bluuebunny/crossref_metadata_2025 huggingface dataset:
399 The Mortality of Artificially Infested Third Instar Larvas of Anastrepaha ludens and A. obliqua in Mango Fruit with Insecticidal Controlled Atmospheres at High Temperature
Authors: Yahia Elhadi M. , Ortega Dora , Moreno Pamela , Martinez Alejandro
Published: February 2019

Previous work in our laboratory and also reported in this meeting has indicated that insecticidal controlled atmospheres at high temperatures (0.5% O2 + 50% CO2 at 44-55°C and 50% RH) are very effective in causing in vitro mortality of eggs and third instar larvas of Anastrepaha ludens and A. obliqua. This work is a follow up that evaluated the effect of such atmospheres on the in vivo mortality of third instar larvas artificially infested in mango. Atmospheres evaluated included 0% O2+ 50% CO2 at 35, 37, 39, 40, 42, 43, 44, 45, 46, 47, 48, and 49°C for 160 min. Treatments at 35-40°C caused 100% mortality of larvas of A. obliqua, but not of A. ludens. Temperatures of 42 to 49°C caused 100% mortality of larvas of both species. Statistical analysis to calculate the probit 9 will be discussed.
403 Promotion of Germination and Seedling Development of Lima Beans (Phaseolus spp.) by Nickel Chloride
Authors: Broderick Cyril E.
Published: February 2019

Delaware is among the largest producers of lima beans in the United States, having more than 10,000 acres in this crop. The plants are raised from seeds, but seeds are notably prone to injury during handling. The seed has little or no endosperm and relies on reserve food materials in the cotyledons. Lima beans are legumes, and the seeds store nitrogenous compounds. Nickel is implicated in nitrogen metabolism, and nickel is now implicated as an essential mineral nutrient element. With the variable rate of germination of lima bean seeds, our objective was set to determine the effect of nickel on seedling development of the lima bean plant. Lima bean seeds were soaked for various periods in 10 solutions from 0 to 500 ppm nickel chloride. Soaking for 1 h in 100 ppm nickel chloride solution was determined to be the best treatment. The 100 ppm treatment then became the standard treatment for lima bean seeds. Hence, seeds were treated with distilled water of the 100 ppm nickel chloride. The results are that the nickel chloride significantly improved the rate of germination of lima bean seeds. Germination rates were improved from 60% ± 5% to 76% ± 3%. The total effect of treatments with nickel chloride varied from one batch of seeds to another; however, promotion of germiantion was significant. Osmoregulation and seed priming as well as stimulation of nitrogen metabolism by nickel are possible explanations of the positive effects of nickel chloride.
406 Pyruvate Decarboxylase and Alcohol Dehydrogenase Activities in Sweetpotato under Different Oxygen Atmospheres
Authors: Huang Yuehe , Picha David H. , Kilili Anthony W.
Published: February 2019

`Beauregard' sweetpotato (Ipomoea batatas L. Lam) roots were maintained under different controlled atmospheres ranging from 0% to 21% O2 at 22 °C in two separate trials for 14 days to study changes in activities of pyruvate decarboxylase (PDC) and alcohol dehydrogenase (ADH). Trial I showed no difference in activities of PDC and ADH between 0% and 1% O2, or among 2%, 5%, and 21% O2. Both PDC and ADH activities were significantly higher at 0% and 1% O2 compared to the 2%, 5%, and 21% O2 atmospheres. In trial II, both enzyme activities were lower at 1.5% O2 than at 0% O2, but higher than at 10% and 21% O2 atmospheres. The combined data of the two trials showed a very strong correlation between PDC and ADH activities (R2 = 0.86). In addition, a strong correlation existed between PDC activity and acetaldehyde concentration (R2 = 0.95). The maximal activities were at pH 6.5 for PDC and at pH 8.5 for ADH in the direction of acetaldehyde-to-ethanol. The results suggest that 1.5% O2 is the critical point for the transition from aerobic to anaerobic metabolism in CA storage of sweetpotato roots, and PDC is the key enzyme in alcoholic fermentation.
409 Controlled-Atmosphere Storage of `Shinko' and `Shinsui' Asian Pears
Authors: Park Yong Seo , Pelayo Clara , Hess-Pierce Betty , Kader Adel A.
Published: February 2019

`Shinko' and `Shinsui' Asian pears were kept in air, 2 kPa O2, 2 kPa O2 + 2.5 kPa CO2, and 2 kPa O2 + 5 kPa CO2 (balance N2 in each treatment) at 0 °C or 5 °C for up to 24 weeks. The three CA treatments reduced respiration (O2 consumption) and ethylene production rates relative to air control pears; these rates were higher at 5 °C than at 0 °C and higher for `Shinsui' than for `Shinko' pears. While `Shinsui' pears had a climacteric pattern of respiration and ethylene production rates, `Shinko' pears produced very small quantities of ethylene and exhibited a non-climacteric respiratory pattern. `Shinko' pears had a much longer postharvest life than `Shinsui' pears (24 weeks vs. 12 weeks at 0 °C). CA treatments had a greater effect on delaying deterioration of `Shinsui' than `Shinko' pears, which were more sensitive to CO2 injury and associated accumulation of fermentative metabolites (acetaldehyde, ethanol, ethyl acetate). `Shinko' pears did not benefit from CA storage and were best kept in air at 0 °C. An atmosphere of 2 kPa O2 with or without up to 5 kPa CO2 delayed flesh breakdown of `Shinsui' pears during storage 0 °C.
411 Elevated Oxygen Atmospheres as a Decay Control Alternative on Strawberry
Authors: Wszelaki Annette L. , Mitcham Elizabeth J.
Published: February 2019

Controlled atmospheres have been proven an effective postharvest disease deterrent for strawberries both in transport and storage. However, these treatments do not provide residual protection once the commodity is removed from the atmosphere, and the atmospheres can cause off-flavors in the fruit. Elevated oxygen atmospheres are a novel addition to this technology and could potentially provide better decay control without the harmful effects on fruit flavor aspects. Elevated oxygen will potentially discourage microbial growth, as anaerobes grow best under very low oxygen levels and aerobes grow best under atmospheric oxygen. Threshold elevated oxygen levels to prevent Botrytis cinerea growth in vitro and in vivo on strawberry were assessed. Botrytis cultures (mycelial plugs and spores) and fresh strawberry fruit were exposed to 21%, 40%, 60%, and 80% oxygen atmospheres at 5 °C for 5, 7, and 14 d. Growth of cultures from mycelial plugs was evaluated after treatment and during post-treatment incubation by measuring the diameter of the fungus. Spore germination and germ tube elongation were evaluated every 24 h for 3 days after treatment by counting the number of germinated spores and measuring elongation, respectively. Strawberry quality including firmness, color, soluble solids, titratable acidity, ethylene production and respiration rates, and presence of defects were evaluated upon removal from the elevated oxygen atmospheres as well as after 1, 3, and 5 d storage in air at 20 °C simulating market conditions.
413 Investigation of Nutrient Fluxes and Stem Production under Nutrient Solution Recycling and Three Levels of Nutrition in Alstroemeria
Authors: Edwards D.R. , Dixon M.A.
Published: February 2019

A concern with the greenhouse production of horticultural commodities, particularly those grown in the ground, is the difficulty in managing nutrient runoff. Alstroemeria, a heavy-feeding crop that is nearly always grown in soil, were planted into 26.5-L pots with a medium of LECA. Greenhouse experiments were designed to examine flowering stem production, quality, and nutrient flux under nutrient solution reuse (closed system) and with one of three levels of nutrition (EC of 2.1, 1.6 and 1.1 mS/cm). Plants in the closed treatments were set on troughs sloped towards separate 24-L reservoirs. The control was an open drainage system fed at 2.1 mS/cm. The reservoirs were kept at a constant volume with the addition of water after every irrigation; nutrients were added to restore the EC to demand levels. Stems were harvested twice per week and the nutrient content of the reservoirs were analyzed biweekly by ion chromatography. Data were analyzed as an RCBD with four treatments and blocks. Analysis of data from the preliminary experiment (29 May to 3 Aug. 1998) indicated number of stems and cymes were similar among treatments. Stem length, dry weight, and number of florets were depressed below the control only in lowest fed treatment. Nutrient application was reduced markedly, by up to 1000-fold in the closed vs. the open production system.
416 Blended Composts and N Rates on Growth of Potted Chrysanthemum
Authors: Ku Catherine S.M. , Bouwkamp John C.
Published: February 2019

Potted `Boaldi', `Red Akron', and `Yellow Boaldi' growth performance were evaluated in eight substrates and four N rates. The substrates included Sunshine Mix 1, Pro Gro 300S, and six compost blends. The compost feedstocks were polymer dewatered biosolids (PDB) blended with poultry litter (PL) or yard wastes (YW) and peat:perlite at final ratios of 4:2:1:1, 3:3:1:1, and 2:4:1:1. Plants received N at 75, 100, 150, or 200 mg•L-1 from 21N-2.2P-16.6K twice a week. Number of flowers, height, diameter, and grade of plants that received N at 200 mg•L-1 treatment were significant better than those received the other N treatments. For all compost blends, premium-quality plants were produced with N at 200 mg•L-1 treatment and good-quality plants were obtained with the remaining N treatments. The control substrates produced good quality plants with N treatments at 150 and 200 mg•L-1, the remaining N treatments resulted in plants that were only salable at reduced price. `Red Akron' is a free-branching spray cultivar, had more flowers and branches than the other two cultivars.
421 Commonalities of Australian Public Extension Programs
Authors: Murray Mike
Published: February 2019

A 1995/96 sabbatical leave in Australia was conducted to elucidate trends in public extension programs related to technology transfer or information delivery. Interviews with imore than 500 extension providors and users in seven states or territories were conducted. Based on these discussions, 12 commonalities or recurring themes were identified. These were the delivery of public extension programs through State Departments of Agriculture that also have regulatory responsibilities; decreased public funding for extension programs; clear separations between applied research and extension functions; adoption of purchaser/provider funding models; poor communication or collaboration between extension and universities; an emphasis on group facilitation programming; difficulties related to extension staff recruitment or retention; diminished clientele support for public extension programs; an emphasis on the sociological aspects of agricultural enterprises; the development of audio-visual educational materials; a movement to assist inefficient producers exit agriculture and; trends toward the privatization of, or cost recovery for, public extension programs.
422 Digital Video Images and Their Use in Extension Programs
Authors: Marr Charles
Published: February 2019

Digital images are becoming an essential part of computer “slide” presentations, identification of plants and problems from a distant location, and adding visual elements to Web pages. The use of digital video images allows capturing of single frames for individual or sequence photographs as well as “mass” storage of digital images. There are also some uses of short “video clips” to be included in slide or Web presentations. A discussion of digital image quality and demonstration of equipment used will be included in the presentation.
423 hortIPM: An Interactive Integrated Pest Management Program
Authors: Wilkerson Don C. , Lineberger Dan R. , Files Priscilla J.
Published: February 2019

In response to the goals set forth in Target 2000, a long-range environmental plan for the Texas/Floral Industry developed by the TAMU Nursery/Floral Management Team in cooperation with the Texas Association of Nurserymen (TAN), an interactive, World Wide Web-based integrated pest management program (hortIPM) has been developed for commercial nursery and greenhouse growers. The objective of Target 2000 is to assist growers in initiation of innovative cultural and structural practices, which will result in the following changes by the year 2000: 1) reduce water consumption to 1990 levels; 2) reduce current fertilizer and pesticide usage by 50%; 3) lower current energy consumption by 25%; 4) reduce current solid wastes from agricultural plastics by 75%; 5) develop applications for municipal wastes and composted materials for nursery and floral crop production. More so than in any other cropping system, ornamental stock producers apply pesticides on a calendar basis regardless of pest damage to prevent cosmetic injury to their crops, thus reducing their marketability. As justification for this misuse of insecticides, growers cite the extraordinary low damage thresholds associated with their crops. Nursery and floral crops producers that have better access to educational resources and recommendations may be more inclined to follow biologically sound pest management principles. HortIPM is designed as a tool to facilitate access to pest management information and enhance IPM programs already in place. Currently, hortIPM is in the developmental phase, on the cusp of release to a number of sites for preliminary evaluation.
425 Use of Geographic Information System (GIS) to Document Plant Populations for Germplasm Collections
Authors: Balch Sandra A. , McKenney Cynthia B. , Auld Dick L.
Published: February 2019

Geographically referenced information is an important aspect in the collection of wild plant species. It provides detailed information about the collection site as well as a method of relocating plant populations. In one project, native plants were collected and analyzed for the presence of gamma-linolenic acid, a valuable fatty acid used in medicinal products. In a second project, native wild-flowers were collected and evaluated for potential use as drought-tolerant ornamental landscape plants. All native plants were initially tagged in the spring while in bloom. Each collection site was revisited later for seed collection. Due to a lack of landmarks in the collection area, a GeoExplorer Global Positioning System (GPS) unit was used to capture coordinate data of latitude, longitude, and altitude. This was added to the passport file of each collection site. Differential correction was used to increase accuracy of GPS data to within a range of 10 m. ARC/INFO software was used to assemble, store, and display collection data in map form. This method has been used to document over 300 accessions and identify areas with a high frequency of plants possessing desired characteristics.
426 Modeling a Flood-Freeze Situation of a Cranberry Bog using Finite Element Analysis
Authors: Altwies James R. , Ann Workmaster Beth , Altwies Joy E. , Palta Jiwan , Roper Teryl R.
Published: February 2019

It is commonplace in Wisconsin for cranberry growers to flood their beds to form thick ice during winter to protect the uprights from dangerously low winter air temperatures. However, the specifics of ice thickness and zone temperature within and below the ice vs. surface air temperature have not been studied. We have developed several models using finite element analysis, a process by which a complex system is divided into finite segments and analyzed individually. All pieces are then recombined into the complete system so a comprehensive picture of the activity of the freezing cranberry bed may be visualized. It was determined that cold surface air temperatures of -25 °C and thin ice of 15 cm, soil and gap air temperatures do not drop lower then -5 °C, which is congruent with data collected from the field. Models on sand beds and peat beds did not show enough difference to be of concern. Temperatures within the ice, where the uprights would be encased, reached -15 °C under the cold air regime, which has been proven to be well within the survival range of the dormant buds.
429 Production of Fresh Baby Corn
Authors: Miles C.A.
Published: February 2019

Fresh baby corn is an ideal niche market crop. It is easy to produce and is growing in popularity in the U.S. In 1997 and 1998, we tested 10 corn varieties to determine suitability for fresh baby-corn production in western Washington. By harvesting ears 1 to 3 days after silk emergence, baby corn can be produced from many common sweet corn varieties, including `Kandy King', `Bodacious', `Tendertreat', and `Custer'. Ear quality characteristics such as length, width, and kernel size and appearance of these common sweet corn varieties were as good as for the variety Baby Corn, a specialty variety produced exclusively for baby corn. The corn variety GH2283, produced in the U.S. for sale of seed to Asia for baby-corn production, produced the best-quality baby corn ears in our trial. Using an in-row spacing of 2 inches, ears of baby corn can be harvested for 4 to 6 weeks, depending on variety, from a single planting. Market criteria for baby corn are 2 to 4 inches long and 1/3 to 2/3 inch in diameter at the butt end. Delaying harvest of sweet corn varieties for 3 days resulted in ears that were too large for baby corn. Field corn varieties in this trial required close monitoring to meet size criteria and delaying harvest 1 to 2 days resulted in ears that were too large. Harvest of baby corn is all by hand and height of the ear on the plant significantly affects ease of harvest, where dwarf varieties are the least easy to harvest.
434 Using Distance Technology: Inter-institutional Development and Delivery of a Course in Plant Nutrition
Authors: Williams Kim , Paparozzi Ellen T. , Maranville Jerry
Published: February 2019

As universities are required to “right-size,” faculty resources of time and expertise are strained as the institution must cater to undergraduate students while providing a complete graduate curriculum. Thus, many institutions are offering more team taught courses. For a new upper-level undergraduate and lower-level graduate course offering in Plant Nutrition and Nutrient Management, the team consists of faculty from two institutions who each bring different expertise into the classroom. The course utilized weekly chat room discussions to bring students into contact with experts from around the United States and the world. Two-way compressed video was used to allow for synchronous lecture delivery and discussion across sites. A Web site was created to facilitate student interaction and provide chat room access. Multiple student evaluations were conducted to separate learning objectives with the effectiveness of using technology. A flow-chart will be presented which details the steps and problems/accomplishments encountered in successfully delivering this course via distance technologies, including: funding procurement, determining technological compatibility across institutions, delineation of course content, Web page development, and course evaluations.
444 Changes in Quality and Maturity of Late-season Peaches (cvs. O'Henry and Nos 21) during Maturation and Ripening
Authors: Reginato G.H. , Luchsinger L.E.
Published: February 2019

Our objectives were to characterize the quality and maturity changes of peach [Prunus persica (L.) Batsch.] fruit cvs. O'Henry and Nos 21 during maturation and ripening and to identify harvest maturity indices by relating nondestructive and destructive variables. After fruit set, 400 fruit of similar diameter and tree position were tagged to follow maturation and ripening on the tree. During commercial harvest, 48 fruit were ramdomly harvested every 4 to 6 days. Ethylene evolution rate (EER) at 20 °C, fresh weight, and peel ground and cover color (L*, a*, b*, C* and Hue value) were measured to all 48 fruit. Flesh color, firmness at several fruit points, soluble solids (SS), pH, titratable acidity (TA), and SS/TA ratio were measured only to 24 fruit, and the rest were held for up to 7 days at 20 °C as a ripening period to measure the same characteristics previously mentioned. Pearson correlation coefficients were determined between variables to explore possible harvest maturity indices. The most significant changes occurred in EER and ground color (a* value) for both varieties and fresh weight only for cv. O'Henry. For `O'Henry' peaches the highest correlation (P < 0.001) was obtained between EER-suture firmness (r = -0.61). For cv. Nos 21 the highest correlation was between EER-shoulder firmness (r = -0.69). It was also found that fruit softening occurred mainly in the fruit shoulder for both cultivars. Therefore, no harvest maturity indices could be established for these cultivars.
446 Long-term Evaluation of Susceptibility of Selected Prairie Species to the Root Lesion Nematode Pratylenchus penetrans
Authors: McKeown A.W. , Potter J.W. , Gartshore M. , Carson P.
Published: February 2019

Because of the need to find plants that suppress root lesion nematodes for use in rotation or cover-crops, 16 native sand-prairie species were evaluated for host status for 6 years. Plants were grown on a Fox sand soil at a local prairie plant nursery. Soil cores were taken in the spring, summer, and fall and assayed for plant parasitic nematodes. Five species supported very low numbers (less than 100/kg soil) of root lesion nematodes. Brown-eyed Susan (Rudbeckia hirta) had no detectable nematodes for the duration. Switchgrass (Panicum virgatum L.) and Indiangrass (Sorghastrum nutans L., Nash) samples produced detectable nematodes on only two sampling dates over the 6 years and were statistically not different from brown-eyed Susan. Butterfly weed (Asclepias tuberosa L.) also had very low detectable nematodes as did sand dropseed [Sporobolus cryptandrus (Torr.) Gray.]. New Jersey tea (Ceanothus americanus L.), little bluestem [Schizachyrium scoparium (Michx.) Nash], and big bluestem (Andropogon gerardi Vitman) were poor hosts with <200 nematodes/kg soil. Mountain mint (Pycnanthemum virginianum L), wild bergamont (Monarda fistulosa L), horsemint (Monarda punctata L), and dwarf blazing star (Liatris cylindracea L) all had root lesion populations over 3000/kg soil. Horsemint and wild bergamont plants died out, possibly as a result of nematode infestation. Root lesion nematodes have an extremely wide host range in current agronomic and horticultural crops, and weeds and are difficult to manage using nonchemical means. Indiangrass, switchgrass, big bluestem, and little bluestem have all been used agriculturally for pastures and consequently have potential as beneficial long-term rotation crops for nematode management and soil building.
449 Conservation Tillage Row Crop Production in California
Authors: Mitchell J.P. , Lanini W.T. , Temple S.R. , Herrero E.V. , Miyao E.M. , Brostrom P. , Morse R. , Thomas F.
Published: February 2019

Conservation tillage (CT) row crop production is currently not widely adopted in California. Recently, however, interest in evaluating the potential of CT systems to reduce production costs and improve soil quality is growing in many areas in the state. In 1997 and 1998, we evaluated four cover crop mulches (rye/vetch, triticale/vetch, Sava medic, and Sephi medic) in a CT-transplanted tomato system relative to the conventional winter fallow (CF) practice. In both years, yields were comparable to the CF under the triticale/vetch and rye/vetch mulches. Earthworm populations after 2 years of CT production were increased 2- to 5-fold under mulches relative to the CF system. Soil carbon was increased by 16% and 6% after 2 years of CT production under the triticale/vetch and rye/vetch mulches, respectively. Weed suppression under the triticale/vetch and rye/vetch was comparable to the CF with herbicide system early in the season in both years but was maintained through harvest in only one season. Soil water storage (0-90 cm) was similar at the beginning of the tomato season in triticale/vetch, rye/vetch, and fallow plots but was higher under the mulches during much of the last 45 days of the 1998 season. Further refinement of CT practices in California's vegetable production regions is needed before wider adoption is likely.
450 Impacts of Alternative Cropping Systems on Soil Physical Properties, Crop Productivity and Quality, and Water Management in California's Sacramento Valley
Authors: Mitchell J.P. , Colla G. , Joyce B.A. , Huyck L.M. , Wallender W.W. , Temple S.R. , Brostrom P.N. , Miyao E.M. , Poudel D.
Published: February 2019

The Sustainable Agriculture Farming Systems (SAFS) Project was established in 1988 to study the transition from conventional to low-input and organic farm management in California's Sacramento Valley. We evaluated the effects of these alternative farming systems on soil compaction, water-holding capacity, infiltration, and water storage in relation to tomato yield and fruit quality within the SAFS cropping systems comparison 10 years after it had been established. Soil bulk density (0-15, 15-30, 30-45, and 45-60 cm) was not significantly different among the farming systems. In situ water-holding capacity at 24, 48 and 72 h after water application was significantly higher in the organic system at all times and depths except 45-60 cm. Cumulative water infiltration after 3 h in the organic and low-input cover crop-based plots was more than twice that of the conventional system. The more rapid infiltration in the low-input and organic systems resulted in increased total irrigation needs, more water stored in the soil profile throughout the 30 days before harvest, and lower fruit soluble solids and titratable acidity in these systems relative to the conventional system. Yields were not significantly different in the organic, low-input, and conventional systems during either 1997 or 1998.
451 Evaluating Skin-set of the Sweetpotato
Authors: Jett Lewis W.
Published: February 2019

Skinning of sweetpotatoes [Ipomoea batatas (L.) Lam] can reduce marketable yield and quality. The `Beauregard' sweetpotato, despite its consistent high yield and quality, is very susceptible to skinning injury during harvest. A research project was initiated to investigate chemical and mechanical methods to improve skinset of `Beauregard' sweetpotato. Approximately 14 days before harvest, Desicate II and Enquik (dihydrogen tetraxosulfate) were applied to the sweetpotato vines as a broadcast spray. Mechanical methods evaluated included mowing with a flail-type mower or pulling (vine detachment) 7 days before harvest. Skin-set was measured using a Halderson periderm shear tester fitted to a torquometer. The Enquik + Desicate II treatment significantly desiccated the vines relative to application of Desicate II alone. The skin set testing device was sensitive enough to detect differences between treatments. The highest skin-set reading was obtained from the pulled vine treatment. Marketable yield was not affected by application of any chemical or mechanical treatment. Curing of skinned sweetpotatoes(4 days; 30 °C; 90% relative humidity) significantly reduced postharvest moisture loss and disease incidence.
453 N Management Strategies Affect Watermelon Yield and N Leaching
Authors: Hochmuth G. , Locascio S. , Hochmuth R. , Hornsby Jennifer , Haman D. , McNeal B. , Kidder J.
Published: February 2019

Nitrate concentrations in the springs and rivers in northern Florida have been increasing, and several state agencies are interested in implementing nitrogen management programs on farms to reduce N entering the groundwater. Watermelon was grown in the first season of a six-season project under various cultural and fertilization programs to investigate the relationship of N management with N leaching. Treatments were a factorial arrangement of two cultural systems (polyethylene mulch with drip-irrigated beds and unmulched, overhead irrigated beds) and three N fertilization programs [N at the extension-recommended rate, N at the commercial-watermelon-producer rate (1.5 times recommended), or N at the recommended rate with 50% of N from poultry manure]. Nitrate in the soil beneath the watermelon crop was monitored at the 2-m depth with porous-crop suction lysimeters and soil sampling. Yields were greater with the mulch/drip irrigation system compared with the unmulched/sprinkler cultural system; however, fertilization program had no effect on yield. Nitrate-N concentrations in the soil solution at the 2-m depth with all fertilizer treatments were only slightly elevated (3 to 5 mg·L-1) above that in the unfertilized soil (< 1.0 mg·L-1) early in the season when no rain fell. Later in the season, soil solution nitrate-N concentrations at the 2-m depth increased to >50 mg·L -1 with the unmulched treatment and with the greater fertilization rate. Polyethylene mulch, drip irrigation, and recommended N rate combined to maintain groundwater nitrate-N concentration below 10 mg·L-1 for most of the production season and only slightly above 10 mg·L-1 during the summer off-season when rainfall was frequent.
454 Deficit Irrigation Affects Yield and Quality of Triploid and Diploid Watermelon
Authors: Leskovar D.I. , Perkins-Veazie P. , Meiri A.
Published: February 2019

Water conservation strategies are being investigated for watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] production in the Winter Garden region of southwest Texas. Our objective was to determine how yield and fruit quality of a triploid (cv. Summer Sweet 5244) and hybrid (cv. Summer Flavor 710) watermelon were affected by irrigation based on evapotranspiration (ET) rates and timing of application during spring. Irrigation treatments included constant 1.0 and 0.5 ET, three with varying ET before or after fruit set, and one with cycles of 1.0 and 0.5 ET. Fruit quality characteristics were measured at the unripe, ripe, and overripe maturity stages. Water deficit before or after fruit set decreased yield and fruit number. Flesh color was not affected by irrigation at any maturity stage. Soluble solid content at the ripe stage increased only in triploids irrigated with constant 0.5 ET or with 0.5 ET applied after fruit set. Triploid plants exposed to frequent cycles of water deficit set more and smaller fruit than hybrids. These data suggest that triploid watermelon types may have a different acclimation response to drought stress than diploid hybrids.
455 Response of Irrigated Potatoes to Polyolefin-coated Urea
Authors: Zvomuya Francis , Rosen Carl J.
Published: February 2019

Polyolefin-coated fertilizers are slow-release fertilizers coated with thermoplastic resins that have a temperature-dependent nutrient release pattern. A field study was conducted on a Hubbard loamy sand during 1997 and 1998 at Becker, Minn., to evaluate the effect of polyolefin-coated urea (POCU) fertilizers (Meister, Chisso Co., Japan) on yield and quality of irrigated `Russet Burbank' potatoes (Solanum tuberosum L.). The coated fertilizers were POCU-50 and POCU-70, which release 80% of their N in 50 and 70 days, respectively, at 25 °C, and a 1 POCU-50: 1POCU-70 mixture. The study compared three soluble urea treatments (N at 0, 140, and 280 kg·ha-1) split-applied at planting, emergence, and hilling vs. the same N rates of coated urea fertilizers applied in a band at planting. In 1997, a season characterized by high leaching, total and large tuber (>168 g) yields were higher with coated urea sources than soluble urea at equivalent N rate, but the N sources gave similar yields in 1998 when leaching was minimal. In both years, doubling the rate of N as soluble or coated urea from 140 to 280 kg·ha-1 had no effect on total yield, but increased the marketable yield (tuber size). Yields were higher in 1998 compared to 1997 due to poorer tuber set in 1997. However, the percentage of large tubers was higher in 1997. Specific gravity increased slightly with N rate but did not differ with N source at equivalent N rate. Hollow heart incidence was similar among all treatments in 1997, but it increased with N rate and was similar among N sources in 1998.
456 An Automatic, Controlled Water-Table Irrigation System for Vegetable Transplant Production
Authors: Buxton J.W. , Jia Wenwei
Published: February 2019

The controlled water-table irrigation (CWT) system was evaluated for vegetable seed germination and transplant growth. The system is a modification of capillary mat irrigation except that the mat along one side extends over the edge of the bench into a narrow trough running along the side of the bench. The nutrient solution level in the trough is controlled by a liquid level controller, so it is at a fixed distance below the bench surface. The nutrient solution is drawn by capillarity from the trough upward to the bench surface and then moves by capillarity to the opposite side of the bench. The system automatically maintains a constant air: water ratio in the growing media. Seeds of broccoli, tomato, and pepper were germinated in a 96-cell plug tray and grown to transplanting stage with the CWT system. A factorial experiment consisted of two growing media combined with CWT treatments of 2 and 4 cm. Excellent germination and high-quality seedlings were produced with all treatments. No differences were observed in growth of seedlings at 2 vs. 4 cm or between the two growing media. The CWT system is capable of maintaining a constant uniform water: air ratio in all plug cells on a commercial growing bench. Nutrient solution does not run off the bench. The CWT potentially is an excellent system for the irrigation of vegetable transplants.
459 Inheritance of Alternaria Late Blight [Alternaria alternata (Fries) Keissler] Resistance in Pistachio (Pistacia vera L.) and Selection for Resistance in the Field and Greenhouse
Authors: Chao Chih-Cheng T. , Parfitt Dan E. , Michailides Themis J.
Published: February 2019

Pistachio (Pistacia vera L.) progeny from the California cultivar improvement program were evaluated at two locations for their resistance to alternaria late blight [Alternaria alternata (Fries) Keissler] from 1995 to 1997. Large differences between seedlings were observed for disease resistance. Narrow sense heritabilities were calculated from half-sib analysis of 20 open pollinated families. Heritabilities of 0.48 and 0.11 at Kearney Agricultural Center were observed in 1995 and 1997, respectively. Narrow-sense heritability estimates were 0.56 and 0.54 at the Wolfskill Experimental Orchard near Davis for 1995 and 1997, respectively. Differences among progeny families to alternaria late blight infection were highly significant and were associated with the female parents. Greenhouse inoculation experiments were not strongly correlated with field results. Fifty-eight highly resistant seedlings were identified for use in future cultivar improvement efforts.
465 Dormancy Completion—A Dual Response
Authors: Erez Amnon
Published: February 2019

Most of the works evaluating dormancy completion relies on measuring the level of budbreaking or the time needed for buds to break in forcing conditions. In all cases, the evaluation of budbreak is limited to the initial stages of bud opening in both vegetative and floral buds. Very rarely the response of the new growth is determined. It is accepted that dormancy completion of the bud is of a qualitative nature of yes or no. This reasoning led to using excised branches that can not support normally a growing bud but may support the evaluation of the emerging buds. In practice, the effect of breaking bud dormancy is far reaching and has an impact on the development after budbreaking. Growth vigor is a characteristic tied to the rate of dormancy completion in a quantitative manner. After exposure to sufficient chilling growth is rapid and vigorous. When buds are exposed to warm winters, growth is sluggish and poor. Under certain conditions, budbreak may be high, but all vegetative buds will form rosettes. Likewise with floral buds, they may break satisfactorily but will not set normal fruit especially in stone fruit species. In a recent study of bud dormancy inheritance in apricots, budbreak showed a clear dominance of the low chilling characteristic; level of vegetative vigor showed a similar effect to the high and low chilling parents. Thus, two characteristics of dormancy completion should be considered. The first is the level of budbreak and the other is the vigor of the growing vegetative buds and the functionality of the flower buds, as both are affected by the conditions that induce dormancy completion.
466 Floral Cold Acclimation in Strawberry and Sour Cherry
Authors: Owens Christopher L. , Hancock J.F. , Iezzoni A.F.
Published: February 2019

Sour cherry and strawberry are examples of two Rosaceous species that often suffer crop reductions due to spring freezes. Breeding for improved floral freezing tolerance has the potential to mitigate the susceptibility of these plants to spring frosts. In model plant systems, researchers have been able to identify genes that play a role in freezing tolerance by initially searching for mRNAs regulated in response to cold temperatures. To search for cold-responsive freezing-tolerance genes in strawberry and sour cherry, it is necessary to first define their cold acclimation response. To test the hypothesis that sour cherry and strawberry flowers have the ability to cold acclimate, blooming plants were exposed to 4 °C and 16 h light for 14 days. Sour cherry styles and strawberry receptacles from open, fully developed flowers were excised, and electrolyte leakage curves were generated over a range of subzero temperatures. The temperature at which 50% electrolyte leakage (EL50) occurred was used to compare treatments. The flowers of two strawberry cultivars were tested for the ability to cold acclimate. Non-acclimated `Chandler' receptacles had an EL50 of -2.9 °C, while non-acclimated `Honeoye' had an EL50 of -3.4 °C. Conversely, acclimated `Chandler' receptacles had an EL50 of -7.7 and acclimated `Honeoye' receptacles had an EL50 of -8.7 °C, both are significantly different from non-acclimated values (P ≤ 0.01). Additionally, sour cherry styles were collected from the field at full bloom from a mapping population of 86 individuals from the cross `Rheinische Schattenmorelle' × `Erdi Botermo' and acclimated as previously described. The EL50 of the 86 progeny ranged from approximately -2.0 to -6.0 °C.
472 Effects of Low-temperature Storage on Carbohydrate Metabolism in Potato Tubers
Authors: Blenkinsop Robert W. , Copp Leslie J. , Marangoni Alejandro G. , Yada Rickey Y.
Published: February 2019

Following exposure to low temperatures (i.e., <10 °C), potato tubers undergo low-temperature sweetening (LTS), the conversion of starch to sugars. This phenomenon is of great importance to potato chip processors because high levels of reducing sugars lead to undesirable nonenzymatic browning during potato chip frying operations. The purpose of this study was to elucidate the biochemical differences in carbohydrate metabolism between a tolerant (ND 860-2) and a sensitive (Novachip) cultivar during 4 °C storage. On chilling, there was an increase in the levels of sucrose, fructose, and glucose in both cultivars, with levels being at least 2-fold higher in the sensitive cultivar. Increased levels of ATP and NADH, along with a higher respiratory rate observed in the tolerant tubers, collectively indicate a higher metabolic rate in the LTS-tolerant cultivar. ATP- and pyrophosphate-dependent phosphofructokinase activity was similar in both cultivars. Higher levels of ethanol and lactate were also observed in ND 860-2, suggesting a greater flux of sugars via anaerobic respiration. No significant differences were observed in enzymatic activities in the oxidative pentose phosphate pathway (PPP) or in levels of NADPH, thereby suggesting that the PPP does not play a role in conferring LTS tolerance. Therefore, we propose that LTS-tolerant potatoes may maintain low tissue sugar concentrations via an overall increased metabolism, rather than differing in one specific metabolic step. This increased metabolic rate does not appear to be due to greater enzyme expression (i.e., coarse control) but, rather, to a greater overall flux of carbohydrates through glycolysis and respiration.
475 Heat Treatments Reduce Irradiation-induced Changes in Phenylpropanoid Metabolism in Grapefruit
Authors: McDonald R.E. , Miller W.R. , McCollum T.G.
Published: February 2019

Irradiation is being evaluated as a quarantine treatment of grapefruit (Citrus paradisi, Macf.), but it can cause damage to the fruit. We wanted to determine if pre-irradiation heat treatments would improve fruit tolerance to irradiation as they improve tolerance to low-temperature injury. `Marsh' grapefruit were harvested from interior and exterior canopy positions and irradiated at 0 or 1.0 kGy at a dose rate of 0.148 kGy·min-1 before storage for 4 weeks at 10 °C. Following storage, pitting of flavedo tissue was the most evident condition defect noted as a result of irradiation. Pitting was noted on 15% and 27% of irradiated interior and exterior canopy fruit, respectively, whereas there was no pitting on non-irradiated fruit. Temperature conditioning before irradiation decreased the susceptibility of fruit to damage. Pitting was 26%, 19%, and 17% when fruit were held 2 h at 20 (ambient), 38 or 42 °C, respectively. There was a marked increase in phenylalanine ammonia-lyase (PAL) activity following irradiation. Maximum activity (≈18-fold increase) was attained 24 h after irradiation. Irradiation-induced PAL activity was reduced significantly by temperature conditioning at 38 or 42 °C. Exterior canopy fruit flavedo contained higher levels of total phenols, including flavanols and coumarins, compared with interior canopy fruit. The deposition of lignin was not related to canopy position. Neither irradiation nor heat treatment had an effect on total phenols or lignin deposition. It seems that irradiation causes a stress condition in the fruit, which leads to pitting of peel tissue. Heat treatment before irradiation reduced the damaging effects of irradiation.
477 Effect of High-temperature Controlled-atmosphere Treatments for Insect Control in `Bartlett' Pear Fruit
Authors: Mitcham Elizabeth , Neven Lisa , Biasi Bill
Published: February 2019

High-temperature, controlled-atmosphere treatments were explored for disinfestation of codling moths from `Bartlett' pear fruit. Fruit were freshly harvested in 1996 and 1997 and sorted for uniformity and absence of defects. Fruit were exposed to forced-heating at 46 °C for 1, 2 and 3 h in either air or a controlled atmosphere of 1% oxygen and 15% carbon dioxide. Fruit were evaluated during ripening at 20 °C immediately after treatment (1997 only) and after 3 weeks of cold storage at -1 °C. Fruit were ripened with and without an exogenous ethylene treatment in 1997. Heat treatments, and particularly heat plus CA treatments, slowed fruit ripening, even after fruit had been stored for 3 weeks. The longer the treatment, the greater the inhibition. Fruit from longer treatments were firmer than untreated fruit after 4 days of ripening, but treatment with exogenous ethylene did not overcome the inhibition in the rate of ripening, although fruit from all treatments softened faster. The mortality of codling moths following exposure to the same treatments was also determined. With the heat plus controlled-atmosphere treatments, 100% mortality was achieved in 2.5 h with the faster heating rate used in our 1996 experiment, while it took 3 h to achieve 100% mortality with the slower heating rate.
479 Pulsing and Packing Methods to Reduce Flower Opening of Cut Lilies during Long-distance and Ambient-temperature Transport
Authors: Lee Young-Sang , Lee Yong-Sun , Kang Chang-Sung
Published: February 2019

The cut Lilium oriental hybrid `Casablanca' was pulsed with chitosan (MW = 5000–10,000), grapefruit seed extract (GFSE), GA, and sucrose and enclosed with a polyethylene (PE) film of different perforations before packing into a cardboard box. Simulated transport (ST) was conducted by storing plants at 22 °C for 3 days, and the flower opening and weight loss during ST as well as post-ST floral longevity were evaluated. Pulsing with 600 ppm chitosan effectively reduced open flower percentage and weight loss during ST by 6.5% and 36%, respectively. The same concentration of chitosan, however, slightly decreased post-ST floral longevity. Adding 8% sucrose and 100 ppm GA enhanced chitosan effects. In contrast to chitosan, 500 ppm GFSE increased flower opening during ST. Enclosing plants with perforated PE film significantly reduced weight loss during ST, but increased flower opening although no ethylene accumulation over 0.08 ppm was detected in enclosed atmosphere. The opening of flowers during ST also increased in proportion to the time delay between harvest and pulsing.
485 Helping Vegetable Growers Manage Gemini Viruses in Dade County, Florida
Authors: Lamberts Mary , Polston Jane
Published: February 2019

Florida tomato growers have been managing tomato mottle mosaic virus (TMoV), vectored by the silverleaf whitefly (Bemesia argentifolia) since 1990. Bean growers in the Dade and Palm Beach County area have tried to control bean golden mosaic virus (BGMV) since it entered the area with Hurricane Andrew in 1992. During Summer 1997, tomato yellow leaf curl virus (TYLCV) was found in summer-grown tomatoes in Dade County. In Fall 1997, tomato growers were notified of the new problem and attended a workshop discussing the rigorous control that would be needed to minimize its effects. They instituted scouting and roguing programs in conjunction with appropriate pest management procedures. Dade bean growers worked with the Florida Fruit & Vegetable Assn. to obtain a Section 18 for imidacloprid. Bean and tomato growers learned about gemini viruses affecting both crops and the distribution of these viruses in the Americas in the fall of 1998. Bean growers have also learned how to use imidacloprid in late 1998/early 1999. Extension methods used and their success will also be discussed.
488 Effect of Oat Extract on Pea Root Rot Pathogen Aphanomyces euteiches
Authors: Chandler M.A. , Fritz V.A. , Pfleger F.L. , Allmaras R.R.
Published: February 2019

Pea root rot is a serious economic threat to pea production in the Great Lakes region. The primary causal organism is Aphanomyces euteiches Drechs., which is responsible for an estimated 10% annual crop loss. A fall oat (Avena sativa) rotation before spring pea planting reduces disease severity. To better understand the beneficial effect of oat on A. euteiches, isolated individual pathogen lifecycle stages of zoospores, mycelium, and oospores were treated in culture with oat extract. Resulting mycelial mats were dried and weighed. Treatment with 90%, 70%, 50%, and 30% oat extract resulted in significant spore germination and mycelial growth of A. euteiches. In the presence of nutrient solution, oat extract concentrations of 90%, 70%, 50%, and 30% significantly enhanced spore germination and mycelial growth of the pathogen. These results demonstrate that the use of oat extract results in dosage dependent germination and growth of A. euteiches.