bluuebunny/crossref_metadata_2025 huggingface dataset:
In Situ Soil-water Characteristic Curves for Tropical Fruit Orchards in Trenched Calcareous Soil
Authors: Núñez-Elisea Roberto , Schaffer Bruce , Zekri Mongi , O'Hair Stephen K. , Crane Jonathan H.
Published: December 2018

Most tropical fruit trees in southern Florida are grown in calcareous gravelly soil that is mechanically trenched to a depth of about 50 cm (about 20 inches). Fruit trees are often planted at the intersections of perpendicular trenches to provide space for root development. Tree root systems are concentrated in the top 10 to 20 cm (about 4 to 8 inches) of soil. Extreme soil rockiness has made it difficult to obtain consistent and reliable measurements of soil water status and to collect soil samples for constructing soil-water characteristic curves in the laboratory. Multisensor capacitance probes andlow-tension [0 to 40 kPa (centibars) (0 to 5.8 lb/inch2)] tensiometers were installed adjacent to star fruit (Averrhoa carambola L.) and avocado (Persea americana Mill.) trees in trenches to simultaneously measure volumetric soil water content and soil matric potential in situ. Capacitance probes consisted of four sensors centered at depths of 10, 20, 30, and 50 cm (3.9, 7.9, 11.8, and 19.7 inches). Tensiometers were installed at 10- and 30-cm depths, adjacent to the 10- and 30-cm deep capacitance sensors. Measurements obtained with both instruments were used to generate in situ soil-water characteristic curves. Rock fragments were more abundant at 30 cm than at 10 cm (71% to 73% versus 26% to 38% of bulk soil volume, respectively) soil depth, which limited the precision of tensiometers at the greater depth. In situ soil water characteristic curves for the 10-cm soil depth can be used to determine parameters needed for irrigation scheduling by techniques such as the water budget method.
Performance of Strawberry Cultivars on Fumigated and Nonfumigated Soil in Florida
Authors: Chandler C.K. , Legard D.E. , Noling J.W.
Published: December 2018

Five strawberry (Fragaria ×ananassa Duch.) cultivars in the 1995-96 season and four cultivars in the 1996-97 season were grown in the annual hill plasticulture system, with and without preplant soil fumigation (98% methyl bromide/2% chloropicrin at a rate of 240 lb/acre [269 kg·ha-1]). These trials were established on land that had been cropped with strawberries for 20 years. Significant cultivar by fumigation interactions were not detected for either yield or average fruit weight. Plants grown in nonfumigated soil produced 54% and 68% of the yield obtained from the plants grown in fumigated soil in 1995-96 and 1996-97 respectively, and the average fruit weight from plants grown in nonfumigated soil was also reduced, compared to that of plants grown in fumigated soil. Plant mortality was ≤3% in the nonfumigated plots. These results indicate that strawberry productivity in Florida can be substantially reduced by growing plants in soil that has not been fumigated prior to planting, even in the absence of lethal pathogens.
Substrate Nutrient Retention and Growth of Container-grown Plants in Clinoptilolitic Zeolite-amended Substrates
Authors: Broschat Timothy K.
Published: December 2018

Downy jasmines [Jasminum multiflorum (Burm. f.) Andr.] and areca palms [Dypsis lutescens (H. Wendl.) Beentje & J. Dransf.] were grown in containers filled with a fine sand soil (SS) or with a pine bark-based potting substrate (PS). Each of these substrates was amended with 0%, 10%, or 20% clinoptilolitic zeolite (CZ) by volume. Plants were fertilized monthly with a water-nonsoluble 20N-4.3P-16.6K granular fertilizer. Downy jasmines were larger and had darker color in CZ-amended PS and were larger in CZ-amended SS than in nonamended SS or PS. Areca palms, which tend to be limited by K in SS had better color and larger size when the SS was amended with CZ. In PS, where K is seldom limiting, areca palms did not respond to CZ amendment of the PS. Both ammonium (NH4)-N and potassium (K) were retained against leaching by CZ, but some of the NH4-N adsorbed to CZ was subject to nitrification, either before or after its release into the soil solution. Some phosphate (PO4)-P was also retained by CZ.
Siberian Ginseng
Authors: Li Thomas S.C.
Published: December 2018

Siberian ginseng [Eleutherococcus senticosus (Rupr. ex. Maxim.) Maxim] is currently a popular medicinal plant in Eurasia and North America. It has been used by the Chinese for over 2000 years. Recently, imported products of this plant have become available in North America, with a market share of 3.1% of the medicinal herbal industry. Siberian ginseng is harvested from its natural habitat in Russia and northeast China. Overharvesting has resulted in this popular herb approaching endangered species status. Cultivation is the only way to avoid its extinction, and to ensure the correct identity. Siberian ginseng is not a true ginseng (Panax quinquefolium L. or P. ginseng C.A. Meyer), but it has its own bioactive ingredients with unique and proven medicinal values. However, standardization and quality control of the active ingredients in the marketed products, which are mainly imported from China, are needed to avoid mislabeling or adulteration with other herbs.
A Forced Ventilation Micropropagation System for Photoautotrophic Production of Sweetpotato Plug Plantlets in a Scaled-up Culture Vessel: II. Carbohydrate Status
Authors: Wilson Sandra B. , Heo Jeongwook , Kubota Chieri , Kozai Toyoki
Published: December 2018

Sweetpotato [Ipomoea batatas (L.) Lam., `Beniazuma'] plantlets were grown photoautotrophically (without sugar) for 12 days in an improved forced ventilation system designed with air distribution pipes for uniform spatial distributions of carbon dioxide (CO2) concentration. Enriched CO2 conditions and photosynthetic photon flux (PPF) were provided at 1500 μmol·mol-1 and 150 μmol·m-2·s-1, respectively. The forced (F) ventilation treatments were designated high (FH), medium (FM), and low (FL), corresponding to ventilation rates of 23 mL·s-1 (1.40 inch3/s), 17 mL·s-1 (1.04 inch3/s), and 10 mL·s-1 (0.61 inch3/s), respectively, on day 12. The natural (N) ventilation treatment was extremely low (NE) at 0.4 mL·s-1 (0.02 inch3/s), relative to the forced ventilation treatments. Total soluble sugar (TSS) and starch content were determined on day 12. Total soluble sugars (sucrose, glucose, fructose) of FH plantlets were lowest in leaf tissue and highest in stem tissue as compared to other ventilation treatments. Starch concentration was higher in leaf tissue of FH or FM plantlets as compared to that of FL or NE plantlets. Plantlets subjected to FH or FM treatments exhibited significantly higher net photosynthetic rates (NPR) than those of the other treatments; and on day 12, NPR was almost five times higher in the FH or FM treatment than the FL or NE treatments. Carbohydrate concentration of plantlets was also influenced by the position of the plantlets in the vessel. Within the forced ventilation vessels, leaf TSS of FH and FM plantlets was similar regardless of whether plantlets were located near the inlet or outlet of CO2 enriched air. However, under FH or FM conditions, leaf starch concentration was higher in plantlets located closest to the CO2 inlet as compared to the outlet.
Using a Seedling Hypocotyl Elongation Assay as a Genetic Screen for Ethylene Sensitivity of Seedling Geranium Cultivars
Authors: Clark David G. , Dervinis Christopher , Barrett James E. , Nell Terril A.
Published: December 2018

Experiments were conducted to determine if the seedling hypocotyl elongation and petal abscission assays could be used to identify differences in ethylene sensitivity among seedling geranium (Pelargonium ×hortorum) cultivars. When seedlings of six geranium cultivars were germinated and grown in the dark in the presence of the ethylene biosynthetic precursor 1-aminocyclopropane-1-carboxylic acid (ACC) at various concentrations, they exhibited the triple response (measured as reduced hypocotyl length). While seedlings from all six cultivars were sensitive to ACC, `Scarlet Elite' seedlings were most sensitive, and `Multibloom Lavender', `Elite White' and `Ringo 2000 Salmon' seedlings were the least sensitive when germinated and grown on 20 mm [2022 mg·L-1 (ppm)] ACC. Florets representing three developmental stages of each of the six cultivars were exposed to 1 μL·L-1 of exogenous ethylene for 0, 30, or 60 min to determine if differences in cultivar sensitivity could be determined for petal abscission. Of the six cultivars tested, `Ringo 2000 Salmon', `Multibloom Lavender' and `Elite White' were the least ethylene sensitive. Florets were also self-pollinated to test for cultivar differences in ethylene synthesis and subsequent petal abscission. Ethylene production and petal abscission were both promoted in self-pollinated florets compared to nonpollinated florets. `Ringo 2000 Salmon', `Multibloom Lavender' and `Elite White' florets produced similar amounts of ethylene as all other cultivars, but abscised fewer petals after pollination. Our results indicate that the seedling hypocotyls elongation assay may be used to identify geranium cultivars with reduced sensitivity to ethylene. The data also suggest that genetic variability exists among geraniums for both ethylene sensitivity and biosynthesis.
E-mail Discussion List is Rated Equal to Fact Sheets and Bulletins in Educational Value
Authors: Meyer Mary Hockenberry , Banks Warren
Published: December 2018

A survey of e-mail discussion list participants found 84% rated the program as a valuable or very valuable educational tool. Most participants, 82%, thought it was equal to or more valuable than printed materials such as fact sheets or bulletins. Participants cite advantages as rapid response, unique, specific information not found in other sources, and a sense of connectedness to the Master Gardener program. Disadvantages include too much e-mail, frustration with participants who do not look up easy traditional questions, chitchat, and nonhorticultural postings. A summary of messages by subject shows tree and shrub questions are asked most often.
Georgia Homeowner Survey of Landscape Management Practices
Authors: Varlamoff S. , Florkowski W.J. , Jordan J.L. , Latimer J. , Braman K.
Published: December 2018

A survey of Georgia homeowners provided insights about their use of fertilizers and pesticides. Knowledge of current homeowner practices is needed to develop a best management practices manual to be used by Master Gardeners to train the general public through the existing outreach programs. The objective of the training program is to reduce nutrient runoff and garden chemicals and improve the quality of surface water in urban water-sheds. Results showed three of four homeowners did their own landscaping and, therefore, fully controlled the amount of applied chemicals and the area of application. Fertilizers were primarily applied to lawns, but a high percentage of homeowners also applied them to trees, shrubs, and flowers. Insecticides were applied by a larger percentage of homeowners than herbicides. Control of fire ants (Solenopsis invicta) was likely the reason behind the frequent use of insecticides. The desire for a weed free lawn was the plausible motivation behind the use of herbicides, which were used mostly on lawns. Fungicide use was infrequently reported by Georgia homeowners. The pattern of fertilizer and pesticide use suggests that the developed manual should emphasize techniques and cultural practices, which could lower the dependence on chemicals, while ultimately assuring the desired appearance of turf and ornamental plants.
Effect of Different Fruit-thinning Patterns on Crop Efficiency and Fruit Quality for Greenhouse-forced `May Glo' Nectarine Trees
Authors: Caruso T. , Inglese P. , Di Vaio C. , Pace L.S.
Published: December 2018

Fruit thinning is the most effective tool in regulating fruit growth potential for early-ripening peach and nectarine (Prunus persica) cultivars, and the common strategy is to space fruit 25 to 30 cm (9.8 to 11.8 inches) throughout the canopy, while scarce attention to the canopy environment in which the fruit develops. It is likely that different light environments within the canopy require different thinning patterns and to test this hypothesis, an experiment was set up to evaluate various fruit thinning patterns (fruit densities) in relation to fruit location within the canopy of early-ripening `May Glo' nectarine trees trained to Y-shape. Differentiated fruit thinning resulted in higher yield efficiency due to a higher fruit number and average fruit weight. Differentiated thinning hastened fruit harvest and shortened the harvest period. Differentiated thinning reduced fruit variability within the tree in terms of size and soluble solids content, resulting in a higher crop value.
Irrigation Systems and Fertilizer Affect Petunia Growth
Authors: Klock-Moore Kimberly A. , Broschat Timothy K.
Published: December 2018

Two experiments were conducted to compare the growth of `Ultra White' petunia (Petunia ×hybrida) plants in a subirrigation system versus in a hand-watered system. In Expt. 1, petunia plants were watered with 50, 100, or 150 ppm (mg·L-1) of N of Peter's 20-10-20 (20N-4.4P-16.6K) and in Expt. 2, Nutricote 13-13-13 (13N-5.8P-10.8K) type 100, a controlled release fertilizer, was incorporated into the growing substrate, prior to transplanting, at rates of 3, 6, or 9 lb/yard3 (1.8, 3.6, or 4.5 kg·m-3). In both experiments, there was no difference in petunia shoot dry mass or final flower number between the irrigation systems at the lowest fertilization rate but differences were evident at the higher fertilization rates. In Expt. 1, shoot dry mass and flower number of subirrigated petunia plants fertilized with 100 ppm of N was greater than for hand-watered plants fertilized at the same rate. However, subirrigated petunia plants fertilized with 150 ppm of N were smaller with fewer flowers than hand-watered petunia plants fertilized with 150 ppm of N. Substrate electrical conductivity (EC) concentrations for petunia plants subirrigated with 150 ppm of N were 4.9 times greater than concentrations in pots hand-watered with 150 ppm of N. In Expt. 2, subirrigated petunia plants fertilized with 6 and 9 lb/yard3 were larger with more flowers than hand-watered plants fertilized at the same rates. Although substrate EC concentrations were greater in subirrigated substrates than in hand-watered substrates, substrate EC concentrations of all hand-watered plants were about 0.35 dS·m-1. Subirrigation benches similar to those used in these experiments, appear to be a viable method for growing `Ultra White' petunia plants. However, the use of Peter's 20-10-20 at concentrations greater than 100 ppm of N with subirrigation appeared to be detrimental to petunia growth probably because of high EC concentrations in the substrate. On the other hand, the use of subirrigation with Nutricote 13-13-13 type 100 incorporated at all of the rates tested did not appear to be detrimental to petunia growth.
A Profile of Juvenile Offenders in a Vocational Horticulture Curriculum
Authors: McGuinn Catherine , Relf Paula Diane
Published: December 2018

This study provides a profile of six juvenile offenders' responses to a vocational horticulture curriculum. The results indicate that vocational horticulture curricula may be a tool to strengthen a delinquent individual's bonds with society and, subsequently, evoke changes in attitudes about personal success and perceptions of personal job preparedness. The youths in this study increased their social bonds in all six categories addressed by the pretest and posttests, and were motivated to think more practically about their careers. Due to the limitations on size and scope of the study, it is exploratory in nature and provides ideas for future research and possible assessment methods for further research.
Effects of Flutolanil Fungicide and Primer Wetting Agent on Water-repellent Soil
Authors: Karnok Keith J. , Tucker Kevin A.
Published: December 2018

Localized dry spot (LDS) caused by water repellent soil is a common problem on golf course putting greens having a predominately sand root zone. Fairy ring often causes LDS by developing hydrophobic soil. Although the fungicide flutolanil is labeled for the control of fairy ring, golf course superintendents often apply flutolanil to all LDS caused by hydrophobic soil and other conditions. The objective of this study was to determine the effect of flutolanil on an existing hydrophobic soil. The study was conducted on a creeping bentgrass [Agrostis palustris (synonym A. stolonifera)] experimental golf green in which the top 4 inches (10.2 cm) of the root zone was a moderately hydrophobic sand. Six treatments were used: uncored, cored, flutolanil (two applications.), flutolanil + Primer wetting agent (two applications.), Primer (two applications.) and Primer (three applications.). Plots receiving the fungicide and wetting agent treatments were cored before application. Each treatment containing the wetting agent significantly reduced soil water repellency. Flutolanil without wetting agent had no effect on soil hydrophobicity.
Ohio State University Extension Nursery, Landscape, and Turf Team: Teamwork at Its Best
Authors: Gao Gary Y. , Chatfield James A. , Draper Erik A. , Boggs Joseph F.
Published: December 2018

The Ohio State University (OSU) Extension Nursery, Landscape, and Turf Team (ENLTT) is an innovative and interdisciplinary team comprised of extension agents, extension specialists, researchers, teaching faculty, university arboretum staff, and research assistants. ENLTT has greatly improved the process of acquisition, delivery, and support of accurate, practical, and timely educational resources through interdisciplinary and industry partnerships. The award-winning weekly electronic newsletter Buckeye Yard and Garden Line (BYGL) has been the focal point of our teamwork since 1993. An ornamental research circular, authored and edited by ENLTT members, remains the most requested publication from the Section of Communication and Technology, Ohio Agricultural Research Development Center, OSU. Strong partnership with the green industry in Ohio has resulted in the financial commitment of more than $230,000 from the Ohio Nursery and Landscape Association since 1993. ENLTT members have improved themselves as a result of educating each other through weekly BYGL conference calls from April to October, taking study tours, and conducting joint educational programs. Twenty-two commodity or issue teams, such as, Floriculture Team, Vegetable Crops Team, Tree Fruit Team, Forestry Team, Agronomic Crops Team, Sustainable Agriculture Team, and Dairy Team, have been formed in OSU Extension due to the success of ENLTT.
Horticultural and other Factors Affecting Aroma Volatile Composition of Small Fruit
Authors: Forney Charles F.
Published: December 2018

Volatile compounds are responsible for the aroma and contribute to the flavor of fresh strawberries (Fragari×anannassa), red raspberries (Rubus idaeus), and blueberries (Vaccinium sp.). Strawberry aroma is composed predominately of esters, although alcohols, ketones, and aldehydes are also present in smaller quantities. The aroma of raspberries is composed of a mixture of ketones and terpenes. In highbush blueberry (Vaccinium corymbosum), aroma is dominated by aromatic hydrocarbons, esters, terpenes and long chain alcohols, while in lowbush blueberries (Vaccinium angustifolium), aroma is predominated by esters and alcohols. The composition and concentration of these aroma compounds are affected by cultivar, fruit maturity, and storage conditions. Volatile composition varies significantly both quantitatively and qualitatively among different cultivars of small fruit. As fruit ripen, the concentration of aroma volatiles rapidly increases closely following pigment formation. In storage, volatile concentrations continue to increase but composition depends on temperature and atmosphere composition. Many opportunities exist to improve the aroma volatile composition and the resulting flavor of small fruit reaching the consumer.
Multiple Trinexapac-ethyl Applications Reduce Kentucky Bluegrass Sod Storage Temperatures
Authors: Heckman Neil L. , Gaussoin Roch E. , Horst Garald L.
Published: December 2018

Sod heating during storage can limit the distance sod may be shipped. Two experiments were conducted to determine the effect of multiple preharvest applications of trinexapac-ethyl [4-cyclopropyl-α-hydroxy-methylene)-3,5-dioxocyclohexanecarboxylic acid methyl ester] at 0.23 kg·ha-1 (0.21 lb/acre) on kentucky bluegrass (Poa pratensis) sod temperatures during the first 24 h of storage. Experimental design was completely randomized with three replications and a 2 (trinexapac-ethyl verses control) × 3 (8-h storage intervals) factorial arrangement of treatments. Trinexapac-ethyl treatments were applied 6 and 2 weeks before harvest in the first experiment and 10, 6, and 2 weeks before harvest in the second experiment. Two and three applications of trinexapac-ethyl reduced sod storage temperatures. The reduction in rate of heating in treated sod became significantly different than untreated sod within 4 h after harvest. Mean sod temperatures in both experiments were 3 °C (6 °F) cooler in treated sod after 12 h of storage than untreated sod. These results suggest that trinexapac-ethyl could be used by sod growers to extend storage times and increase shipping and market areas. A multiple application program can enable sod growers to maximize the enhancement effects of trinexapacethyl on sod storage life.
Rapid Equilibration of Leaf and Stem Water Potential under Field Conditions in Almonds, Walnuts, and Prunes
Authors: Fulton Allan , Buchner Richard , Gilles Cyndi , Olson Bill , Bertagna Nick , Walton Jed , Schwankl Larry , Shackel Ken
Published: December 2018

Covering a plant leaf with a reflective, water impervious bag ensures that equilibrium is reached between the nontranspiring leaf and the stem, and appears to improve the accuracy of determining plant water status under field conditions. However, the inconvenience of covering the leaf for 1 to 2 hours before measuring stem water potential (SWP) has constrained on-farm adoption of this irrigation management technique. A second constraint has been that the requirement of midafternoon determinations limits the area that can be monitored by one person with a pressure chamber. This paper reports findings from field studies in almonds (Prunus dulcis),prunes (P. domestica), and walnuts (Juglans regia) demonstrating modified procedures to measure midday SWP, making it a more convenient and practical tool for irrigation management. For routine monitoring and irrigation scheduling, an equilibration period of 10 min or longer appears to be suitable to provide accurate SWP measurements. Based on the large sample sizes in this study, we estimate that measurement error related to equilibration time for SWP can be reduced to an acceptable level [0.05 MPa (0.5 bar)] with a sample size of about 10 leaves when using a 10-min equilibration period. Under orchard conditions where tree growth and health appears uniform, a sample of one leaf per tree and 10 trees per irrigation management unit should give an accurate mean indicator of orchard water status. Under more variable orchard conditions a larger sample size may be needed. Midmorning and midday SWP both exhibited similar seasonal patterns and responded alike to irrigation events. On some occasions, midday SWP was accurately predicted from midmorning SWP and the change in air vapor pressure deficit (VPD) from midmorning to midday, but both over- and underestimate errors [to 0.3 MPa (3.0 bar)] appeared to be associated with unusually low or high diurnal changes in VPD, respectively. Hence, direct measurement of SWP under midday conditions (about 1300 to 1500 hr) is still recommended.
Real-time Monitoring of Greenhouse Climate Control Using the Internet
Authors: Ehler Niels , Aaslyng Jesper M.
Published: December 2018

The possibility of constructing an Internet application that would enable greenhouse users to track climate and control parameters from any Internet-connected computer was investigated. By constructing a set of HTML-templates, dynamic information from the control-system databases was integrated in real-time, and was uploaded to a common net-server by automatic generation of web pages using software developed during the project. Good performance, reliability and security were obtained and the technology proved to be an efficient way of supplying a broad range of users not only with climatic data but also with results from ongoing research.
Evaluation of Carrot Cultivars for Cut and Peel Processing in Prince Edward Island, Canada, 1997-98
Authors: Sanderson K.R. , MacKinnon S.D.
Published: December 2018

Twelve carrot (Daucus carota) cultivars were evaluated at two sites in 1997 and 13 carrot cultivars were evaluated at one site in 1998 for their potential use as cut and peel carrots. The cultivars were evaluated for total yield, marketable yield and root characteristics. Yields were quite variable with the highest yielding cultivars having the shortest root length. Of the cultivars tested, `Presto' produced high marketable yields, root diameters and root weights, however, it was very short. `Indiana' produced consistent yields and stand with a good root length. `Bolero', `Presto' and Indiana' were the best performing cultivars for cut and peel production in Prince Edward Island, Canada.
Developing a Plant Clinic Database as an Educational and Predictive Tool for Master Gardener Programs
Authors: Joh Larry , Barkley David V.
Published: December 2018

The North Carolina Cooperative Extension Service's New Hanover County Center provides the Plant Disease and Insect Clinic staffed by the Horticulture Extension Agent and Master Gardener volunteers. Residents bring in samples of weeds, diseases, and insects for identification and control recommendations. After the problem is diagnosed, a record of the information is used to construct a database that includes the date, phone number, crop, diagnosis, and control for each sample submitted. Between January 1993 and December 1999, Master Gardener volunteers entered more than 4,000 entries into a searchable/sortable electronic database to identify patterns of plant disorders. The database should be a useful tool for predicting local disease and insect cycles and aiding Master Gardeners in answering questions at the clinic and over the telephone. In addition, examination of historical records and entry of data into the database are excellent learning opportunities for new Master Gardeners.
Strawberry Plant Growth Parameters and Yield among Transplants of Different Types and from Different Geographic Sources, Grown in a Plasticulture System
Authors: Fernandez Gina E. , Butler Laura M. , Louws Frank J.
Published: December 2018

Strawberry (Fragaria × ananassa) `Chandler' plants from three sources were grown in the annual hill plasticulture system during two growing seasons (1996-97 and 1997-98). These trials evaluated the yield and vegetative performance of bareroot plants from Prince Edward Island and Ontario, Canada, and plug plant tips that were rooted in North Carolina but obtained from Ontario Canada. At the end of the season, total and marketable yields and fruit weight were not different among the plant sources. In addition, plants from all three plant sources produced equivalent yields on a weekly basis. Monthly whole plant harvests revealed that plant source did not affect leaf area, root, crown, leaf, flower or fruit dry weight during most of the growing season. In addition, plant growth parameters (specific leaf area, leaf area ratio, leaf weight ratio, and root to shoot ratio) in general did not differ among plant source in any 1 month. Plant growth did show shifts in dry weight allocation and leaf area as the season progressed that were uniform among plant sources, with the majority of the growth occurring in the spring in the two months prior to harvest. This uniformity among plant sources will allow future research to emphasize plant production practices that may reduce the risk of pest and disease problems or optimize production practices favored by growers.
Effects of Cover Crops, Nitrogen, and Tillage on Sweet Corn
Authors: Cline Gary R. , Silvernail Anthony F.
Published: December 2018

Effects of tillage, inorganic N, and winter cover crops on sweet corn (Zea mays) were examined in 1994, 1995, and 1996. Tillage treatments were tillage or no tillage, and N treatments were the addition of inorganic N at 0 (N0) or 200 (N+) kg·ha-1 (0 or 179 lb/acre). Winter cover crops included hairy vetch (Vicia villosa), winter rye (Secale cereale), and a vetch/rye biculture. In the N0, rye treatment, the soil was N deficient in 1994 and highly N deficient in 1995 and 1996. When vetch shoot N content was ≥150 kg·ha-1 (134 lb/acre) (1994 and 1995), addition of inorganic N did not increase corn yields, and it only increased corn foliar N concentrations by 8%. Reductions in corn yields (29%) and foliar N concentrations (24%) occurred when vetch shoot N content was only 120 kg·ha-1 (107 lb/acre) (1996) and inorganic N was not supplied. In 1994, the vetch/rye biculture supplied sufficient N for maximum corn yields, but addition of inorganic N increased yields by more than 50% in 1995 and 1996. Under tilled conditions, the vetch N contribution to corn appeared to equal (1996) or exceed (1994 and 1995) 82 kg·ha-1 (73 lb/acre) of N supplied as ammonium nitrate, whereas a mean value of 30 kg·ha-1 (27 lb/acre) was obtained for the biculture cover crop (1995 and 1996). No significant effects of tillage on sweet corn population densities were detected following vetch, but no-tillage significantly reduced corn population densities following rye (17%) or biculture (35%) cover crops compared to tillage. No-tillage did not reduce yields from emerged seedlings (per plant basis) for any cover crops. Vetch appeared to be a satisfactory N source for sweet corn when vetch N content was ≥150 kg·ha-1, and it could be used with no-tillage without yield reductions.
Effects of Urea and Nitric Acid on Water and Medium Quality and on Response of Anthurium
Authors: Li Yuncong , Zhang Min
Published: December 2018

Excessive bicarbonate concentrations and high irrigation water pH affect the growth and appearance of nursery plants in southern Florida. A greenhouse experiment consisting of five nitrogen (N) rates of urea or nitric acid was conducted to evaluate the influence of N sources and rates in irrigation water on bicarbonate concentrations, medium pH, and growth and appearance of anthurium (Anthurium andraeanum Lind.) plants. Pot medium pH, dry weight, plant appearance and N uptake by plants were significantly affected by N rates in irrigation water amended with either liquid urea or nitric acid, but the differences between the two N sources were not significant. The optimum growth and the best appearance of anthurium were achieved when N was added to irrigation well water as either urea or nitric acid at a rate of 20 mg·L-1 (ppm) and an electrical conductivity in a range of 0.36 to 0.42 dS·m-1 Nitrogen rates at 80 and 120 mg·L-1 induced adverse plant growth because of the greater salinity of the solutions and the lower pH of the medium.
Regulation of Biochemical Plant Growth Regulators at the U.S. Environmental Protection Agency
Authors: Lake Leslie K. , Shafer Warren E. , Reilly Sheryl K. , Jones Russell S.
Published: December 2018

Plant growth regulators (PGRs) are often used in crop production for specific niche market needs. PGRs are frequently viewed as secondary business opportunities by the private sector, especially when compared to herbicide, insecticide, and/or fungicide markets. Nonetheless, PGRs are regulated by the U.S. Environmental Protection Agency (USEPA), and the additional cost of regulatory compliance as part of commercial development is significant. Of the two broad classes of pesticides regulated by the USEPA, conventional chemicals and biological pesticides (or biopesticides), many PGRs belong to the biopesticide class, specifically the biochemical category. Because of USEPA's responsibility to assure that any pesticide used in commerce will not result in unreasonable adverse effects to humans or the environment, specific data requirements have been established for product registration. Registrants must address each requirement, either by submitting relevant data or a request to waive the requirement, prior to receiving a federal registration. For biochemical PGRs, the acceptability of data or waiver requests, as well as any proposed label uses, are reviewed by the Biopesticides and Pollution Prevention Division (BPPD). The BPPD was formed in 1994 to facilitate the development of biopesticide products. Given the time and expense associated with PGR product development and commercialization, registrants should work closely with the USEPA and other stakeholders to help ensure successful product development.
New Plant Growth Regulators: High Risk Investment?
Authors: Rademacher W. , Bucci T.
Published: December 2018

Worldwide, plant growth regulators (PGRs) account for only 3% to 4% of the total sales of plant protection agents. This limited market potential, the rising costs of development and registration, and the demand for high profitability have created major constraints to the introduction of new PGRs. Conversely, PGRs have become an integral part of agricultural and horticultural practices and one might assume that the market is sufficiently lucrative to those companies active in this area. In the past decade, at least seven new PGR products have been introduced. In many cases, reduced requirements for registration have lowered the financial risks relative to expected profits.
Development of New Plant Growth Regulators from a University Perspective
Authors: Greene Duane W.
Published: December 2018

Plant growth regulators (PGRs) play an important commercial role in horticulture. Although often expensive, they are generally used on high value crops where the costs can be retrieved through the increased value their usage creates in a given crop. The impetus for development of new PGRs is generally initiated by the agrochemical industry where they perceive a need that has a profit potential, whereas the motivation for the development of a PGR by researchers is largely to aid the industry they serve. University and government researchers initially follow a prescribed protocol early in the development process, but once they have gained personal experience with a PGR, further research is often guided by personal observations and keen technical insight. During the development and evaluation process, university and government researchers are optimistic, and negative effects are generally viewed as challenges, that can and will be overcome. Discussion and effective communication are critical components in the overall development of a new PGR. Researchers generally exchange information very freely, unless restricted from doing so by a nondisclosure or other contract agreement. The underlying goal for university and government researchers is to get approval of a new PGR product and/or use that will allow growers to produce a high quality product for consumers with an improved profit margin for growers. Development of new PGRs is undergoing major change that unfortunately will lead to the development and registration of fewer compounds. There are not as many agrochemical companies, there are a decreasing number of university and government researchers, and diminishing funds available to support the development of new PGRs.
The Apple Fruitlet Thinning Response to Carbaryl is Unaffected by Russet
Authors: Hirst Peter M.
Published: December 2018

Russet is a disorder of apple (Malus×domestica) fruit where the formation of cork cells leads to a cosmetic blemish which is commercially undesirable. One of the many causes of russet is low temperature damage early in fruit development. Following frost damage to fruit, a study was initiated to determine whether carbaryl chemical thinner was more effective in thinning russeted fruit than nonrusseted fruit. With no chemical thinner application, russeted fruit abscised at a greater rate than nonrusseted fruit. Following the application of carbaryl to the fruit however, there was no difference in the retention of fruit among the treatments. Chemically thinning with carbaryl therefore is not a technique that growers could use to preferentially thin russeted fruit.
Lime Requirement for New Jersey Blueberry-producing Soils
Authors: Heckman J.R. , Pavlis G.C. , Anastasia W.L.
Published: December 2018

In New Jersey, the major soil series (Sassafras, Pocomoke, Berryland, Atsion, and Downer) used for blueberry (Vaccinium corymbosum L.) production often have soil pH levels much lower than the soil pH range of 4.0 to 5.2 that is considered satisfactory for blueberry. The lime requirements for these soils to achieve a target soil pH of 4.8 has not been established. Soils with current soil pH levels in the range of 3.3 to 3.9 were collected from eight New Jersey sites used for blueberry production. The soils were treated with various application rates of calcium carbonate (CaCO3) and incubated in a green-house to estimate the lime requirement of each soil. After 70 days of incubation with CaCO3, results show that a general lime recommendation of 100 lb of calcium carbonate equivalent (CCE)/acre (112 kg·ha-1) for each one tenth of a soil pH unit increase desired would elevate pH of each of the soils to within a range (pH 4.3 to 5.0) that brackets the target pH of 4.8 without causing serious risk of overliming.
Seasonal Fluctuations of Leaf and Root Weight and Ginsenoside Contents of 2-, 3-, and 4-year-old American Ginseng Plants
Authors: Li Thomas S.C. , Wardle Doug
Published: December 2018

The effect of harvest period on fresh and dry leaf and root weights and ginsenoside contents of 2-, 3-, and 4-year-old american ginseng (Panax quinquefolium) plants was investigated. Ginseng plants harvested once every 4 weeks from the end of June through September had the highest and lowest fresh and dry leaf weights in June and September, respectively. The trend was reversed in roots, except for 3-year-old roots that exhibited maximum weight at the end of August. Total ginsenoside contents in leaves of 3- and 4-year-old plants increased with the growing season until the end of August, but in 2-year-old plants it increased until the end of September. Total ginsenoside contents in roots peaked at the end of June for 3- and 4-year-old plants.
Using Paclobutrazol to Control Height of Poinsettia `Freedom'
Authors: Niu Genhua , Heins Royal , Carlson Will
Published: December 2018

Late-season height control of poinsettia (Euphorbia pulcherrima) is difficult since most chemical growth retardants adversely reduce bract size when applied after first bract color. Paclobutrazol (Bonzi) controls stem elongation late in poinsettia crop development but can excessively reduce bract size if improperly applied. Two experiments were conducted to quantify how paclobutrazol application influenced height and bract area of `Freedom' poinsettia. In the first experiment, paclobutrazol was applied at 1 mg·L-1 (ppm) in 118-mL (4.0-fl oz) volumes per pot [(a.i.) 0.12 mg/pot (28,350 mg = 1.0 oz)] as a drench to a new group of plants weekly from the initiation of short days until 1 week before anthesis. Maximum reduction in height and bract area was obtained when paclobutrazol was applied immediately after short days, and the response to paclobutrazol decreased as application time was increasingly delayed toward anthesis. In the second experiment, paclobutrazol was applied weekly after first bract color as either a drench or subapplication at various concentrations. Plant height and bract area were reduced by 23% when 2 mg·L-1 [(a.i.) 0.24 mg/pot) paclobutrazol was applied through subapplication at first color. The effects of paclobutrazol on height and bract area reduction decreased as application time was progressively delayed. Concentrations lower than 1 mg·L-1 had no significant effect on height or bract area reduction, regardless of application time or method. Generally, the reduction in height and bract area was larger when paclobutrazol was applied through subapplication. The combined results from both experiments indicate that paclobutrazol drench applications after flower initiation concomitantly reduce plant height (internode extension) and bract area. Therefore, drench applications should be delayed as long as possible to limit reduction in bract size.
Effects of Paclobutrazol and Chlormequat on Growth and Flowering of Lavender
Authors: Papageorgiou I. , Giaglaras P. , Maloupa E.
Published: December 2018

Growth retardants allowed production of more uniform, compact, flowering plants for commercial use of lavender (Lavandula stoechas). Paclobutrazol at 200, 400 and 600 mg·L-1 (ppm) was sprayed in a single or double application. Chlormequat was applied at 4000, 6000 and 8000 mg·L-1 in single, double or triple spray applications repeated every 13 days. Paclobutrazol reduced lateral shoot elongation and plant height, increased the number of nodes within lateral shoots, but delayed time to anthesis. In contrast, chlormequat reduced plant height with no effect on flowering. Paclobutrazol potentially may be used commercially on lavender at rates of 200 to 400 mg·L-1 in single or double applications. The same result may be achieved with chlormequat by using 4000 to 6000 mg·L-1 in three or more applications.
Concentration by Time Product and Gas Penetration after Marine Container Fumigation of Table Grapes with Reduced Doses of Sulfur Dioxide
Authors: Crisosto Carlos H. , Palou Lluís , Garner David , Armson Donald A.
Published: December 2018

Reduced doses of sulfur dioxide (SO2) were evaluated for the fumigation of marine containers with respect to the concentration × time (CT) product and gas penetration. Two commercial export containers were loaded at 32 °F (0 °C) with 20 metric pallets [40 × 48 inches (102.5 × 123.1 cm)] comprised of 72 expanded polystyrene foam boxes (12 tiers, 6 boxes/tier) of table grapes (Vitis vinifera) and fumigated with 1.0 and 0.5 lb (0.454 and 0.227 kg) SO2, respectively. A third marine container was loaded with 20 metric pallets comprised of 84 plastic boxes of table grapes (14 tiers, 6 boxes/tier) and fumigated with 0.25 lb (0.113 kg) SO2. The boxes contained 16 lb (7.3 kg) of table grapes distributed in nine polyethylene cluster bagsenclosed in a perforated polyethylene box liner. Fumigations were performed through the bottom seal of the rear door from pre-weighed compressed SO2 cylinders. CT product was calculated after taking samples of the atmosphere in the container every 5 to 10 min and measuring the ambient SO2 concentration with a gas sampling pump and colorimetric dosimeter tubes. Pallet and box penetration of the gas was assessed by placing passive colorimetric SO2 dosimeters inside the cluster bags in boxes located in both the third and ninth center boxes from the top of pallets located in the front, center, and rear of the load. Fumigations with 1.0, 0.5, and 0.25 lb SO2, with calculated CT products at 32 °F of 925, 360, and 40 ppm-h (μL·L-1·h-1) respectively, were found to provide excessive, adequate, and insufficient SO2 doses.
NLEAP Computer Model and Multiple Linear Regression Prediction of Nitrate Leaching in Vegetable Systems
Authors: Minshew Hudson , Selker John , Hemphill Delbert , Dick Richard P.
Published: December 2018

Predicting leaching of residual soil nitrate-nitrogen (NO3-N) in wet climates is important for reducing risks of groundwater contamination and conserving soil N. The goal of this research was to determine the potential to use easily measurable or readily available soilclimatic-plant data that could be put into simple computer models and used to predict NO3 leaching under various management systems. Two computer programs were compared for their potential to predict monthly NO3-N leaching losses in western Oregon vegetable systems with or without cover crops. The models were a statistical multiple linear regression (MLR) model and the commercially available Nitrate Leaching and Economical Analysis Package model (NLEAP 1.13). The best MLR model found using stepwise regression to predict annual leachate NO3-N had four independent variables (log transformed fall soil NO3-N, leachate volume, summer crop N uptake, and N fertilizer rate) (P < 0.001, R2 = 0.57). Comparisons were made between NLEAP and field data for mass of NO3-N leached between the months of September and May from 1992 to 1997. Predictions with NLEAP showed greater correlation to observed data during high-rainfall years compared to dry or averagerainfall years. The model was found to be sensitive to yield estimates, but vegetation management choices were limiting for vegetable crops and for systems that included a cover crop.
Potato Yield Monitoring on Commercial Fields
Authors: Davenport J.R. , Redulla C.A. , Hattendorf M.J. , Evans R.G. , Boydston R.A.
Published: December 2018

An accurate yield map is imperative for successful precision farming. For 3 years (1998 to 2000) two to four potato (Solanum tuberosum) fields on a commercial farm in southeastern Washington were yield-monitored using commercial yield monitoring equipment without operator interaction. Multiple potato diggers were used to harvest the fields and diggers used were not necessarily the same at each harvest. In all years, yield monitoring data were missing due to equipment failure or lack of yield monitoring equipment on all diggers. Banding, due to dissimilar calibrations, different equipment used, or differential digger performance was observed in 1998 and 2000. Based on experience described here, some yield monitor data need minimal postprocessing or correction, other data need substantial postprocessing to make them usable, and other data may not be reliable due to equipment failure, improper calibration, or other causes. Even with preharvest calibration, it is still likely that the potato yield monitor data will need differential postprocessing, indicating that yield maps lack accuracy. In addition, comparison to yield data collected at multiple points within the field, this study found that the yield monitor over estimated potato yield. Thus, with some postprocessing, a useful yield map showing within field differences is possible. However, without significant postprocessing, the practice of using multiple diggers and yield monitors for potato harvest, both within and between fields, severely limits the ability to make consistent yield maps in commercial potato operations.
Compost Use in Commercial Citrus in Florida
Authors: Litvany Mike , Ozores-Hampton Monica
Published: December 2018

Commercial citrus (Citrus sp.) groves in Florida use an average of 150 lb/acre (168 kg·ha-1) of elemental nitrogen (N) per year. There are about 853,000 acres (345,000 ha) of commercial citrus requiring about 63,975 tons (62,652 t) of N. At an average analysis of 12% N, about 533,125 tons (483,811 t) of blended nitrogenous fertilizers are applied to citrus annually. To meet this annual N demand from compost, it would be necessary to produce 3,198,750 tons (2,901,906 t) of 2% N compost. The market for high-quality compost products in Florida is far greater than the current or projected production capacity of the state. As long as the cost benefits of compost are clear to citrus growers, demand will always exceed supply. Not all composts are equal in their nutrient availability. The best composts for use as fertilizers are derived from sewage sludge or biosolids, municipal solid waste and sludge, food waste, and/or animal manure combined with a bulking agent such as sawdust or wood chips. Composts made from wood waste as their only feedstock contain large amounts of lignin and cellulose to break down within a reasonable period to directly offset chemical fertilizers. Ultimately, they will mineralize in the soil and provide all of the benefits described earlier, but their rates of availability are in years rather than months, like the other composts.