and ‘Ladyslipper Red Rose’ was unaffected by ethephon and, while the GI of ‘Ladyslipper Blue Halo’ was smaller than untreated plants when one or two applications of 500 or 1000 mg·L−1 ethephon was applied; these smaller plants were still of marketable size and quality. We conclude that ethephon may be used to delay flowering and reduce the number of inflorescences formed before finishing with minimal impact on finished plant size.
Effects of Different Culture Media on Growth and Proliferation of Dendrobium ‘Earsakul’ Protocorm-like Bodies
Authors: Tantasawat Piyada A. , Khairum Apinya , Arsakit Kitiya , Poolsawat Oythip , Pornbungkerd Paniti , Kativat Chitpan
Published: December 2018

The effects of culture media on growth and proliferation of ‘Earsakul’ dendrobium (Dendrobium) protocorm-like bodies (PLBs) were evaluated in a two-step culture. After culturing on each of the four first step media for 4 months and on each of the four second step media for 4 months, the greatest total PLB fresh weight, increase in number of PLBs and growth rates were obtained when using Vacin and Went medium 1 (VW1) in both culture steps compared with those in 15 other medium combinations. Starting from 0.5 g of PLBs, culturing on VW1 for 8 months achieved a total of 415.25 g of PLBs, a multiplication rate of 830-fold. The supplementation of tomato (Solanum lycopersicum) and substitution of ‘Hom Thong’ banana [Musa acuminata (AAA group)] with ‘Khai’ banana [M. acuminata (AA group)] in this new medium promoted growth and proliferation of dendrobium PLBs 2.4-fold over the control medium, suggesting its usefulness in commercial micropropagation.
Correlations Between Hybrid Bermudagrass Morphology and Wear Tolerance
Authors: Kowalewski Alexander R. , Schwartz Brian M. , Grimshaw Austin L. , Sullivan Dana G. , Peake Jason B.
Published: December 2018

Hybrid bermudagrasses (Cynodon dactylon × C. transvaalensis) typically have excellent wear tolerance when compared with other turfgrass species. This trait should be evaluated during variety development to reduce the risk of failure when new grasses are planted in areas with traffic stress. The objective of this research was to evaluate the wear tolerance of four hybrid bermudagrasses with differing morphological characteristics. Traffic was applied to the hybrid bermudagrass varieties ‘Tifway’, ‘TifSport’, and ‘TifTuf’, as well as an experimental hybrids (04-76) using a traffic simulator for 6 weeks. Leaf morphology (leaf width, length, and angle) and quantitative measure of density and color [normalized difference vegetation index ratio (NDVI), dark green color index (DGCI), and percent green turf color] were characterized before traffic, and then percent green turf color after 6 weeks of traffic was measured to estimate wear tolerance. ‘TifTuf’ hybrid bermudagrass provided the greatest wear tolerance, as well as the narrowest and shortest leaf lengths, greatest NDVI values and percent green color, and lowest DGCI before traffic. Conversely, 04-76 produced the poorest wear tolerance, as well as the widest and longest leaves, lowest NDVI values and percent green color, and highest DGCI values before traffic. Regression analysis determined that DGCI, leaf length, and leaf width were inversely, or negatively, correlated to wear tolerance, whereas percent green turf color before traffic was directly correlated to wear tolerance. For these hybrids, DGCI had the strongest correlation to increased wear tolerance.