bluuebunny/crossref_metadata_2025 huggingface dataset:
518 Regulating Fruit Set and Maturity of `Macoun' Apples
Authors: Schupp J.R.
Published: February 2019

`Macoun' is a high-value apple cultivar in the northeastern United States that is very difficult to produce. It is difficult to thin and prone to alternate bearing. `Macoun' is also prone to preharvest drop. Small fruit size, bruising, and lack of red color are additional obstacles to profitable production. The objective of this study was to compare the efficacy of two chemical thinning treatments—accel plus carbaryl, or NAA plus carbaryl—with an untreated control. A second objective was to evaluate the efficacy of ReTain for delaying `Macoun' fruit maturity and to determine if there was an interaction between ReTain and thinning treatment on fruit characteristics at harvest. Both thinning treatments were effective in reducing fruit set in 1997. Accel plus carbaryl was effective again in 1998, while NAA plus carbaryl over-thinned. Accel increased fruit size in 1997 compared to unthinned controls, and both thinning treatments increased fruit size in 1998. Accel increased fruit firmness in both years. ReTain reduced preharvest drop and delayed fruit maturity both years. In 1997, firmness was greatest for fruit treated with accel and ReTain, while ReTain had no effect on firmness of fruit from NAA thinned trees. ReTain had no effect on fruit firmness in 1998.
519 The Negative Impact of Sevin XLR Plus Thinner Use on Apple Fruit Quality under Certain Environmental Conditions
Authors: Unrath C.R.
Published: February 2019

The use of Sevin XLR Plus in chemical thinning applications at or shortly after petal fall in 1998 resulted in serious negative fruit quality effect, especially on `Red Delicious'. This negative fruit quality impact was worse in certain Henderson Co., N.C., orchards. Fruit diameter was reduced by 9%, fruit weight was reduced by 22%, misshapen fruit increased by 30%, eliminator fruit (<2.25″) increased by 102%, severely stunted fruit (<2.0″) increased by 317%. Surface russetting increased by 160% and seed numbers per fruit dropped by 27%. These are “never before seen” fruit quality problems for North Caronlina, which appear to be related to the unusual environmental conditions between full bloom and fruit thinning. Comparing the 30-year weather records, Apr. 1998 was the wettest April on record with twice the average rainfall. There were only two rain free days between bloom and petal fall, and only 9 of the 30 days following bloom were rain-free. Daily lows were at or above while daily highs were below the 30-year average, resulting in an extremely small daily temperature fluctuation. The departure from normal for average daily temperature was highly negative from partial petal fall until 2 weeks post petal fall. Daily relative humidity values for daily minimum, average and maximum were consistently and substantially above 30-year average values. It appears that these environmental extremes with Sevin XLR Plus use has an impact on fruit quality. In one `Golden Delicious' orchard where Sevin formulations could be compared side by side, fruit russetting jumped from 5.3% with 50 WP to 36.2% with the XLR Plus formulation.
520 Methyl Jasmonate Causes Ethylene Production and Abscission in Citrus
Authors: Burns J.K. , Hartmond U. , Yuan R. , Kender W.J.
Published: February 2019

Methyl jasmonate (Me-Ja) is a naturally occurring ubiquitous compound in plants. Me-Ja is considered to be a putative plant hormone because of its effect on plant processes such as senescence, germination, tuber formation, signal transduction, ethylene production, and abscission at low exogenous concentrations. We applied Me-Ja to fruit or whole trees of `Hamlin' or `Valencia' orange to determine the potential of this compound as a mature fruit abscission agent. Me-Ja (0, 1, 5, 10, or 20 mM in 0.1% Kinetic adjuvant) was applied to whole trees with a handgun or boom sprayer rates of 4850 and 1790 L·ha–1, respectively. Alternatively, tree fruit were dipped in Me-Ja solutions. Fruit drop, leaf drop and ethylene production in both fruit and leaves and fruit detachment force in fruit were monitored at various times up to 2 weeks after application. Me-Ja treatment resulted in increased ethylene production in fruit and leaves 1 to 2 days after application. Fruit detachment force significantly declined 6 to 10 days after application followed by significant fruit drop. Applications of Me-Ja >10 mM resulted in an unacceptable amount of canopy defoliation. The results suggest that Me-Ja has potential as an abscission agent for citrus. Future work will focus on improving uniformity of application and response.
550 A Naturally Occurring Compound for Controlling Powdery Mildew of Greenhouse Roses
Authors: Newman Steven E. , Roll Michael J. , Harkrader Ronald J.
Published: February 2019

Quaternary benzophenanthridine alkaloids (QBAs) isolated from plants in the family Papaveraceae are effective for the control of some fungal diseases. Extracts from Macleaya cordata, a species rich in QBAs, were formulated at 150 mg·L–1 QBA for spray application to greenhouse roses infected with Sphaerotheca pannosa var. rosae (powdery mildew). The QBA formulation was applied at 10-day intervals. For comparison, copper sulfate pentahydrate, piperalin, and fenarimol also were applied to mildew-infected plants within the same greenhouse at their respective labeled rates. One day after treatment, visible symptoms of mildew infection were reduced 60% by QBA, whereas fenarimol, copper sulfate pentahydrate, and piperalin reduced the symptoms of infection 50%, 75%, and 85%, respectively. Subsequent studies demonstrated that a tank mix of QBA and piperalin provided enhanced control of powdery mildew on rose. Results from this study indicate that QBAs have the potential to be developed as a biorational fungicide for greenhouse use with both fungicidal and fungistatic activity.
556 Influence of Supplemental Calcium Fertilization on Potato Tuber Size and Tuber Number
Authors: Ozgen Senay , Ozgen Mustafa , Palta Jiwan P.
Published: February 2019

Several recent studies, including from our laboratory, have provided evidence that by improving tuber calcium level, we can improve tuber quality such as low internal defects and better storability. The purpose of this study was to be determine the influence of supplemental calcium fertilization on tuber size and tuber number. For this purpose, plantlets of Solanum tuberosum cv. Russet Burbank raised in tissue culture were planted in 20-L pots filled with sandy loam soil with pH of 6.9 and soil calcium level of 350 ppm. All treatments received same total amount of nitrogen (at the rate of 280 kg·ha–1). Five treatments were evaluated: i) nonsplit nitrogen (from ammonium nitrate), ii) split nitrogen (from ammonium nitrate), iii) split nitrogen + gypsum, iv) split nitrogen (from liquid nitrogen) + calcium chloride, and v) split nitrogen (from calcium nitrate). The total calcium was applied at the rate of 168 kg·ha–1. Gypsum application was made at 4 weeks after planting, and other sources of calcium were applied on a split schedule (equally split at 4, 6, 8 weeks after planting). Four months after planting, tubers were harvested and evaluated. In general, all calcium treatments had lower tuber number and greater tuber size compared to the nonsplit nitrogen control. The percentage of total A-grade tubers as well as the percentage yield from A-grade tubers was increased by all calcium applications. These results suggest that calcium content I the soil can influence both potato tuber number and tuber size.
561 Using AFLPs to Examine Genetic Diversity in Umbrella Fern
Authors: Keiper F.J. , McConchie R.
Published: February 2019

Umbrella fern [Sticherus flabellatus (R. Br.) St John] is a successful Australian native foliage product. Currently, all umbrella fern sold on the market is bush-harvested. To meet the growing demand for this product on local and international markets, a commercially viable method for its production must be developed, with effective management of the germplasm resource in terms of conservation and exploitation. To manage this resource, breeders require a detailed knowledge of the amount and distribution of genetic variability within the species. Traditionally, plant breeders focus on a combination of agronomic and morphological traits (phenotype) to measure genetic diversity. In umbrella fern there are a limited number of morphological traits, and these are influenced by environmental factors and therefore do not reflect true genetic diversity. To overcome these problems, molecular techniques such as PCR-based DNA markers are used to complement traditional strategies for genotype assessment. DNA markers have the advantages of being independent of environmental effects, as well as being fast, cost-effective, reproducible, and largely accessible to the nonmolecular geneticist. Amplified fragment length polymorphisms (AFLPs) fulfil many of the desirable features of molecular markers, as well as requiring little knowledge of the genome to be investigated. AFLPs have been used widely in the analysis of breeding systems, ecogeographical variation, and genetic variation within and between natural populations. To date there are no published accounts of DNA molecular marker research on umbrella fern. A DNA extraction protocol has been developed for this species, and AFLP markers have been used to analyse genetic diversity within and between natural populations sampled in the Sydney Basin. A large number of polymorphic loci were revealed using 11 primer combinations. The genetic variation detected was partitioned between rather than within populations, suggesting that the mating system in Sticherus is primarily inbreeding. Data will be presented illustrating AFLPs as useful molecular markers for assessing genetic diversity within and between populations of umbrella fern and providing insight on the breeding system used by the species.
563 Influence of Ultra-high Levels of Carbon Dioxide on Secondary Metabolite Production in Vitro
Authors: Tisserat Brent , Vaughn Steven
Published: February 2019

The influence of a wide range of CO2 levels on the growth, morphogenesis, and secondary metabolite production in vitro was evaluated. Shoots of thyme (Thymus vulgaris L.) and a spearmint–peppermint cross (Mentha spicata × Mentha piperita) were grown on MS medium with and without 3% sucrose under 350, 1500, 3000, 10,000, and 30,000 μL CO2/L for 8 weeks. Dichloromethane extracts from leafs were analyzed using GC-MS techniques. Prominent peaks were identified by comparison with known standards. Highest growth (i.e., fresh weight) and morphogenesis responses (i.e., leafs, shoots and roots) were obtained when shoots were grown under 10,000 μL CO2/L regardless of whether or not sucrose was included in the medium. Ultra-high CO2 concentrations (3000 μL CO2/L) stimulated secondary metabolite production regardless of whether or not the medium contained sucrose. However, the combination of certain ultra-high CO2 levels (e.g., 3000 to 10,000 μL CO2/L) and the presence of sucrose in the medium resulted in shoots producing the highest levels of secondary metabolites. These results suggest that in vitro photosynthesis, which is stimulated by ultrahigh CO2 levels, may enhance secondary metabolite production.
570 The Poinsettia Stock Plant Light Environment Impacts Poinsettia Stem Breakage
Authors: Faust James E. , Korczynski Pamela
Published: February 2019

In 1998, `Freedom Red' poinsettia stock plants were grown outdoors under 0%, 60%, and 80% shade cloth. The stock plants received a single pinch leaving 10 nodes below the pinch. Cuttings were harvested once per week for 3 weeks. The cuttings were propagated, transplanted, pinched, and grown to anthesis in the same greenhouses. After anthesis, the plants were dropped onto a concrete pad from increasing heights ranging from 10 to 70 cm. Stem breakage was recorded each time the plants were dropped. Stem breakage of the finished plants increased as the percentage of shade cloth over the stock plants increased and as cutting harvest week number increased. From the Week 1 cuttings, 0%, 8%, and 10% of the lateral stems broke off of plants from the 0%, 60%, and 80% shade cloth treatments when the plants were dropped 20 cm. From Week 2 cuttings, 6%, 30%, and 36% of the lateral stems broke off the 0%, 60%, and 80% shade treatments. From Week 3 cuttings, 0%, 29%, and 43% of the lateral stems broke off of the 0%, 60%, and 80% shade treatments that were dropped 20 cm. Thirty-six percent of the Week 3 cuttings broke off of the 80% shade treatment plants before anthesis, while none of the lateral shoots broke off of the 0% shade treatment until the plants were dropped from 40 cm.
571 Effect of Photothermal Ratio on Poinsettia Plant Quality at Anthesis
Authors: Liu Bin , Heins Royal D.
Published: February 2019

Photothermal ratio (PTR) is defined as the ratio of radiant energy (light) to thermal energy (temperature). The objective of this study was to quantify the effect of PTR during the vegetative (PTRv) and reproductive phase (PTRr) on finished plant quality of `Freedom' poinsettia. In Expt. I, plants were grown under 27 combinations of three temperatures, three daily light integrals (DLI), and three plant spacings from pinch to the onset of short-day flower induction and then moved to a common PTR until anthesis. In Expt. II, plants were grown under a common PTR during the vegetative stage and then assigned to nine combinations of one temperature, three DLIs, and three plant spacings after the onset of short-day flower induction. Both PTRr and PTRv affected final plant dry weight. All components of dry weight (total, stem, green leaf, and bract) responded in a linear way to PTRr and in a quadratic way to PTRv. Stem strength was more dependent on PTRv than PTRr. When PTRv increased from 0.02 to 0.06 mol/degree-day per plant, stem diameter increased about 24% while stem strength increased 75%. The size of bracts and cyathia was linearly correlated to PTRr, but not affected by PTRv. When PTRr increased from 0.02 to 0.06 mol/degree-day per plant, bract area, inflorescence diameter, and cyathia diameter increased 45%, 23%, and 44%, respectively.
586 Studies on the Mode of Action of NH4NO3 as a Spray Additive on Penetration of 14C-NAA through Isolated Tomato Fruit Cuticle
Authors: Fader Royal G. , Ogata Tsuneo , Bukovac Martin J.
Published: February 2019

NAA, a weak organic acid plant growth regulator (pKa 4.2), penetrates the plant cuticle preferentially as an undissociated molecule (<10% dissociated at pH 3.2). We have reported, using a finite dose diffusion system, that NH4NO3 (AN, 8 mM) at pH 5.2 (>90% dissociated) enhanced the penetration of 14C-NAA through isolated tomato fruit cuticular membranes (CM). AN appears to preferentially enhance penetration of the dissociated NAA molecule over the nondissociated form. A possible mode of action is that AN affects the cuticle matrix, allowing for greater NAA penetration. Acid treatment (4 N HCl) of the cuticle, which alters the cuticle's ionic characteristics, resulted in a 10% reduction in NAA penetration from droplets in the presence of AN. When AN (80 mM) was included in the receiver solution of the diffusion cell in an effort to infuse the cuticle matrix, NAA penetration was not increased compared to when AN was present in the applied droplet. AN (8 mM) also increased NAA penetration through dewaxed tomato cuticular membranes (DCM; +252% for DCM vs. +190% for CM in 120 h). Since AN only enhances NAA penetration when included with the NAA in the treatment droplet, the AN effect may be related to the role of the droplet/deposit (droplet residue) as a donor. This conclusion is further supported with sorption studies, where AN over a 100-fold concentration range (0.8–80 mM) did not increase NAA sorption by tomato fruit CM and where no deposit is present. The role of the physicochemical nature of the deposit, including the chemical/ionic characteristics of any additive (i.e., AN) and active ingredient will be discussed.
594 Effect of Water Stress during the Harvest Period on the Carbohydrate Reserves of Mature Almond Trees
Authors: Esparza Gaston , DeJong Ted M. , Weinbaum Steve A.
Published: February 2019

The effect of water stress during the harvest period on carbohydrate reserves at the end of the growing season was studied for mature, field-grown almond trees. The following irrigation treatments were imposed during 1995, 1996, and 1997: a) full irrigation (FI) (irrigation every 3–7 days), b) moderate stress (MS) (18 days of irrigation cut-off), and c) severe stress (SS) (35, 47, and 53 days of irrigation cut-off for 1995, 1996, and 1997, respectively). Midday stem (Yms) and predawn leaf (Ypd) water potentials were monitored during each season's stress. Three trees of contrasting treatments (FI vs. SS) were excavated on 10 Dec. 1997 and divided into tree components for dry weight and TNC concentration determination. Although there was no significant difference in whole-tree biomass between the excavated FI and SS trees, total new stem growth of SS trees was half of FI trees. TNC concentrations in the organs of SS trees were significantly reduced compared to FI trees. Total calculated whole tree TNC content for SS trees was 26.1% less than FI trees. The difference in TNC content between FI and SS trees was larger for roots (34.9%) than for the aerial parts (21.1%) indicating the higher sensitivity of roots for reflecting reserve status. Although roots constituted just 13.4% of the whole tree biomass, they stored 36.4% of TNC. Only roots exhibited a clear association between the minimum values of Yms and Ypd during the season and TNC concentration of 12 non-excavated additional trees that were subsampled at the end of the growing season.
603 Cover Crop Mulches for Tomato Production in South Florida as an Alternative to Methyl Bromide
Authors: Zinati Gladis M. , Bryan Herbert H. , Klassen Waldemar , Abdul-Baki Aref A.
Published: February 2019

In the quest to produce tomatoes without using methyl bromide, cover crops including sunnhemp, cowpea, hairy vetch, and sorghum sudan were planted on calcareous gravelly soils of southern Florida in Oct. 1998. These crops, singly or in mix, were grown on raised beds for 3 months before they were mowed down with no tillage. Sorghum sudan was plowed down and covered with plastic mulch, a conventional farming practice. In addition, uncropped plots fertilized with 6 N–2.6P–10K at 0 or 1124 kg·ha–1 were either treated with or without methyl bromide-chloropicrin and plowed down. `Sanibel' tomatoes (Lycopersicon esculentum Mill) were transplanted in two plant densities (one row vs. two rows on a bed) immediately after mowing. Tomatoes were fertigated with 112 N and 186 K kg·ha–1 during the growing season. Sunnhemp biomass alone or in mix with cowpea was higher than any other treatment. Biomass of sorghum sudan and hairy vetch were lowest. Canopy coverage, nutrient content of cover crops, and their effects on tomato growth, nutrient content, and yield will be discussed.
605 Evaluation of How Cover Crop, Tillage, and N Fertilization Affect Nitrogen Sufficiency in Watermelons
Authors: Silvernail Anthony F. , Cline Gary R.
Published: February 2019

The effects of cover crop, tillage, and N fertilization on yields of `Paladin' watermelon (Citrullus lanatus) were analyzed by determining available soil N levels, foliar N content, and relative greenness with a SPAD-502 chlorophyll meter. Analyses from all three analytical procedures identified N deficiencies in watermelon with their respected measurements. Available soil N analyses indicated that soil N levels below 40 mg·kg–1 at vining caused dramatic decreases in yields, while the level needed to ensure maximal yields during the same period was 100 mg·kg–1. Results from foliar and SPAD tests indicated that plants with foliar N levels below 42 g·kg–1 and SPAD readings below 40 SPAD units at anthesis will have suppressed yields. Optimal foliar N levels and SPAD readings required for maximum yields were 50 g·kg –1 and 48 SPAD units, respectively. The main difference among all three N testing procedures was that available soil N analysis was able to detect possible deficiencies two to three weeks before either the foliar or SPAD analysis. Differences in yield between plants from conventionally tilled plots and no-till plots were not significant. However, inorganic N fertilization significantly increased yields in watermelon following both rye (Secale cereale) and mix cover crop treatments. Watermelon yields of plants following the hairy vetch (Vicia villosa) cover crop treatment showed no response to inorganic N fertilization. Of the three cover crop treatments, the addition of N fertilizer had the most effect in the rye treatment.
620 Testing Neem Leaf Extract to Control Contamination in Guava Tissue Culture
Authors: Robbins J.L. , Li X.Y. , Yadav A.K.
Published: February 2019

Shoot tip explants from field-grown guava (Psidium guajava L.) trees, which frequently show a high rate of contamination, were cultured on the MS medium with neem leaf (Azadirechta indica L.) extract in H2O. Ten grams of neem powder prepared from crushed dried leaves was made to 200 mL aqueous solution and was left on a laboratory bench for 24 h. The amber-color neem extract was filtered to separate and discard solid. The liquid was refrigerated until needed. To 950 mL basic medium in deionized H2O containing 25 mL macronutrients, 5 mL micronutrients, 5 mL vitamins, 5 mL EDTA + Fe, 2 mL BA, 30 g sucrose, and 7 g agar, 50 mL neem extract was added either before or after autoclaving. No neem extract was added to the control. Medium was adjusted to 5.7 pH. Unused medium was refrigerated. Shoot tips from actively growing young twigs of field-grown L-49 guava trees that showed variable contamination in previous studies were harvested during midmorning hours. Samples were washed in running water and disinfected with 15% Clorox solution with few drops of Tween-20 for 15 min. There were 20 explants in each treatment. Explants were subcultured a week later. None of the four test studies showed contamination-free cultures from field trees. There was no consistency due to autoclaving neem extract. The neem leaf extract did not show complete elimination of contamination, although it delayed it for few days. It was concluded that neem extract was not effective at concentrations used in getting rid of contamination. Therefore, further investigate effect of neem for this purpose higher concentrations need to be examined.
630 The Effect of Nitrogen Fertilizer Form, Concentration, and Delivery System on the Growth and Plant Quality of Poinsettia
Authors: Ferrell John , Ching Alejandro
Published: February 2019

Rooted cuttings of poinsettia (Euphorbia pulcherrima willd.ex.klotzch cv. Eckespoint Freedom Red) were grown under 16-h photoperiod in plastic pots (6 inches in diameter) containing 1 sand: 1 Metro-Mix 500 (v/v) to determine the response of nitrogen fertilizer forms, concentrations, and delivery methods on plant growth and quality. Plant height, number of lateral shoots, and number of leaves were increased with osmocote 19N–6P–12K at the rate of 4 gdm–3 compared to 100–200 ppm of calcium nitrate (foliar spray), 60–100 ppm urea (foliar spray), 80–120 ppm of ammonium sulfate (soil drench), 100–140 ppm of poinsettia 20N–5P–19K (soil drench), and 8 gdm–3 of osmocote (slow release), showing superior plant growth. Data show that delivering nitrogenous fertilizers by foliar sprays tends to reduce plant growth with short plant stems and a low number of lateral shoots and leaves compared to soil drench application, with the exception of osmocote 19N–6P–12K at a rate of 8 gdm–3. Plant quality factors such as the number of discolored or dead leaves and the degree of green coloration on the leaves were also affected by the form and delivery system of nitrogenous fertilizers.
633 Field Performance of “Transgenic” Potato, with Resistance to Colorado Potato Beetle and Viruses
Authors: Duncan David R. , Hammond David , Zalewski Jim , Cudnohufsky John , Kaniewski Wojciech , Thornton Mike , Bookout Jeffrey T. , Lavrik Paul , Rogan Glennon J. , Feldman-Riebe Jennifer
Published: February 2019

After more than 10 years of research, Monsanto scientists have developed improved seed potatoes that are protected from serious pests, including insects and disease. The first commercial products resulting from this effort were NewLeaf ® potatoes derived from `Russet Burbank' and `Atlantic' parents. The NewLeaf® product was commercialized in 1995 and contains a gene from Bacillus thuringiensis (variety tenebrionis) (B.t.t.). for the production of the Cry3A protein. Potatoes expressing this gene are completely protected from the Colorado potato beetle (CPB) and need no additional chemical protection for this insect pest. The U.S. Food and Drug Administration (FDA), U.S. Dept. of Agriculture (USDA), and U.S. Environmental Protection Agency (EPA) have all determined that these potatoes are the same in safety and nutritional composition as any other `Russet Burbank' and `Atlantic' potatoes. These potatoes have also been approved by Health Canada, Agri-Food Canada and Agriculture Canada and by Japan and Mexico for food use. Commercial growers across North America have experienced outstanding performance while growing NewLeaf® potatoes 3 years in a row. This level of performance is the result of stable, nonsignificant differences in expression of the Cry3A gene. The stable performance, also, is a result of an effective insect resistance management program based on maintaining CPB refuges near NewLeaf ® fields, reducing CPB populations, and monitoring for CPB surviving exposure to NewLeaf® potatoes. In 1998 NewLeaf Y®), conferring resistance to both CPB and potato virus Y, and NewLeaf Plus®, conferring resistance to CPB and potato leafroll virus will be commercially released.
638 The Economics of Organic Agriculture
Authors: Brumfield Robin G.
Published: February 2019

Since World War II, U.S. agriculture has reduced production costs by substituting petrochemicals for labor, often resulting in overuse of agricultural chemicals. Among the adverse results of chemical overuse are increases in certain pests, groundwater and surface water contamination, and surface water run-off. There is a growing perception that consumers bear the risk of pesticide use and farmers reap the profits. For farmers, the short-term risk of losing a crop that is already planted may take precedence over the long-term risks of such things as the pests developing resistance to pesticide, environmental damage, and applicator health risks. Alternative farming programs such as ICM and organic farming allow farmers to reconcile short-term risks and long-term benefits. Before farmers adopt an alternative system, they must be convinced that economic benefits from the alternative farming program surpass the costs incurred. Few studies have compared the cost of producing organic produce vs. using conventional production systems. One study found that net returns were slightly higher in ICM and organic systems that conventional ones. This is because of lower costs when using ICM systems and price premiums for organic crops. These results suggest that there may not be any trade-off between economic efficiency and environmentally friendly farming practices. If the society desires better environmental quality, it will be ready to pay premium price for the organic or ICM-grown vegetables. In a free-market system, farmers will use the market signals in the form of price, and they will produce accordingly.
639 Organic Alliance
Authors: Duff Barbara
Published: February 2019

Organics is the fastest growing trend in the food industry, increasing at an annual rate of more than 20% per year for the past 7 years. In the upper midwestern United States, a pilot project aimed at increasing the sales of organics in mainstream supermarkets has had an even higher success rate. We'll take a look at how this program was developed and implemented and the ways in which consumers, farmers, and grocers were educated about organic food. We'll discuss trends in organics, what consumers want, and how grocers can best promote organic products and increase their sales.
643 Site-specific Management for the 21st Century
Authors: Robert Pierre C.
Published: February 2019

The new agricultural system called soil/site specific crop management (SSCM), now more generally named precision agriculture (precision farming) is the start of a revolution in natural resource management based on INFORMATION TECHNOLOGY AND CONTROL: it is bringing agriculture in the digital and information age. New technologies in the early 80s, particularly the microprocessor, made possible the development in the United States of farm machinery computers and controllers, the electronic acquisition and process of spatial field data to build farm geographic record keeping systems, the production of soil/site specific condition and management maps using GIS, the positioning of machines using GPS, and the development of real-time soil and crop sensors, particularly yield sensors. The concept of precision agriculture originated from a better awareness of soil and crop conditions variability within fields. The variability of soil conditions within parcels in the U.S. has been demonstrated in many ways (soil survey, soil sampling, and remote sensing) for both soil nutrients and soil physical properties (e.g., available water and compaction). It is progressively found that the concept of precision agriculture can be applied to a variety of crops and practices; management technological levels; and farm types and sizes. For example, in addition to grain crops (corn, soybeans, and wheat), applications are now developed for sugar beet and sugar cane, potato, cotton, peanut, vegetables, turf, or- chard, livestock, tree plantation, etc. Precision agriculture is still in infancy but it is the agricultural system of the future because it offers a unique variety of potential benefits in profitability, productivity, sustainability, crop quality, food safety, environmental protection, on-farm quality of life, and rural economic development.
644 Precision Agriculture Technology for Horticultural Crop Production
Authors: Roberson Gary T.
Published: February 2019

Precision agriculture is a comprehensive system that relies on information, technology, and management to optimize agricultural production. While used for several years in agronomic crops, it is attracting increasing interest in horticultural crops. Relatively high per-acre crop values for some horticultural crops makes precision agriculture an attractive production system. Precision agriculture efforts in biological and agricultural engineering at North Carolina State Univ. are currently focused in two functional areas: site specific managment (SSM) and postharvest process managment (PPM). Much of the information base, technology, and management practices developed in agronomic crops have practical and potentially profitable applications in fruit and vegetable production. Mechanized soil sampling, and variable rate control systems are readily adapted to horticultural crops. Postharvest controls are widely used to enhance or protect product quality. These technologies and their applications will be discussed in this presentation. Yield monitors are under development for many crops that can be mechanically harvested. An overview of these developments will be discussed. In addition, low-cost technologies for entry into precision will be presented.
659 Reducing Floral Initiation and Return Bloom in Fruit Trees— Applications and Implications in Fruit Production: Pome Fruit
Authors: Greene Duane W.
Published: February 2019

Pome fruit display a biennial bearing tendency that is characterized by heavy flowering and fruit set one year followed by a year with reduced bloom and fruit set. This tendancy results in a year with heavy cropping with small fruit, and a subsequent year with large fruit and a small crop. Both situations are undesirable. Chemical thinners in the “on” year are frequently used to modify this cropping behavior. Alternative methods to control cropping by flower bud inhibitions will be discussed. Gibberellin application in the “off” year at or soon after bloom will inhibit flower bud formation and encourage moderate flowering. This method of crop regulation has been used infrequently. Gibberellins differ in their ability to inhibit flowering. Therefore, selection of a specific gibberellin and an effective concentration range may provide greater flexibility in controlling flowering. The cytokinins CPPU and thidiazuron inhibit flower bud formation, increase fruit size, and also thin fruit. Appropriate application of these cytokinins will be discussed where beneficial effects on fruit size may be achieved while maintaining a moderate level of flower bud formation.
663 Breeding of Woody Landscape Plants at the Univ. of Minnesota
Authors: Pellett Harold
Published: February 2019

Breeding, selection and evaluation of woody landscape plants has been an active project at the Univ. of Minnesota for many years. The goal of the project is to develop and or identify superior plants that are well adapted to the climatic conditions of Minnesota and other northern areas. About 20 cultivars of many species have been introduced to the nursery trade through this program in the past 20 years. These introductions result from selections made from populations arising from controlled crosses and from open-pollinated populations and native plant populations. One of the primary efforts has been development of the cold hardy, “lights series” of deciduous azaleas. These possess flower bud hardiness of from –35 to –40 °C. Other current breeding activities include efforts with Viburnum, Acer rubrum, Rosa, and intergeneric hybridization in the Pomoidaea subfamily of Rosaceae. An integral part of the project is development and use of techniques to screen for tolerances to various environmental stresses. Approaches used will be discussed and plants currently under evaluation will be described and illustrated with slides.
671 Impact of Southeastern Hurricanes on Peach and Pecan Orchards
Authors: Reighard Gregory , Wood Bruce , Beckman Thomas , Parker Michael , Krewer Gerard
Published: February 2019

Southeastern peach and pecan orchards weathered hurricanes in the 1980s and 1990s that left long-term effects on tree health and productivity. Pecan trees were affected the most, due to being blown down from strong winds and wet soils or suffering considerable damage to branches and immature nuts resulting in massive nut drops. Premature nut drop triggered or enhanced alternate bearing problems. Cultivar differences were evident in the ability of trees to withstand wind damage, with open-canopy trees being most resistant, but essentially all trees were damaged when they exceeded ≈17m in height. Hurricanes in older, alternate-bearing orchards sometimes broke enough limbs to induce sufficient vegetative regrowth to reestablish an equilibrium between sink (nuts) and source (foliage), thus enhancing yields in subsequent years. Peach trees which were less than 4.5 m tall and already harvested usually did not blow over unless the soil was very wet. However, peach trees were often twisted about the tree axis from the change in wind directions as the hurricane passed over. Afterwards, many trees leaned more than 30 °, especially trees less than 6 to 7 years of age. Root damage was significant and increased when trees were manually repositioned as additional root breakage occured from which these trees often later died. Trees not repositioned but instead retrained to vertical by pruning lived longer. Ambrosia beetles also attacked wind-stressed trees and caused a long-term decline. Slow moving hurricanes significantly damaged peach trees by waterlogging the soil, which killed roots and helped primary pathogens such as Phytophthora sp. to attack the tree crown. This was followed by secondary pathogens like Oxyporous sp., which attacked the internal woody cylinder. Initial trunk damage appeared localized; however, trees continued to die over a number of years. Experience showed that whole orchard removal on severe waterlogged sites was the best economical response.
672 The Impact of East Coast Hurricanes on Apples
Authors: Marini Richard P. , Barden John , Schupp James
Published: February 2019

Hurricanes or strong winds occasionally damage apple trees in the northeastern and mid-Atlantic regions of the U.S. Following the wind event, trees may be leaning or may be lying flat on the ground with extension root damage. Commercial growers generally pull trees upright while the ground is still moist and support the tree or just the trunk with various types of posts providing support to a height of about 60 to 200 cm above ground. In some cases the trees are pulled partially upright and propped up with boards or sand bags may be placed on the upwind side of the tree. Research data are not available for comparing various methods of treating the trees following wind damage, but field observations indicate that trees perform well if trees are pulled upright within 2 or 3 weeks after the wind event. Data from rootstock research plantings from several states indicate that tree anchorage is influenced by the combination of scion cultivar and root-stock. In Virginia in 1989, Hurricane Hugo brought wind gusts of about 95 km·h–1 when the ground was completely saturated by heavy rains. Trees in several plantings designed to evaluate rootstocks or cultivars were evaluated for the extent of leaning following the storm. The percentage of leaning trees on M.26 EMLA was <10% for `McIntosh' and `Golden Delicious' and 40% for `Delicious'. Susceptibility of trees on M.7A was also influenced by scion cultivar, with 0% for `Golden Delicious' and `Empire', 2% for `Redchief Delicious', and 88% for `TripleRed Delicious'.
675 Program Evaluation Resources and Reporting Methods
Authors: Meyer Mary Hockenberry
Published: February 2019

Several traditional print extension resources have been published on program evaluation, including Evaluating Impact of Extension Programs, by R. Rennekamp, P. Warner, and R. Maurer, 1996, Univ. of Kentucky; and Evaluation for Accountability, by B. Sawer, 1992, Oregon State Univ. Additional resources from other agencies, such as the Minnesota Department of Human Services' publication Measuring the Difference Volunteers Make can aid in the evaluation of extension programs. New reporting methods are now being used to present information and program evaluation such as Minnesota Impacts http://www3.extension.umn.edu/mnimpacts/index.asp, and Oregon Invests. This workshop session will define terms important in evaluation reporting, suggest resources to use, and propose a method of reporting evaluation information of similar projects in environmental horticulture programs throughout the United States.
Differential Response to Floral Infection by Botrytis cinerea within the Genus Pelargonium
Authors: Uchneat Michael S. , Spicer Kathryn , Craig Richard
Published: February 2019

The objective of this study was to identify geranium cultivars that exhibit differential reactions to floral inoculation with Botrytis cinerea Per. ex. Fr. Sixty-two genotypes, including both cultivars and breeding lines, were evaluated from several Pelargonium species. Resistant genotypes included the diploid Pelargonium peltatum (L.) L'Herit. cultivar King of Balcon and the diploid Pelargonium ×hortorum L.H. Bail. cultivar Ben Franklin, as well as the diploid Pelargonium peltatum accession 93-1-33 developed from an accession obtained from South Africa. Susceptible genotypes included the putative tetraploid Pelargonium peltatum cultivar Simone. Floral resistance was not correlated with foliar resistance. Diploid genotypes appeared to have greater resistance than tetraploid genotypes, and P. peltatum cultivars more resistance than P. ×hortorum cultivars. In addition, the association of petal number and resistance was investigated.
Distribution of Urea-derived Nitrogen Supplied to Apple Leaves
Authors: Khemira Habib , Righetti Timothy L. , Azarenko Anita N.
Published: February 2019

Fruit tree responses to foliar urea sprays are variable. We hypothesized that such variability is a function of leaf age-related changes in urea-N mobility after urea is absorbed. Two experiments were conducted to study the distribution of urea-derived N in shoots and branches of apple (Malus ×domestica Borkh.) trees. Urea labeled with 15N was applied to young expanding leaves in spring and to senescing spur leaves in fall. At the low concentrations used [0.5%, 1%, and 2% (w/v)], very little spring-applied 15N was found in tissues other than the treated leaf. Fall-applied urea-15N, however, was detected in high concentrations in dormant buds and bark of the spurs to which the treated leaves were attached. Almost no N was exported to neighboring tissues. The following spring, there was some redistribution of labeled N to adjacent buds. Foliar urea sprays applied immediately after harvest contributed most to bud N; less urea-N was exported to the buds following later fall applications.
Heat-retentive Films for Increasing Soil Temperatures during Solarization in a Humid, Cloudy Environment
Authors: Chase Carlene A. , Sinclair Thomas R. , Chellemi Daniel O. , Olson Stephen M. , Gilreath James P. , Locascio Salvadore J.
Published: February 2019

Although summer soil solarization is a viable technique for the control of soilborne pests, periods of cloudy skies and high rainfall typical of the southeastern United States limit the heating of soils. This study was devised to evaluate whether polyethylene films designed for improved heat conservation could increase soil solarization temperatures under humid environmental conditions. Soil solarization was conducted in Summer 1996 at Quincy, Gainesville, and Bradenton: located in north, north central, and west central Florida, respectively. Temperatures at soil depths of 5, 10, and 25 cm were higher under clear solarization films than under black polyethylene. A clear, thermal-infrared absorbing film (TIR) was consistently more effective in increasing soil temperature than was a double-layered, clear bubble film or a 30 μm clear, low-density polyethylene film. Soil temperatures under all film types were reduced by rainfall, but remained highest under TIR film. On cloudy days with light rainfall, temperatures under TIR film exceeded 45 °C at 5 cm depth. Soil temperatures rose rapidly when rainy weather was followed by a clear day. Cumulative exposure to temperatures ≥45 and 50 °C was greater with the TIR film than with the other films, indicating that it has the greatest potential for soil solarization in humid climates.
Rapid Sex-typing of Asparagus for Male Hybrid Seed Production using n-Propyl N-(3,4-dichlorophenyl)carbamate (NPC)
Authors: Aneja M. , Gianfagna T.J. , Garrison S.A. , Durner E.F.
Published: February 2019

Precocious flowering can be induced in asparagus (Asparagus officinalis L.) seedlings with N-phenylcarbamate herbicides, such as n-propyl N-(3,4-dichlorophenyl) carbamate (NPC); however, only ≈50% of the treated seeds produce flowering plants because these compounds inhibit germination and seedling emergence. We have improved the treatment method by determining the environmental conditions, timing, dose, and duration needed to maximize the percentage of germination, emergence, and flowering. Imbibing seeds in water for 5 days, and then treating germinated seeds with 0.4 mm NPC for 5 days after radicle emergence, with seedling aeration in the light, resulted in the production of flowering seedlings from >90% of the treated seeds. For freshly harvested seeds, in which germination rates are more variable than aged seeds, individual seedlings must be transferred to NPC within 1 day after radicle emergence to produce a high percentage of flowering plants. For seven male asparagus cultivars, chemical induction of flowering in seedlings with NPC produced a sex ratio similar to that of field-grown plants, demonstrating that NPC induces flowering without altering floral differentiation or sex expression. This method can be used for rapidly and accurately identifying the percentage of females in “male” cultivars.
Differences in Grape Phylloxera-related Grapevine Root Damage in Organically and Conventionally Managed Vineyards in California
Authors: Lotter D.W. , Granett J. , Omer A.D.
Published: February 2019

Secondary infection of roots by fungal pathogens is a primary cause of vine damage in phylloxera-infested grapevines (Vitis vinifera L.). In summer and fall surveys in 1997 and 1998, grapevine root samples were taken from organically (OMVs) and conventionally managed vineyards (CMVs), all of which were phylloxera-infested. In both years, root samples from OMVs showed significantly less root necrosis caused by fungal pathogens than did samples from CMVs, averaging 9% in OMVs vs. 31% in CMVs. Phylloxera populations per 100 g of root did not differ significantly between OMVs and CMVs, although there was a trend toward higher populations in OMVs. Soil parameters, percent organic matter, total nitrogen, nitrate, and percent sand/silt/clay also did not differ significantly between the two regimes. Cultures of necrotic root tissue showed significantly higher levels of the beneficial fungus Trichoderma in OMVs in 1997 but not in 1998, and there were significantly higher levels of the pathogens Fusarium oxysporum and Cylindrocarpon sp. in CMVs in 1998 but not in 1997. Implications for further research and for viticulture are discussed.
Suboptimal Winter Chilling Impedes Development of Acrotony in Apple Shoots
Authors: Cook Nigel C. , Jacobs Gerard
Published: February 2019

In 1997, 1-year-old, unbranched, ≈1-m-long shoots of the apple (Malus ×domestica Borkh.) rootstock `Merton-Immune 793' (MI.793) were selected at random from two commercial stoolbeds in the Western Cape, South Africa, during the dormant period. One site has mild winters [307 Utah Chill Units (CU) in 1997, 34°S, 300 m] while the other is moderately cold (1497 CU in 1997, 33°S, 950 m). In 1998, `Granny Smith' shoots were collected from a mature orchard in another warm area (574 CU in 1998, 34°S, 116 m). Shoots were prepared and forced at 25 °C with continuous illumination. During dormancy the developmental rate was determined of the terminal bud, and of both distally and proximally situated lateral buds, with or without the inhibitory influence of a distal disbudded shoot piece (10 cm long). In the moderately cold area, the growth rate of the terminal bud increased shortly before spring budburst such that a weak acrotonic tendency was established. The shorter dormant period, as experienced with the mild winters common to the apple-growing regions of the Western Cape, impeded the full development of acrotony and subsequent apical control. With less chilling (mild areas) a basitonic tendency remained. Budburst was slower and more erratic, and inhibition by the distal shoot parts was accentuated. Delayed foliation may be due more to correlative inhibition than to endodormancy. When lateral buds are released from paradormancy they exhibit a growth potential similar to, or, with less chilling, even greater than, that of the terminal bud. This permits a greater expression of autonomy between shoots.