bluuebunny/crossref_metadata_2025 huggingface dataset:
Watering Regime and Green Roof Substrate Design Affect Sedum Plant Growth
Authors: VanWoert Nicholaus D. , Rowe D. Bradley , Andresen Jeffrey A. , Rugh Clayton L. , Xiao Lan
Published: June 2019

Green roofs are an increasingly common, environmentally responsible building practice in the United States and abroad. They represent a new and growing market for the horticulture field, but require vegetation tolerant of harsh environmental conditions. Historically, Sedum species have been the most commonly used plants because, with proper species selection, they are tolerant of extreme temperatures, high winds, low fertility, and a limited water supply. A greenhouse study was conducted to determine how water availability influences growth and survival of a mixture of Sedum spp. on a green roof drainage system. Results indicate that substrate volumetric moisture content can be reduced to 0 m3·m–3 within 1 day after watering depending on substrate depth and composition. Deeper substrates provided additional growth with sufficient water, but also required additional irrigation because of the higher evapotranspiration rates resulting from the greater biomass. Over the 88 day study, water was required at least once every 14 days to support growth in green roof substrates with a 2-cm media depth. However, substrates with a 6-cm media depth could do so with a watering only once every 28 days. Although vegetation was still viable after 88 days of drought, water should be applied at least once every 28 days for typical green roof substrates and more frequently for shallower substrates to sustain growth. The ability of Sedum to withstand extended drought conditions makes it ideal for shallow green roof systems.
Isotopic and Nonisotopic Estimation of Nitrogen Uptake Efficiency in Container-grown Woody Ornamentals
Authors: Sandrock David R. , Righetti Timothy L. , Azarenko Anita N.
Published: June 2019

Cornus sericea L., Weigela florida (Bunge) A. DC., and Euonymus alatus (Thunb.) Sieb were grown outside in 3.8-L plastic containers for 345 days (1 Apr. 2001 to 11 Mar. 2002). Nitrogen (N) was applied at rates (NAR) of 25, 50, 100, 200, and 300 mg·L–1 and delivered as aqueous double-labeled 15N depleted NH4NO3 (min 99.95% atom 14N). In all species, root, shoot, and total plant dry weight increased with increasing NARs while root to shoot ratios decreased. Similarly, root, shoot, and total plant N increased with NAR for each species, and at each NAR more N was stored in the roots than in the shoots. Estimation of fertilizer N uptake determined by the total N method was higher for all species and at each NAR than estimation of N uptake determined by the fertilizer 15N tracer method. Fertilizer N uptake efficiency determined by the total N method was highest at 25 mg·L–1 and decreased as NARs increased. In contrast fertilizer N uptake efficiency determined by the fertilizer 15N tracer method was lowest at 25 mg·L–1 and increased or remained relatively constant as NARs increased. Differences in N uptake and N uptake efficiency can be attributed to overestimation by the total N method due to the inclusion of nonfertilizer N and underestimation by the fertilizer 15N tracer method due to pool substitution. Corrected N uptake efficiency values can be calculated by adjusting the original data (total N or 15N uptake) by the distance between the origin and the y intercept of the regression line representing the data.
Use of Trinexepac-ethyl for Growth Regulation of Chrysanthemum (Dendranthema ×grandiflora)
Authors: Gardner D.S. , Metzger J.D.
Published: June 2019

Trinexapac-ethyl (TE) [4-(cyclopropyl-α-hydroxy-methylene)-3, 5-dioxocyclohexanecarboxylic acid ethyl ester] is a plant growth regulator registered for use in turfgrass. The objective of the research reported in this paper was to determine if TE could be used in the production of florist chrysanthemums (Dendranthema ×grandiflora) to produce more compact, higher value plants. Foliar applications of TE to non-pinched plants of the tall cultivar `Billings' reduced canopy height 8% to 40% as the amount of applied TE was increased from 6.25 × 10–5 to 2.0 × 10–3 g. The effects of TE varied among chrysanthemum cultivars. Growth inhibition of pinched plants among the various cultivars ranged from 7% (`White Viewtime') to 23% (`White Graceland') 28 days following a single application of 1.0 × 10–3 g TE. In most cultivars, the inhibitory action of TE was not observed after 28 days. In fact some cultivars exhibited a rebound effect during the post-suppression growth phase in which internode extension rates were greater in TE-treated plants than controls. Both the number and timing of the TE application affected efficacy. A second TE application 5 weeks after the first treatment, or application of TE at the appearance of flower buds produced the highest quality crop in terms of uniformity and compactness, with overall height reduction generally 15% to 20%. No differences in flower color, number, or mass per flower were observed due to TE application.
Postgermination Drenches with PEG-8000 Reduce Growth of Salvia and Marigolds
Authors: Burnett Stephanie , Thomas Paul , van Iersel Marc
Published: June 2019

We previously found that incorporation of PEG-8000 into the growing medium delayed germination and resulted in shorter seedlings. However, in that study, we were unable to determine whether the reduced height was merely the effect of delayed germination or of reduced elongation after germination. To answer this question, we studied whether postgermination drenches with PEG-8000 can reduce seedling height. Annual salvia (Salvia splendens F. Sellow. ex Roem. & Shult. `Bonfire') and French marigold (Tagetes patula L. `Boy Orange') seedlings were treated with drenches of PEG-8000: 0, 15, 20, 30, 42, 50, 62, 72, or 83 g·L–1. At least 20% of seedlings treated with 62 to 83 g·L–1 of PEG-8000 were dead 14 d after treatment. Salvia and marigolds treated with the remaining PEG-8000 concentrations were up to 34% and 14% shorter than untreated seedlings, respectively. Leaf water (Ψw) and turgor potential (Ψp) also decreased for salvia which were grown with greater concentrations of PEG-8000, one probable cause of the observed reduction in elongation. Since the PEG-8000 in this study was applied after germination, it is clear that PEG-8000 does not reduce elongation merely by delaying germination, but also by reducing the elongation rate. Thus, postgermination drenches with PEG-8000 can be used to produce shorter seedlings.
Annual Flower Injury from Sublethal Rates of Dicamba, 2,4-D, and Premixed 2,4-D + Mecoprop + Dicamba
Authors: Hatterman-Valenti Harlene , Mayland Paul
Published: June 2019

Greenhouse experiments were conducted to compare visible injury from sublethal rates of 2,4-D, dicamba, and a premixed product of 2,4-D + mecoprop + dicamba for eight annual flowers and to describe herbicide injury symptoms for these annual species. Herbicides were applied at rates 0.05×, 0.1×, and 0.2× of their highest labeled rate for turfgrass to simulate spray drift conditions. Visible injury varied between species, herbicide rate, and time after herbicide application. Alyssum (Lobularia maritima Desv.) showed the greatest initial injury and ageratum (Ageratum houstonianum Mill.) showed the greatest injury at 4 weeks after treatment. Symptom severity increased as herbicide rate increased, with the greatest injury from the premixed product, followed by 2,4-D, and then dicamba. The eight species varied in their degree of visible injury and flower production to dicamba, 2,4-D, and the premixed product. Reduced flowering was most obvious for prolific flowering species such as alyssum. Impatiens (Impatiens wallerana L.), salvia (Salvia splendens Sello), and snapdragon (Antirrhinum majus L.) produced more flowers in response to sublethal dicamba rates compared to the untreated plant. All rates of 2,4-D generally reduced flowering compared to untreated plants, except the lowest rate of 2,4-D for geranium (Pelargonium xhortorum Bailey) and snapdragon. Dahlia (Dahlia hortensis Cav.) sprayed with dicamba at the highest rate produced three times as many stems as plants untreated or those sprayed with 2,4-D. Overall order of species susceptibility to sublethal rates of dicamba, 2,4-D, or the premixed product from most susceptible to least susceptible was ageratum > alyssum > marigold (Tagetes erecta L.) > dahlia > geranium = salvia = snapdragon = impatiens. Differences in overall susceptibility to the plant growth regulator herbicides evaluated should provide useful information to horticulturalists designing annual flower beds and borders and lawn care applicators.
Natural Field Spread of Decline and Nondecline Inducing Isolates of Citrus Tristeza Virus in Florida after the Introduction of the Brown Citrus Aphid
Authors: Powell C.A. , Pelosi R.R. , Burton M.S. , Rundell P.A. , Ritenour M.A. , Bullock R.C.
Published: June 2019

The effectiveness of seven different aphid control regimes in delaying movement of decline (DI) and nondecline (NDI) inducing isolates of citrus tristeza virus (CTV) into a CTV-free sweet orange scion on sour orange rootstock block was monitored annually for 5 years beginning in 1999, 2 years after the introduction of the brown citrus aphid (BrCA) into the region. After 5 years, the mean percentages of infection with DI CTV were 19, 19, 17, 29, 23, 19, or 14 for trees treated annually with imidocloprid, every 6 months with imidocloprid, every 3 months with imidocloprid, every 2 months with imidocloprid, annually with Temik, annually with Meta Systox-R, or untreated, respectively. The mean percentages of infection (after 5 years) with only NDI isolates of CTV for the seven treatments were 40, 31, 33, 38, 38, 38, or 33. There was no significant difference (after 5 years) among either the DI or NDI CTV treatment means. The overall 5-year infection percentage for DI CTV (20%) was somewhat lower than that reported before the introduction of the BrCA (27%) (11). Aphid densities (Toxoptera citricidus and Aphis spiraecola) varied considerably from year to year. Good aphid control was achieved with all four imidocloprid treatments, but not with Temik or Meta Systox-R. The level of aphid control did not influence overall CTV infection percentages.
Weed Control with Hydrophobic and Hydrous Kaolin Clay Particle Mulches
Authors: Takeda Fumiomi , Glenn D. Michael , Tworkoski Thomas
Published: June 2019

Three experiments were performed to determine the effect of amending the soil surface layer and mulching with hydrophobic kaolin particle on weeds and blackberry (Rubus subgenus Rubus Watson) plants. In the first study a processed kaolin material (product M-96-018, Engelhard Corporation, Iselin, N.J.), was incorporated in August into the top 3 cm of freshly roto-tilled field that had been in pasture the previous 5 years. The following spring, dry weight of weed vegetation in the control treatment was 219 g·m–2 and was significantly higher (P = 0.05) than the 24 g·m–2 harvested from the treated soil. In two other studies, planting holes for blackberry transplants were either 1) pre- or postplant mulched with a 2- or 4-cm layer of 5% or 10% hydrophobic kaolin in field soil (w/w), or 2) postplant treated with a) napropamide, b) corn gluten meal, c) a product comprised of hydrous kaolin, cotton seed oil, and calcium chloride in water (KOL), d) hand weeded, or e) left untreated. Although untreated plots had 100% weed cover by the end of July, herbicide treatments, 4-cm deposition of hydrophobic kaolin particle/soil mulch, and KOL all suppressed weeds the entire establishment year. Preplant application of hydrophobic kaolin mulch and postplant application of KOL reduced blackberry growth and killed transplants, respectively. In year 2, blackberry plants produced more primocanes that were on average 10-cm taller in weed-free plots (herbicide, 4-cm kaolin soil mulch, and mechanical weeding) than in weedy plots (control and 2-cm kaolin soil mulch). In year 3, yield was significantly lower in control plots (1.5 kg/plant) than in plots that were treated with napropamide and 2- and 4-cm hydrophobic kaolin mulch, or hand weeded during the establishment year (4 kg/plant). The results showed that 4-cm hydrophobic kaolin mulch applied after planting can suppress weeds without affecting blackberry productivity. These kaolin products are excellent additions to the arsenal of tools for managing weeds in horticultural crops.
Ripening-induced Chemical and Antioxidant Changes in Bell Peppers as Affected by Harvest Maturity and Postharvest Ethylene Exposure
Authors: Fox Abbie J. , Del Pozo-Insfran David , Lee Joon Hee , Sargent Steven A. , Talcott Stephen T.
Published: June 2019

Greenhouse-grown bell pepper (Capsicum annuum L. `Robusta') were harvested at five stages of maturation (10% red to full red) in early winter 2002 (Expt. 1) and at two stages (10% red and full red) in early Spring 2002 (Expt. 2). The fruit were subsequently stored at 20 °C in a continuous-flow chamber consisting of either 100 μL·L–1 ethylene (balance air) or air-only (control) at 90% relative humidity (RH). Individual fruit were removed from the chambers upon reaching full red color, and stored at –30 °C until physicochemical analyses were conducted. Harvest maturity, and ethylene exposure had no appreciable effect on pulp soluble solids content, total titratable acidity or pH. Exposure to ethylene hastened ripening time compared to the air control but was independent of fruit maturity at harvest. Fruit exposed to ethylene reached full-red color 6.4 days (Expt. 1) and 4 days (Expt. 2) earlier than air-only fruit, respectively. There were no significant phytochemical and antioxidant differences noted for total carotenoids, total ascorbic acid, and soluble phenolics at various maturity stages due to ethylene exposure. Appreciable differences were observed between the two experiments for phytochemicals and antioxidants, as bell peppers from the latter experiment contained at least twice the concentrations of phytochemicals and antioxidant capacity as those from the first experiment. Differences in these parameters between experiments were attributed to environmental factors such as average temperature, day length, and light intensity. Ethylene was demonstrated to be an effective postharvest treatment for accelerating color change in this bell pepper cultivar, permitting earlier harvest without altering phytochemical synthesis rates.
Genotypic Variability in Staminate Flower and Pollen Grain Production of Diploid Watermelons
Authors: Stanghellini Michael S. , Schultheis Jonathan R.
Published: June 2019

In 1999 and 2000, a total of 27 diploid watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] cultivars and advanced breeding lines (hereafter referred to as cultigens) were evaluated for staminate flower and pollen grain production to assess their potential to serve as pollenizers (pollen source plants) in triploid watermelon production systems. Male reproductive output (staminate flower and pollen production) was quantified during the peak flowering and fruit setting phase of the cultigens under field conditions. The number of staminate flowers produced per plant per day, number of pollen grains produced per flower, and total number of pollen grains produced per plant per day (staminate flowers per plant × pollen grains produced per flower) differed greatly among cultigens (for all tests, P < 0.01). Staminate flower production by cultigens differed by year (P < 0.0029) and days within years (P = 0.0225), but pollen production between years by cultigens was stable (P = 0.4841). Total male reproductive output ranged from 134,206 pollen grains per plant per day for `Jamboree' to 321,905 pollen grains per plant per day for `Summer Flavor 500'. These studies demonstrate the genotypic variability in watermelon male reproductive output potential, and may assist growers in choosing a good diploid pollenizer for triploid watermelon production.
Morphological Development of Lingonberry as Affected by In Vitro and Ex Vitro Propagation Methods and Source Propagule
Authors: Debnath Samir C.
Published: June 2019

The growth and development of lingonberry (Vaccinium vitis-idaea L.) plants propagated either by conventional softwood cuttings or by in vitro shoot proliferation from nodal explants and by shoot regeneration from excised leaves of micropropagated shoots, were studied in cultivars `Regal', `Splendor', and `Erntedank'. Significant differences were observed between the treatments. After 3 years of growth, the in vitro-derived plants produced more stems, leaves, and rhizomes than the conventional cuttings which rarely produced rhizomes. In vitro culture on nutrient medium apparently induces the juvenile branching characteristics that favor rhizome production. This increase in vegetative growth and rhizome yield of in vitro-derived plants over stem cuttings varied among genotypes.
Seed Germination of Rhamnus caroliniana: Implications for Ecology and Horticulture
Authors: Stewart J. Ryan , Graves William R.
Published: June 2019

Little is known about the reproductive biology of carolina buckthorn [Rhamnus caroliniana Walt. or Frangula caroliniana (Walt.) Gray], an attractive North American shrub or small tree that might merit increased use in managed landscapes. The fecundity and high germinability of seeds of the Eurasian common buckthorn (Rhamnus cathartica L.), however, have been characterized as factors contributing to its invasiveness. We compared seed germination of these species to ascertain how easily carolina buckthorn could be grown from seed in nurseries and to acquire data for predicting whether carolina buckthorn might be invasive if introduced into managed landscapes. Fruits of carolina buckthorn were collected from indigenous plants in central Missouri, southern Oklahoma, and southern Texas. Fruits of common buckthorn were collected from shrubs naturalized in central Iowa. Seeds of both species were stratified for up to 112 days in darkness at 4 °C; germination at 24 °C in the dark was then evaluated for 56 days. Quadratic functions best described how time of stratification influenced germination value and germination percentage of common buckthorn, whereas these measures of carolina buckthorn were best represented by exponential (value) or linear (percentage) functions. Stratification for 112 days maximized germination value and percentage for carolina buckthorn within the 56-day germination period, but shorter stratifications were sufficient to optimize germination of common buckthorn. While the overall mean germination of carolina buckthorn was 40%, results varied by provenance and ranged from 25% (Missouri) to 56% (Oklahoma). Mean germination of common buckthorn over times of stratification was 71%, and the overall mean daily germination of common buckthorn, 1.3, was 86% greater than that of carolina buckthorn, 0.7. We conclude that seeds of carolina buckthorn are more resistant to germination than seeds of common buckthorn. Our results suggest that plant propagators should cold-stratify seeds of carolina buckthorn for up to 112 days, and suggest that carolina buckthorn has a lower potential to be invasive than does common buckthorn.
Effect of Scarification, Seed Storage Temperature, and Relative Humidity on Lupinus havardii Wats. and Lupinus texensis Hook. Seed Germination
Authors: Mackay Wayne A.
Published: June 2019

Seeds of Lupinus havardii Wats. and L. texensis Hook. were subjected to scarification, storage temperature (4 or 22 °C), and relative humidity (RH) treatments (11%, 23%, 52%, 75%, or 97% RH) for 12 months. Seed moisture increased as relative humidity increased with scarified seed having the greatest increase in seed moisture content regardless of storage temperature. For both species, the combination of seed scarification before storage, 75% RH, and 22 °C storage temperature resulted in a significant and rapid decline in germinability beginning at 4 months. Scarified L. texensis seed stored at 52% RH and 22 °C also exhibited a significant decline in germinability following 6 months storage. Seed of both species stored under all other conditions germinated similar to or higher than the initial germination rate after 12 months. These results clearly show that scarification can be performed before seed packaging as long as the seed packets are stored at ≤23% RH under 4 or 22 °C with no loss in germinability for at least 1 year.
Root Zone Temperatures of Viburnum odoratissimum Grown in the Multipot Box System and Conventional Systems: Measurement and Analyses of Temperature Profiles and Predicting Root Zone Temperatures
Authors: Irmak Suat , Haman D.Z. , Irmak A. , Jones J.W. , Tonkinson B. , Burch D. , Yeager T.H. , Larsen C.
Published: June 2019

This research study evaluates the effectiveness of a recently introduced irrigation-plant production system, multipot box system (MPBS), for moderating root zone temperature (RZT) compared with the conventional nursery containers. The study also deals with the development, calibration, and validation of a series of models that can be used to predict maximum (max) and minimum (min) RZTs using commonly available input variables. The Viburnum odoratissimum (Ker.-gawl.) was used as the test plant. Models were calibrated in the fall growing season and validated during the summer. The RZT was used as the dependent variable while the max and min air temperatures (Tmax and Tmin) and/or incoming solar radiation (Rs) were used as independent variables. The color of the MPBS had an effect on plant growth. Plants grown in the white MPBS had higher growth indices, shoot and root dry weights, and number of stems as compared with the plants in the black MPBS or the conventional (control) system (CS). White MPBS maintained cooler RZTs than the max air temperature during both seasons. Also, white MPBS maintained cooler RZTs than the black MPBS and CS during the two seasons. In both seasons, water temperature in the black MPBS was higher than the temperature in the white MPBS contributing to the high RZTs in the black MPBS. The RZT of the black MPBS and CS exceeded the critical value (40 °C), which is cited in the literatures as negatively impacting root growth, water and nutrient uptake, leaf area, plant survival, root and shoot dry weights, water status, and photosynthesis. The RZT in the CS was above 45 °C for most of the summer season and plants were exposed to this extreme temperature for a few hours a day during most of the summer. The white MPBS provided a better environment and enhanced plant growth. For regions where ambient air temperature ranged from 2 to 41 °C, the white MPBS can provide adequate and effective RZT protection for plants grown in No. 1, 3.8-L standard black conventional containers. Predicted RZT values were well correlated with measured values in all systems. Rs did not have an effect on predicting RZTmax in the MPBS treatments. Wind speed did not contribute to predicting RZT in any production systems. The root mean square error between measured and predicted RZT was relatively low ranging from 0.9 to 2.8 °C. Models were able to explain at least 74% of the variability in RZTs using only Tmax, Tmin, and/or Rs. Models developed in this study should be applicable for estimating RZTs when similar management and cultural practices are present. Models of this study are practical, simple, and applicable to predict RZTs where ambient air temperature ranges from 1.9 to 40 °C. Model results should not be extrapolated beyond these limits.
Dissolved Organic Carbon in Soil from Compost-amended Bermudagrass Turf
Authors: Wright Alan L. , Provin Tony L. , Hons Frank M. , Zuberer David A. , White Richard H.
Published: June 2019

Application of organic amendments can increase dissolved organic C (DOC) concentrations, which may influence movement of nutrients and heavy metals in soils. The objectives of this study were to investigate the influence of compost sources and application rates on concentrations of soil DOC, NO3-N, and extractable P over 29 months after a one-time application of compost to bermudagrass [Cynodon dactylon (L.) Pers.] turf. Few differences were evident between compost sources for soil total organic C (TOC), DOC, and NO3-N. However, the initial P content of compost sources significantly influenced soil extractable P. Increasing the rate of compost application increased soil TOC initially, but levels remained fairly stable over time. In contrast, DOC continued to increase from 3 to 29 months after application, suggesting that compost mineralization and growth of bermudagrass contributed to DOC dynamics in soil. Dissolved organic C was 98%, 128%, 145%, 175%, and 179% greater 29 months after application of 0, 40, 80, 120, and 160 Mg compost/ha, respectively, than before application. Rate of compost application had less effect on DOC than TOC, as DOC concentrations appeared controlled in part by bermudagrass growth patterns. Soil NO3-N was generally unaffected by compost application rate, as NO3-N decreased similarly for unamended soil and all compost treatments. Soil extractable P initially increased after compost application, but increasing the application rate generally did not increase P from 3 to 29 months. Seasonal or cyclical patterns of TOC, DOC, and extractable P were observed, as significantly lower levels of these parameters were observed in dormant stages of bermudagrass growth during cooler months.
Soil CO2 Concentration Effects on Creeping Bentgrass Grown under Various Soil Moisture and Temperature Conditions
Authors: Rodriguez Ian R. , McCarty Lambert B. , Toler Joe E. , Dodd Roy B.
Published: June 2019

Use of creeping bentgrass [Agrostis stoloniferous L. var. palustris (Huds.)] on golf greens has expanded into the hotter, more humid regions of the United States where its quality is often low during summer months. The summer decline in bentgrass quality may be partially attributed to respiration rates exceeding photosynthesis during periods of supraoptimal temperatures and adverse soil conditions, such as excessive CO2 and inadequate O2 levels. The objectives of this study were to examine the effects of high temperature, high soil CO2, and irrigation scheduling on creeping bentgrass growth. A growth chamber study was conducted using `A-1' creeping bentgrass. Treatments included all combinations of three day/night temperature regimes (26.5/21 °C, 29.5/24 °C, and 32/26.5 °C), three irrigation schedules (field capacity daily, field capacity every two d, and half field capacity daily), and four soil CO2 injection levels (10%, 5%, 0.03%, and a noinjection control). Creeping bentgrass shoot and root dry weights and net photosynthetic rates were greater for day/night temperatures <32/26.5 °C. High temperatures (32/26.5 °C) and 10% CO2 reduced bentgrass net photosynthesis by 37.5 μmol CO2/m2/s. Shoot and root total nonstructural carbohydrates also were lowest for highest temperature regime. Respiration exceeded gross photosynthesis at 32/26.5 °C when 5% and 10% CO2 injection levels were used, indicating a carbon deficit occurred for these conditions. Irrigation volume and frequency did not affect bentgrass growth. High temperatures combined with high soil CO2 levels produced poorest turf quality.
Effects of Nitrogen and Potassium Fertilization on Perennial Ryegrass Cold Tolerance During Deacclimation in Late Winter and Early Spring
Authors: Webster D.E. , Ebdon J.S.
Published: June 2019

Turf loss from freezing injury results in costly re-establishment, especially with turfgrasses such as perennial ryegrass (Lolium perenne L.) having poor low-temperature hardiness. Studies are limited as to the influence of N and K on cold tolerance during dehardening periods in late winter when grasses are most susceptible to freezing injury. The objective of this study was to evaluate perennial ryegrass low temperature hardiness during deacclimation in response to N and K and associated effects on crown hydration, median killing temperature (LT50), shoot growth rate, tissue K concentration, soil exchangeable K, and low temperature disease. Treatments included five rate levels of N (49, 147, 245, 343, and 441 kg·ha-1·yr-1) in all factorial combinations with 3 rate levels of K (49, 245, and 441 kg·ha-1·yr-1). Low temperature tolerance was assessed using whole plant survival and electrolyte leakage (EL). Interactions between N and K were detected for all field measurements. The effects of N and K on survival LT50 were detected only during late winter periods in February 2004, N and K differences were lost by March. Late winter cold survival was negatively correlated with crown moisture, growth rate, and tissue K. Tissue K concentrations ranged from 28.6 to 35.9 g·kg–1 DM while soil K ranged from 121 to 261 mg·kg–1. Soil extractable K was not correlated with tissue K. Survival and EL LT50 were uncorrelated due to N and K interaction. Survival LT50 ranged from –9.0 to –13.6 °C. Maximum cold hardiness occurred when low to moderate N (49 to 147 kg·ha-1·yr-1) was applied with medium-high to high levels of K (245 to 441 kg·ha-1·yr-1), which corresponded to soil exchangeable K levels ranging from 200 to 260 mg·kg–1. Alternatively, similar K fertilization and soil K levels combined with high rates of N (343 and 441 kg·ha-1·yr-1) increased freeze stress and low temperature fungi (Typhula incarnata). At N rates routinely applied to perennial ryegrass, higher soil extractable K beyond those levels currently recommended for optimum shoot growth could provide some benefit in enhancing cold hardiness. Late fall applied N did not appear to increase the potential for winter injury.
AN IN-DEPTH SURVEY OF SWEETPOTATO PACKING AND HANDLING PROCEDURES IN NORTH CAROLINA
Authors: Edmunds B.A. , Holmes G.J.
Published: June 2019

Methods of packing and handling sweetpotatoes are important for mitigating postharvest losses due to decay. The goal of this work is to take a critical look at the packing and handling processes in North Carolina (NC) sweetpotato packinghouses. Similar surveys are being conducted in Louisiana and Mississippi as part of a multi-state project. The survey is inclusive of all packingline operations including sequence of machinery components, length and speed of the packingline, decay control products/strategies used, and impact (bruising) measurements. Packingline impacts are quantified and characterized using a SmartSpud. This instrumented device is placed on the packingline where it is conveyed alongside sweetpotatoes, measuring the impact forces exerted and sending the data via a radio signal to a handheld personal digital assistant (PDA). The information on the PDA is downloaded onto a computer where the results can be displayed in more detail and analyzed. Packinghouse personnel respond well to this visual display and willingly spend one hour being interviewed, discussing the results of the survey, learning about the trouble spots on their lines, and getting advice on how to reduce potential injuries. About 15 out of 30 NC packinghouses have been surveyed (this includes all of the high-volume packinghouses). We typically found the largest impacts (30–70 G) occurring during dumping and at unprotected conveyor changes. Packinglines vary in length from 88 ft to 277 ft with run time varying from 3.5 min to >10 min. Lines all share the same basic components (dump, eliminator, brushbeds, sizer, etc.) with layout and design modified to suit individual needs and space requirements. A variety of decay control methods are in use with about one half of packers surveyed routinely applying the fungicide Botran.
EFFECT OF ALTERNATIVE POSTHARVEST DIP TREATMENTS ON RHIZOPUS SOFT ROT OF SWEETPOTATO
Authors: Edmunds B.A. , Holmes G.J.
Published: June 2019

Most sweetpotato packers use the fungicide Botran (dicloran) to reduce losses caused by Rhizopus soft rot. However, certain markets are no longer accepting Botran-treated sweetpotatoes and packers are searching for suitable alternatives. We evaluated 12 products applied as dip treatments for their ability to control Rhizopus soft rot. Sweetpotato roots (`Hernandez') were wounded and artificially inoculated with a Rhizopus spore suspension (106 spores/mL). Roots were dipped for 30 sec. in treatment solutions and stored at about 65 °F. After 10 days, roots were evaluated for incidence of decay. The inoculation method produced 100% decay in nontreated roots. Bio-Save 11LP and Pristine, a biopesticide (strain of Pseudomonas syringae) and reduced-risk chemistry respectively, both provided very high levels of decay control. Other products such as Biosave 10LP (a different strain of P. syringae), Scholar and Freshgard 25 were marginally effective, while copper ionization, bleach, and Storox were ineffective against Rhizopus soft rot.
USING GIS TO ANALYZE SWEET POTATO WEEVIL TRAP DATA IN LOUISIANA
Authors: Villordon Arthur , Roussel Craig , Hardy Tad
Published: June 2019

The Louisiana Department of Agriculture and Forestry (LDAF) conducts sweetpotato weevil (SPW) (Cylas formicarius Fabricius) monitoring as part of the statewide SPW quarantine program. This activity involves a statewide pheromone-based trapping program that monitors sweetpotato beds and production fields. We conducted GIS analysis of SPW trap data, collected over three years, to assess the potential use of publicly available GIS tools in managing and interpreting the data. Trap data was mapped to specific beds and fields in each of three years, generating layers that clearly showed fields and parishes that reported high trap counts. GIS analysis showed potential SPW hotspots in each year, indicating that certain beds or fields are predisposed to SPW infestation than others. This information can be useful in planning SPW management strategies by growers and other stakeholders. The GIS database also provides the foundation for the development of descriptive and predictive models of SPW occurence not only in Louisiana, but in other states where SPW is a potential pest. For example, using presence data for Louisiana and Genetic Algorithm for Rule Set Prediction (GARP), a GIS-based ecological niche modelling tool, we were able to generate predicted distribution using mean minimum temperature for January as the predictor variable. Although additional work is needed to identify other predictor variables and verify the models, the results demonstrate the potential use of GIS-based tools for generating warnings or advisories related to SPW.
ADULT AND LARVAL BIOASSAYS FOR DETERMINING RESISTANCE OF SWEETPOTATO GENOTYPES TO Diabrotica SPP.
Authors: Jackson D. Michael , Bohac Janice R.
Published: June 2019

Production of sweetpotatoes is severely limited by several insect pests, and new pest management approaches for this crop are needed. A host plant resistance research program typically depends on reliable bioassay procedures to streamline evaluation of germplasm. Thus, bioassay procedures were developed for both adults and larvae of two cucumber beetle species (Diabrotica balteata and D. undecimpunctata). For the adult bioassay, a piece of sweetpotato peel (periderm & cortex with stele removed) was embedded periderm-side up in plaster in a Petri dish, and a single adult was placed on it. Plugs were changed as needed and adult longevity was measured. A laboratory bioassay also was developed for Diabrotica larvae. Plugs (0.9 cm diameter) of sweetpotato peel or stele were placed periderm-side up into sterile microcentrifuge tubes (1.5 mL) containing 0.5 mL water-agar to prevent desiccation. One second instar Diabrotica was added to each micro centrifuge tube, which was held at 25 °C for 12 days. Surviving larvae were weighed. Diabrotica larvae grew larger when they were fed stele than when they were fed peels of any sweetpotato genotype. Larval growth was not different among genotypes for any of the stele treatments. However, larval growth on the peel of the resistant genotypes (Regal and W-375) was significantly lower than for the susceptible cultivars Beauregard or SC1149-19. These bioassays were consistent with field results, indicating that these techniques could be useful for evaluating pest resistance in sweetpotato genotypes for Diabrotica and other insect species.
MASTER GARDENER UNIVERSITY: A PILOT LEADERSHIP/ADVANCED TRAINING EVENT
Authors: Kelly Lelia S.
Published: June 2019

In a time of budgetary constraints, new strategies have to be developed if we are to continue to meet the demand for home horticulture information. This on-campus event was developed as one of those strategies. The goal of this event was to provide a train-the-trainer opportunity that would equip selected Master Gardeners to assume a larger role in the delivery of home horticulture information. Training needs were determined and included advanced training in insect and disease management, leadership, presentation skills, and computer skills. Educational materials were provided and “graduates” were given the charge of going back to their county groups and sharing what they had learned. Other goals of the event were to provide an opportunity to tour campus facilities, meet key university personnel, and provide recognition and motivation. Sixty-eight Master Gardeners attended this two-day pilot event in May. On-site evaluations were very positive with attendees ranking the educational sessions most beneficial of the activities provided. Year end reporting from the counties indicated that Master Gardeners conducted 82% more public programs in 2004, 49% more home visits and handled 18% more homeowner calls. Part of this substantial increase in program delivery can be contributed to the training these volunteers received at this event. Personal communication with county directors and Master Gardeners indicate that these volunteers are assuming more of a leadership role in the management of the county Master Gardener
MANAGING A REGIONAL USDA-FUNDED FOOD SAFETY PROGRAM
Authors: Osborne Dennis J. , Sanders Douglas C. , Ward Donn R. , Rushing James W.
Published: June 2019

This paper summarizes the management framework of a multi-state, multi-institutional partnership delivering a targeted train-the-trainer program. The program provided Good Agricultural Practices (GAPs) and Good Manufacturing Practices (GMPs)-based training to southeastern U.S. fresh fruit and vegetable (produce) growers and packers. Twelve southern U.S. states cooperated in this project: Arkansas, Florida, Georgia, Kentucky, Louisiana, Mississippi, North Carolina, Oklahoma, South Carolina, Tennessee, Texas, and Virginia. The 2000–04 work was funded by United States Department of Agriculture – Cooperative State Research, Education, and Extension Service (USDA–CSREES) National Food Safety Initiative grants. This project developed materials, pilot tested them, refined them for use by a regional group of specialized agents, assisted the agents in delivering the new programming and evaluated the results.
DISTANCE EDUCATION FOR GRADUATE AND IN-SERVICE TRAINING FOR AGENTS
Authors: Sanders Douglas C. , Osborne Dennis J.
Published: June 2019

Many potential students, because of distance from the University campus and/or job requirements, cannot take traditional courses on-campus. This group of learners is place-bound—a group of learners who may be employed full-time, most-likely married with job responsibilities and/or other situations demanding most of their attention. These persons are the very definition of nontraditional, and their educational needs demand non-traditional pedagogy. Their maturity and self-directedness eliminate many concerns often voiced about extending support and evaluation inherent in maintaining quality for and among students adopting Distance Education (DE). In North Carolina, the audience is large and demands that the University reach out to them. Cooperative Extension's more than 120 Horticultural Crops Extension Agents (field faculty) and over 300 other field faculty whose interests include horticultural topics constitute students identifiable as likely enrollments for credit taking hours off-campus. Distance Education can overcome these problems in several ways. First, high demand, low-seat-available classes can offer additional enrollment for credit if open to Distance students. Second, courses can be offered asynchronously or with alternative delivery. Finally, courses offered collaboratively among institutions generate a level of interest and enthusiasm that may not exist for home-grown courses. Such efforts as these are creating a Distance Education program in NCSU's Horticultural Science Department.
THE SOUTHEASTERN VEGETABLE CROPS GUIDELINES AND SEVEW MEETING
Authors: Kemble J. M. , Kelly W. T. , Holmes G. J. , Sanders D. C.
Published: June 2019

Initiated by DC Sanders, the Southeastern Vegetable Crops Guidelines (SVCG) represents a major regional collaborative effort of Extension Specialists from Alabama, Louisiana, Georgia, Mississippi, North Carolina, and South Carolina whose aim is to produce an annually updated, all-in-one, fits on the dashboard of your truck reference for commercial vegetable growers and Extension workers for the Southeastern US. The first edition was developed in 1998 and published in 1999 as a “for pay” publication, but subsequent editions have employed a partnering with a corporate sponsor and publication company resulting in faster turnaround for printing and a no-cost publication. Each August, a team of Extension Vegetable Specialists, Extension Plant Pathologist, Extension Weed Specialists and Extension Entomologist from around the southeastern US meet for the Southeastern Extension Vegetables Workers (SEVEW) meeting. At this 2-day meeting, the participants' primary focus is to review, rewrite, refine, and update the current year's recommendations for the next edition of the SVCG. Although this publication is mainly used by the states listed, researchers and specialists from other states (FL, KY, OK, VA, TN) annually participate in this meeting. The SEVEW meeting has developed into an opportune forum for dialogues and exchanges updating each other as to the present critical issues in our respective states. Several land-grants are in the process of or are counting the SVCG/SEVEW as part of their federally-mandated multistate programming. Additionally, the SEVCG and SEVEW meeting are officially recognized as a Regional Project by CSREES. The 2005 edition can be found at http://www.aces.edu/dept/com_veg/2005_SEVCG.pdf.
DEVELOPING PESTICIDE CERTIFICATION TRAINING FOR HISPANICS WORKING IN THE GREEN INDUSTRIES
Authors: Asuaje Cesar , County Palm Beach , Garofalo Joe
Published: June 2019

Hispanic agricultural workers are difficult to reach and educate. Many can't benefit from Extension programs because of the language barrier, education level and social factors. Safety (WPS) and Pesticide Applicator certification are required for workers to find employment and advance. In Florida, the total non-fatal agricultural occupational injuries among Hispanic workers rose 33% between 1999 and 2001, and total fatal injuries rose 18% between 1999 and 2002. Florida laws require that pesticide applicator exams be in English. Many Hispanics have experience and knowledge in pesticide use, but lack of sufficient language skills prevents their becoming certified. The University of Florida is addressing this issue with an extension agent whose main responsibility is to design and deliver programs in Spanish. First, we assessed the needs and started networking within the Hispanic community. Concurrently, training programs were developed in WPS and 7 certification categories in greatest demand. These have been offered in 11 south Florida counties to 4000+ workers. After each class, presentations were modified to incorporate effective content and methods, based on surveys and test scores. Among participants who took an exam, the passing rate has risen from below 50% to above 60%. The following have given good results: use two native speakers (Spanish and English); conduct the class in Spanish, but emphasize written and spoken English words; both trainers must interact with the audience; use props or good illustrations; teach at all levels, but recommend the exam only to those who can read an English label.
EFFECTS OF WATERMELON GRAFTING ON FRUIT YIELD AND QUALITY
Authors: Roberts Warren , Fish Wayne , Bruton Benny , Popham Tom , Taylor Merritt
Published: June 2019

Grafted cucurbits are commonly grown in various Asian and European countries, but only rarely in North America. Disease control in fields where crop rotation cannot be practiced is a common justification for grafting cucurbits. In the present study, grafting is being examined as a methyl bromide alternative, which may allow cucurbits to be grown in fields where heavy disease pressure would make production of nongrafted cultivars impractical. A study with watermelons (Citrullus lanatus) grafted onto rootstocks of squash and gourd was conducted at Lane, Oklahoma in 2004. Treatments consisted of watermelon cultivars SF 800, SS 5244, SS 7167, SS 7177, and SS 7187 from Abbot & Cobb Seed Co., grown on their own roots, or grafted onto rootstocks of RS1330, RS1332, RS1420, or RS 1421. Controls consisted of nongrafted cultivars Sangria, Royal Sweet, Jubilee, and Jamboree. Two fields were planted, with three replications per field. Plants were grown on 1 m centers, with rows 3 m apart. Yields of grafted plants were generally equal to or greater than the nongrafted plants. Sugar content, measured as soluble solids, was affected minimally, if any, by grafting. Lycopene content of fruit from grafted plants was equal to, or marginally better than, fruit from nongrafted plants. Fruit firmness, as measured by a penetrometer, was significantly greater in the grafted fruit than in the nongrafted fruit. The firmest fruit occurred with SS 7167 scions, grafted onto RS 1420 rootstock, which had a value of about 2.0 × 105 Pascals. The nongrafted plants had values of about 1.0 × 105 Pascals, or less. Matching of scions with appropriate rootstocks was important, as interactions did occur. Certain combinations were significantly superior to other combinations. We estimate that the cost to purchase a grafted seedling plant from a seedling supplier would be $0.75 to $1.00, which would include the cost of the seed and the grafting operation. This cost would compare favorably with the cost of applying methyl bromide to the soil and then planting nongrafted seeds or transplants. Higher plant survival due to disease resistance along with planting fewer plants per hectare is anticipated with grafted plants. The high values in fruit firmness in grafted fruit should be of particular interest to the fresh-cut industry.
IDENTIFYING AMOUNTS AND TYPES OF ANTHOCYANINS IN CULTIVARS AND BREEDING LINES OF COWPEAS
Authors: Dodson Hallie G. , Murphy J.B. , Morelock T.E.
Published: June 2019

Anthocyanins are naturally occurring plant pigments that are classified as flavonoids. Anthocyanins have important antioxidant properties which may help in prevention of cancer, arthritis, and cardiovascular disease. Finding common sources and possibly increasing levels of anthocyanins in food could be important to human health. This research project determined amount and type of anthocyanins in 16 cultivars and breeding lines of cowpeas (Vigna unguiculata). The information obtained from this research project will be used to improve anthocyanin content of cowpeas by breeding. Of the 16 cultivars and breeding lines, only a black cowpea breeding line, 95-356, contained measurable levels of 3 types of anthocyanins: delphinidin, peonidin, and an unknown anthocyanin. Total anthocyanin content was 0.00242 mg·g–1, which is equal to 0.21 mg per ½-cup serving. In another study with 95-356 Rabi A. Musah, found a total anthocyanin content of 121.26 mg per serving and also found three other types of anthocyanins. The difference in the studies could be explained by the storage time of two weeks after the anthocyanins were extracted, but before they were eluded in this study. Additional studies are needed to determine if cowpeas can provide anthocyanin levels comparable to other fruits and vegetables.