bluuebunny/crossref_metadata_2025 huggingface dataset:
MANAGEMENT OF DOWNY AND POWDERY MILDEW FOR WINTER SQUASH
Authors: Beany A.H. , Pernezny K. , Stoffella P. J. , Havranek N. , Sanchez J.
Published: February 2019

Control of downy (Pseudoperonospora cubensis) and powdery [(Podosphoera xanthii (Sphaerotheca fuliginea)] mildew on `Sweet Dumpling' winter squash (Cucurbita maxima) was evaluated at the University of Florida, IFAS, Indian River Research and Education Center (IRREC), in Fort Pierce, Florida during the Spring of 2005. Three foliar spray fungicide treatments were evaluated against an untreated control. Powdery and downy mildew ratings (estimated percentage of foliage damage) and marketable yields (mt/ha) were measured. Plants in the untreated plots had significantly higher powdery and downy mildew ratings. All fungicide treatments significantly reduced both mildews. There were no significant differences among treatments for marketable yield. Although the level of disease occurrence was not sufficient to reduce yields, Gavel alternated with Nova, Bravo Ultrex weekly, and Cabrio + Forum alternated with Bravo Ultrex + Manzate 75WG reduced downy mildew by ≥50%.
GROWING OLIVES IN TEXAS; REGULATION OF FLOWERING IN `ARBEQUINA'
Authors: Nasir S. , Malik A. , Bradford Joe M. , Brockington Jim
Published: February 2019

Olives have not been commercially grown in Texas because earlier investigators considered Texas climate inappropriate for olive cultivation. No experimental investigations were conducted in Texas. Olives, however, grow in very diverse climatic conditions throughout the world, and >2000 cultivars of olives have been reported worldwide. To study temperature regulation of flowering in olives, relatively inexpensive growth chambers were developed. These walk-in type growth chambers can be made with about $7K where as costs of similar size commercial chambers could reach to $100K. Using these chambers we have discovered that flowering and fruiting in `Arbequina' cultivar of olives could be achieved under mild conditions with almost no typical chilling (<7 °C) hours. We postulated that it is the high daytime temperature that prevent flowering in olives in southern Texas rather than lack of chilling hours. Further experiments demonstrated that subjecting trees to 24 °C for 4 hours everyday during winter could significantly reduce flowering in Arbequina. It appeared that several sites near coastal Texas, particularly Galveston, may not experience high daytime temperatures and hence could be suitable for olive cultivation. Trees have now been planted in these sites, but serendipitously several olive trees, >25 years old, were found in Galveston that had been flowering and fruiting for years. Olive accessions have also shown adaptability to local climates at various other sites in Southern Texas. Our initial surveys of olives groves established during the last 4–6 years have revealed the existence of at least two trees with remarkable adaptability to Texas conditions. One of these trees had flowered and fruited in the Rio Grand Valley where earlier workers had predicted that flowering in olives will not occur. Thus, there appears some genetic diversity and clonal variations among limited number of existing olive trees in Texas that there is a hope for viable cultivations of olives in Texas. Clones from these trees have now been produced which will be planted at various locations within the Texas Valley to evaluate their performance in the next few years.
LABORATORY METHOD TO ESTIMATE INCIDENCE OF FRUIT SPLITTING IN CULTIVATED BLUEBERRY
Authors: Marshall Donna A. , Spiers J.M. , Curry K.J. , Stringer S.J.
Published: February 2019

Fruit splitting takes place in rabbiteye and southern highbush blueberries when a preharvest rainfall occurs and when fruit are fully ripe or approaching full ripeness. This study was initiated to develop a laboratory method to identify the rain-related incidence of splitting in cultivated blueberries. Multi-year field surveys of select rabbiteye and southern highbush cultivars show that the incidence of rain-related splitting is strongly cultivar dependent. Year to year variations within cultivars reflected yearly differences in ripening times and amounts and timing of rainfall. Laboratory values of forced splitting and field splitting data of three years show a strong correlation indicating that the incidence of fruit splitting can be accurately estimated by laboratory methods. Soaking the berries in distilled water 14 hours at room temperature gives a confident determination of splitting tendencies. Blueberry breeders can use this method to evaluate new potential blueberry cultivars for splitting tendencies. This laboratory method could also be used by geneticists to test selections accurately for splitting tendencies as part of routine screening. This can lead to a long-term goal of reducing splitting susceptible blueberries in commercial plantings.
NUTRIENT DEFICIENCIES OF PENTAS LANCEOLATA `BUTTERFLY RED'
Authors: Gibson James L. , Groninger Jude , Wombles Sharon , Campbell Kathryn
Published: February 2019

Elemental deficiencies of N, P, K, Ca, Mg, S, Fe, Mn, Cu, Zn, or B were induced in plants of Pentas lanceolata `Butterfly Red'. Rooted stem cuttings were planted in 4.87-L plastic containers and fertilized with a complete modified Hoagland's solution or this solution minus the element that was to be investigated. Plants were harvested to measure dry weights when initial foliar symptoms were expressed and later under advanced deficiency symptoms. Deficiency symptoms for all treatments were observed within 7 weeks. The most dramatic expression of foliar symptoms occurred with N (medium green young leaves with interveinal chlorosis on base and tip), S (spindle-like young and recently mature leaves), Cu (purple-brown roots and young leaves with downward pointed leaf tips), and B (multiple youngest leaves arising from shoot tip). At the initial stage, all nutrient-deficient plants had similar dry weights, when compared to the control. Dry weights of plants treated with solutions not containing P were significantly lower when compared to the control under an advanced deficiency. In order to help prevent the development of deficiencies, minimal critical tissue levels have to be determined for adaptation by the greenhouse industry for nutritional monitoring.
CRAPE MYRTLE EVALUATIONS IN SOUTH MISSISSIPPI
Authors: Knight Patricia R. , Anderson John M. , McLaurin Wayne , Coker Christine
Published: February 2019

Lagerstroemia indica x fauriei `Tonto' and `Sioux' were planted in March, 1995. All other cultivars were planted in October, 1985. Plants were planted into a Ruston sandy loam on a 12 × 12 ft (3.7 × 3.7 m) spacing. Trees were pruned to develop multiple trunks. Trees are pruned annually in winter to remove any limbs smaller than ¼ in (0.6 cm) in diameter. Pruning cuts are made 6–8 in (15.2–20.3 cm) above prior cuts. Severe pruning is performed every five years. Trees were evaluated at 2-week intervals during the flowering season to determine total length of flowering and duration of good to superior flowering. Growth indices (height + width + perpendicular width)/3 were recorded after plants were dormant. Total days of flowering and floral display (0–5 with 0 representing no flowers and 5 representing superior flowering) were rated. `Muskogee' had the greatest growth index after the 2004 growing season. `Seminole' had the least. However, `Seminole' did have the greatest number of flowering days. `Biloxi' had the fewest flowering days. `Tonto' had the most good to superior flowering days while `Tuskegee' and `Muskogee' had the fewest.
PERFORMANCE OF HEIRLOOM AND LATE BLIGHT RESISTANT HEIRLOOM-TYPE TOMATO HYBRIDS IN ORGANIC AND CONVENTIONAL FIELD TRIALS
Authors: Davis Jeanine M. , Gardner Randolph G.
Published: February 2019

There is a good market for heirloom tomatoes that, according to many consumers, taste better than regular tomatoes. Unfortunately, most heirloom tomatoes have little disease resistance, tend to crack, are rough in appearance, and are not uniform in size. Randy Gardner recently developed several new indeterminate hybrid tomatoes with the goal of combining the flavor of heirloom tomatoes with the disease resistance, uniform size, and good shipping characteristics of more modern varieties. Two tests, using organic and conventional practices, were conducted in Waynesville, N.C., in which three popular heirloom varieties (German Johnson, Mr. Stripey, and Cherokee Purple) and four late blight resistant hybrids (NC 0455, NC 0571, NC 0576, and NC 05114), replicated four times, were grown using a high trellis system. The highest yields were obtained with German Johnson NC 0455, and NC 0576 in the conventional trial and German Johnson NC 0455, and NC 0571 in the organic trial. Public taste test results revealed that the experimental hybrid cluster type, NC 05114, was ranked by over 82% of the participants as good or excellent. NC 0455 was rated as good or excellent by >83% of the participants, which was better than the popular heirlooms Cherokee Purple and Mr. Stripey. This study demonstrated that the heirloom-type hybrid tomatoes could be successfully grown in organic and conventional systems in Western North Carolina and that two out of the four tested had flavor ratings similar to, or better than, the three heirloom varieties tested.
GRAFTING OF TRIPLOID WATERMELON ON SQUASH AND GOURD ROOTSTOCKS
Authors: Cushman Kent , Huan Jin , Cushman Lisa
Published: February 2019

Grafting of watermelon scions onto squash or pumpkin (Cucurbita), bottle gourd (Lagenaria), wax gourd (Benincasa), or watermelon (Citrullus) rootstocks is practiced in most of the major watermelon production regions of the world. Advantages of grafting are protection against soilborne diseases, resistance to nematodes, and overall increased vigor of plants resulting in higher yield and better fruit quality. Disadvantages include increased cost of seedling production and the potential of altered horticultural characteristics of cultivars used as scions. With problems associated with watermelon vine decline in recent years in Florida and the increasing cost of soil fumigants, the use of grafted watermelon seedlings should be explored. Four grafting techniques for watermelon are common: splice, side insertion, approach, and hole insertion. The approach graft, though labor intensive, doesn't require exacting control of temperature and humidity after making grafts and may be well suited to south Florida conditions. All other grafts require excellent control of the post-grafting environment and a careful transition from low light and high humidity to high light and low humidity. A preliminary evaluation of grafted and ungrafted plants during Fall 2005 compared `Tri-X 313', `Palomar', `Precious Petite', and `Petite Perfection' on several rootstocks. Most rootstock/scion combinations produced fruit of normal size, appearance (internal and external), and soluble solids content. Some combinations resulted in irregular, pumpkin-shaped fruit and slightly higher incidences of hollowheart.
VALUE-ADDED SWEETPOTATO PRODUCTS
Authors: Duran G.R. , Coggins P.C. , Wilbourn J.A.
Published: February 2019

Nationally, about 97,900 acres of sweetpotatoes (Ipomoea batatas) were planted for 2001 with a yield of 156 cwt. Many of the sweetpotatoes are left in the field as unmarketable culls. A juicing technique used to produce a value-added product from the culls would be valuable to the sweetpotato farmer and the industry as a whole. This process would enable the farmers to turn an unmarketable product into a potentially profitable juice product. The research objective was to determine the usable yields of sweetpotato culls by extracting the juice. This would provide a value-added juice product for sweetpotato farmers. Juice would be easily transported and stored. Sweetpotato culls were collected, washed, and dried. Samples were chopped, weighed and processed with an automatic juice extractor (Juiceman Jr., Mount Prospect, Ill.). The extracted juice and remaining pulp were removed and weighed. Percent juice, pulp, and loss were calculated on a weight basis. Results showed that when processed with a grinding/centrifugal type juice extractor, an average of 53.6% of the initial weight from sweetpotato culls can be extracted as juice. Also, as the initial weight of the culls increased, the percent juice extracted increased. The combined solids collected from the extracted pulp and the pulp remaining after equipment disassembly was on average 42.66% of the initial weight. The unsalvageable percent of juice and pulp was on average 3.93%. These results suggest that sweetpotato culls yield about half of their original weight as juice. Juice extraction may be a viable option for processing non-market grade sweetpotato culls. Sweetpotato juice may be consumed as a beverage or combined with other juices to form a variety of juice blends.
MICROSATELLITE MARKERS FOR VERIFYING PARENTAGE OF PECANS
Authors: Grauke LJ , Mendoza-Herrera Maria Azucena , Loopstra Carol , Thompson Tommy E.
Published: February 2019

Microsatellite or Simple Sequence Repeat (SSR) markers are being developed in ongoing research in the USDA ARS Pecan Breeding Program. These co-dominant markers provide a powerful tool for the verification of parentage. To confirm their utility, SSR profiles were used to confirm the parentage of 19 of the 25 controlled crosses released by the breeding program. Questions were raised concerning the parentage of some crosses thought to be known. When the genotype of the maternal parent is known, the paternal genotype necessary to have produced the progeny can be determined. A SAS program was written to query a database that includes 288 pecan accessions to find appropriate paternal genotypes given a maternal pattern. If neither parent is known, all possible parental combinations can be derived based on the progeny. Putative parents can be qualified on the basis of genotype as well as other evidence, such as nut morphology, dates of origin, locations of origin, and dichogamy. Using these techniques, putative parents are suggested for the historic cultivars `Riverside' and `Western'. Although the probabilities for a particular genotypic pattern can be determined based on allele frequencies within the population, assigning numeric probabilities to other evidence is more challenging. Meticulous records are necessary to establish the linkage between an inventory of an accession and its historic origin, thereby placing putative parents in combination at the proper place and appropriate time. Records of USDA–ARS National Plant Germplasm System, as exemplified by logbooks and vouchers of the McKay Collection of the National Arboretum, provide evidence for confident molecular genetic verification of cultivar identity and parentage, increasing the value of the living accessions in the NPGS.
VIRUS DISTRIBUTION IN FIELD GROWN SWEETPOTATO VINES IN AFRICA
Authors: Miano D.W. , LaBonte D. R. , Clark C. A.
Published: February 2019

Sweet potato virus disease (SPVD) is a major constraint to sweetpotato production in East Africa. The disease is a result of co-infection with sweet potato feathery mottle virus (SPFMV) and sweet potato chlorotic stunt virus (SPCSV). Some local sweetpotato genotypes have been reported to recover from, or have localized distribution of SPVD, suggesting that the disease is not fully systemic. This has led to the suggestion that uninfected cuttings may be obtained from previously infected plants. Experiments were set to determine the possibility of obtaining cuttings long enough for propagation that are free from virus infection. This would form a basis for recommending to the local small-holder farmers of a way to reduce losses due to the disease. Field grown sweetpotato vines were cut into three pieces (15, 15 to 30, and >30 cm from the apex) and tested for SPCSV and SPFMV. Nine genotypes were selected from a group of 21 local clones and used for this study. The two viruses were equally present in all the three sections of infected vines, indicating that it is not easy to obtain a virus free cutting for field propagation from an infected vine.
AN UPDATE ON EVALUATION OF VIRUS STATUS IN THE HEIRLOOM SWEETPOTATO GERMPLASM MATERIALS WITH REAL-TIME PCR TECHNOLOGY
Authors: Ling K.S. , Clark C.A. , Kokkinos C. , Bohac J. R. , Hurtt S.S. , Jarret R. L. , Gillaspie A. G.
Published: February 2019

Sweet potato virus disease (SPVD) is the most devastating virus disease on sweetpotato [Ipomoea batatas (L.) Lam] world wide, especially in East Africa. However, weather it is present in the U.S. is unknown. SPVD is caused by co-infection of sweetpotato feathery mottle virus (SPFMV) and sweetpotato chlorotic stunt virus (SPCSV). Presence of two other potyviruses, sweetpotato virus G (SPVG) and Ipomoea vein mosaic virus (IVMV) has also been confirmed in the U.S. Sweet potato leaf curl virus (SPLCV), a whitefly (Bemisia tabaci) transmitted Begomovirus, also has the potential to spread to commercial sweetpotato fields and poses a great threat to the sweetpotato industry. The U.S. collection of sweetpotato germplasm contains about 700 genotypes or breeding lines introduced from over 20 different countries. Newly introduced sweetpotato germplasm from foreign sources are routinely screened for major viruses with serology and graft-transmission onto indicator plants (Ipomoea setosa). However, a large portion of this collection including heirloom cultivars or old breeding materials has not been systemically screened for these major sweetpotato viruses. In this study, a total of 69 so-called heirloom sweetpotato PI accessions were evaluated for their virus status. We used Real-time PCR to detect five sweetpotato viruses, including four RNA viruses (SPCSV, SPFMV, SPVG, and IVMV) and one DNA virus (SPLCV). A multiplex Real-time RT-PCR system was developed to detect three RNA viruses (SPFMV, SPVG, and IVMV). Preliminary data indicated that about 15% of these heirloom sweetpotato germplasm carried at least one of these viruses tested. Details on virus infection status will be presented.
INDIVIDUAL SHRINK WRAPPING OF SWEETPOTATOES: A VALUE-ADDED MARKETING TREND
Authors: Picha D.H.
Published: February 2019

The use of heat shrinkable plastic film for wrapping individual sweetpotato roots was evaluated as a form of value-added packaging. Individual shrink wrapping of sweetpotatoes is a recently adopted but increasingly used retail marketing technique. The shrink wrapping process involves enclosing individual roots in shrink film which is cut and heat sealed followed by transfer through a heat tunnel to create a tightly sealed package. Film thickness ranges from 40 to 100 microns (gauge). Manual, semi-automatic, and automatic application methods are available. Fully automated commercial methods approach a speed of 1 wrapped root per second. Shrink wrapping adds value to fresh market sweetpotatoes by enhancing appearance, reducing weight loss, and allowing for individual root labeling. Various film types and thicknesses were tested under simulated retail conditions. Root weight loss from shrink wrapped roots was significantlyreduced during storage, ranging from a total of 0.5% in wrapped roots to 2.5% in unwrapped roots after 3 weeks of ambient storage. There was an inverse relationship between film thickness and root weight loss, with the thicker gauge films showing the least amount of weight loss. Film type and thickness did not influence overall root flavor and sweetness perception. In order to reduce the incidence of surface mold, the root must be completely dry before wrapping. This form of packaging offers significant potential for enhancing retail consumer demand.
INTERIM RESULTS FROM THE SWEET POTATO RAMP GRANT IN MISSISSIPPI.
Authors: Reed J.T. , Williams M.R. , Fleming D.
Published: February 2019

Results from research funded by RAMP (Risk Assessment and Mitigation Program) funds conducted with sweetpotato growers in Mississippi during 2004 and 2005 are discussed. Insects were sampled on a weekly (2004) or biweekly (2005) schedule on land planted to potatoes with and without insecticidal input. Potatoes were harvested from each cooperator's field and evaluated for insect damage one or more times at the end of the season. Insect pest populations in Mississippi sweetpotatoes were relatively low during 2004 and 2005. Under these conditions, the percentage of sweetpotatoes damaged by insects was only slightly reduced by insecticides. Chrysomelid leaf beetles including flea beetles, cucumber beetles and tortoise beetles were the most obvious group of pest insects. The most prominent insect species in sweep net samples during the season was the sweetpotato flea beetle, however damage by this pest was negligible. The most damaging insect based on our evaluation of root damage was the twelve-spotted cucumber beetle. Root feeding by whitefringed beetles, white grubs, and sugarcane beetles was sporadic within the fields in the study, and damage by these insects was generally minimal in 2004 and 2005. Preliminary assessments of the effect of crops planted the year previous to the planting of sweetpotatoes indicate the following order of greater to lesser insect damage: pasture, soybeans, corn, sweetpotato, and cotton. Delay of harvest beyond the optimum harvest date tended to increase insect damage in marketable roots. Pesticide evaluations associated with the study indicate that some reduction in damaged roots may be derived from application of a soil-incorporated insecticide at lay by.
RESISTANCE OF WATERMELON (CITRULLUS LANATUS VAR. CITROIDES) GERMPLASM FOR RESISTANCE TO ROOT-KNOT NEMATODES
Authors: Thies J. A. , Levi A.
Published: February 2019

Root-knot nematodes (Meloidogyne incognita, M. arenaria, and M. javanica) cause severe damage to watermelon and resistance has not been identified in any watermelon cultivar. In greenhouse tests, we evaluated 265 U.S. plant introductions (PIs) for nematode resistance (based on root galling and nematode reproduction), and identified 22 PIs of Citrullus lanatus var. citroides as moderately resistant to M. arenaria race 1. In subsequent tests, these 22 PIs exhibited low to moderate resistance to M. incognita race 3 and M. arenaria race 2. Three watermelon (C. lanatus var. lanatus) cultivars (Charleston Gray, Crimson Sweet, and Dixie Lee), three C. colocynthis PIs, and four C. lanatus var. citroides PIs, all previously shown to be susceptible to M. arenaria race 1, were susceptible to M. incognita race 3 and M. arenaria race 2. The C. lanatus var. citroides PIs that are most resistant to both M. incognita and M. arenaria should be useful sources of resistance for developing root-knot nematode resistant watermelon cultivars.
Potential Implications of Medicinal Plant Production in Controlled Environments: The case of Feverfew (Tanacetum parthenium)
Authors: Fonseca Jorge M. , Rushing James W. , Rajapakse Nihal C. , Thomas Ronald L. , Riley Melissa B.
Published: February 2019

The purpose of this review is to promote a discussion about the potential implications of herb production in controlled environments, focusing on our recent works conducted with feverfew. Research suggests that the content of secondary metabolites in medicinal plants fluctuates with changing environmental conditions. Our studies with feverfew (Tanacetum parthenium [L.] Schultz-Bip., Asteraceae) lend support to this hypothesis. Feverfew plants exposed to different water and light conditions immediately before harvest exhibited changes in content of some secondary metabolites. The highest yield of parthenolide (PRT) was in plants that received reduced-water regimes. Phenolics concentration however, was higher in plants receiving daily watering. Light immediately before harvest enhanced accumulation of PRT, but reduced the phenolic content. Notably, PRT decreased at night whereas total phenolics decreased during the photoperiod and increased at night. PRT also increased with increased plant spacing. UV light supplementation increased PRT only in plants that had undergone water stress, whereas phenolics increased when UV was applied to continuosly watered plants. Clearly, production of medicinal plants under greenhouse conditions is a promising method for controlling levels of phytochemicals through manipulation of light and water as discussed here, and possibly other environmental factors such as temperature and daylength. However, better understanding of how the environment alter secondary metabolite levels is needed as it was revealed that manipulating the environment to favor increased accumulation of one group of phytochemicals could result in a decline of other key metabolites.
Aeroponic and Hydroponic Systems for Medicinal Herb, Rhizome, and Root Crops
Authors: Hayden Anita L.
Published: February 2019

Hydroponic and aeroponic production of medicinal crops in controlled environments provides opportunities for improving quality, purity, consistency, bioactivity, and biomass production on a commercial scale. Ideally, the goal is to optimize the environment and systems to maximize all five characteristics. Examples of crop production systems using perlite hydroponics, nutrient film technique (NFT), ebb and flow, and aeroponics were studied for various root, rhizome, and herb leaf crops. Biomass data comparing aeroponic vs. soilless culture or field grown production of burdock root (Arctium lappa), stinging nettles herb and rhizome (Urtica dioica), and yerba mansa root and rhizome (Anemopsis californica) are presented, as well as smaller scale projects observing ginger rhizome (Zingiber officinale) and skullcap herb (Scutellaria lateriflora). Phytochemical concentration of marker compounds for burdock and yerba mansa in different growing systems are presented.
Pruning Strategies to Maximize Tropical Mango Production From the Time of Planting to Restoration of Old Orchards
Authors: Davenport Thomas L.
Published: February 2019

Pruning is an unavoidable necessity of virtually all arboreal fruit crops. In the tropics and subtropics, pruning of mango (Mangifera indica L.) is particularly important due to its tendency for frequent flushes, especially in humid tropics. Commercial orchards must maintain control of both tree size and orchard productivity in order to remain productive. Tip, formation, and severe pruning can be used in a variety of circumstances to produce predictable and useful results for a variety of purposes. For example, tip pruning can be used to encourage frequent flushing and branching of young trees to bring them into commercial production years earlier than if left alone. It can also stimulate timely flushes of lateral stems in an annual program to maintain tree size and prepare trees for synchronous flowering. Formation pruning shapes trees in an overgrown orchard to receive the maximum amount of light for high productivity and sets them up for annual pruning in a flowering management program. Severe pruning coupled with subsequent tip pruning of huge, nonproductive trees facilitates rapid restoration of orchard production. Each of these types of pruning can be used to get mango trees into production quickly and thereafter maintain maximum annual production while maintaining their desired size.
The Role of AVRDC–The World Vegetable Center in Enhancing and Promoting Vegetable Production in the Tropics
Authors: Palada Manuel C. , Kalb Thomas J. , Lumpkin Thomas A.
Published: February 2019

AVRDC–The World Vegetable Center was established in 1971 as a not-for-profit international agricultural research institute whose mission is to reduce malnutrition and poverty among the poor through vegetable research and development. Over the past 30 years, AVRDC has developed a vast array of international public goods. The Center plays an essential role in bringing international and interdisciplinary teams together to develop technologies, empower farmers, and address major vegetable-related issues in the developing world. In its unique role, AVRDC functions as a catalyst to 1) build international and interdisciplinary coalitions that engage in vegetable and nutrition issues; 2) generate and disseminate improved germplasm and technologies that address economic and nutritional needs of the poor; 3) collect, characterize, and conserve vegetable germplasm resources for worldwide use; and 4) provide globally accessible, user-friendly, science-based, appropriate technology. In enhancing and promoting vegetable production and consumption in developing world, AVRDC's research programs contribute to increased productivity of the vegetable sector, equity in economic development in favor of rural and urban poor, healthy and more diversified diets for low-income families, environmentally friendly and safe production of vegetables, and improved sustainability of cropping systems. Recent achievements at AVRDC that greatly impact tropical horticulture in the developing world include virus-resistant tomatoes raising farmers income, hybrid sweet pepper breaking the yield barrier in the tropics, flood-resistant chili peppers opening new market opportunities, broccoli varieties for monsoon season, pesticide-free eggplant and leafy vegetable production systems and fertilizer systems that protect the environment. Beyond vegetable crops, AVRDC is playing an important role in expanding and promoting research and development efforts for high value horticultural crops, including fruit, ornamentals, and medicinal plants through its new Global Horticulture Initiative. AVRDC believes that horticulture crop production provides jobs and is an engine for economic growth. The important role AVRDC–The World Vegetable Center plays in developing and promoting tropical horticultural crops is discussed in this paper.
Reproductive Biology of Clethra alnifolia
Authors: Reed Sandra M.
Published: February 2019

Breeding efforts in Clethra alnifolia L., an ornamental shrub native to the Eastern U.S., are hindered by a lack of information on the reproductive behavior of this species. The objective of this study was to evaluate self-compatibility, time of stigma receptivity, and the relationship between time of pollen shed and stigma receptivity in C. alnifolia. Stigma receptivity and changes in floral morphology were monitored over a 7-day period beginning at flower opening. Pollen germination and pollen tube growth in styles were examined following self- and cross-pollinations using fluorescence microscopy. Seed set and germination were compared following self- and cross-pollinations. Anthers began to dehisce in `Hummingbird' and `Ruby Spice' the day after flowers opened, but stigmas did not become fully receptive to pollen until 2 days later. An increase in the length of pistils was observed following flower opening. Maximum elongation of pistils occurred at approximately the same time stigmas became receptive and could be utilized as an indicator of receptivity. While self-pollen tubes appeared to grow slightly slower than cross-pollen tubes, there was no indication of a self-incompatibility system acting at the stigmatic or stylar level in C. alnifolia. Self-pollinations of `Hummingbird' and `Ruby Spice' produced fewer seeds than did cross-pollinations of these cultivars. Germination of all seed obtained from this study was too poor to allow a comparison of germination rates of the self- and cross-pollinated seed. However, because a few self-progeny were obtained, emasculation is recommended when making controlled pollinations. The presence of a late acting self-incompatibility system or early-acting inbreeding depression was proposed as being responsible for the lower seed set following self-pollination.
Evaluation of Midwinter Cold Hardiness among 25 Rabbiteye Blueberry Cultivars
Authors: Ehlenfeldt Mark K. , Ogden Elizabeth L. , Rowland Lisa J. , Vinyard Bryan
Published: February 2019

The midwinter cold hardiness of 25 rabbiteye (V. ashei) blueberry cultivars was assayed across 2 years using a shoot freezing assay. LT50values (i.e. temperature at which 50% of buds are damaged) for the cultivars ranged from –24.9 °C for `Pearl River' (a 50% V. ashei derivative) to –13.7 °C for `Chaucer'. Under New Jersey conditions, numerous cultivars were observed to exhibit dimorphism for dormant floral bud size. Comparisons of bud dimorphism with LT50 values, found dimorphism more common in cultivars with lower floral bud hardiness. LT50 values generally supported empirical observations of winter hardiness, but exceptions suggest that additional factors contribute to observed winter hardiness under field conditions.
Biomass Production and Pigment Accumulation in Kale Grown Under Increasing Photoperiods
Authors: Lefsrud Mark G. , Kopsell Dean A. , Augé Robert M. , Both A.J.
Published: February 2019

Consumption of fruit and vegetable crops rich in lutein and β-carotene carotenoids is associated with reduced risk of cancers and aging eye diseases. Kale (Brassica oleracea L. var. acephala D.C.) ranks highest for lutein concentrations and is an excellent source of dietary carotenoids. Kale plants were grown under varied photoperiods to determine changes in the accumulation of fresh and dry biomass, chlorophyll a and b, and lutein and β-carotene carotenoids. The plants were cultured in a controlled environment using nutrient solutions under photoperiod treatments of 6, 12, 16, or 24 hours (continuous). Fresh and dry mass production increased linearly as photoperiod increased, reaching a maximum under the 24-hour photoperiod. Maximum accumulation of lutein, β-carotene, and chlorophyll b occurred under the 24-h photoperiod at 13.5, 10.4, and 58.6 mg/100 g fresh mass, respectively. However, maximum chlorophyll a (235.1 mg/100 g fresh mass) occurred under the 12-hour photoperiod. When β-carotene and lutein were measured on a dry mass basis, the maximum accumulation was shifted to the 16-hour photoperiod. An increase in photoperiod resulted in increased pigment accumulation, but maximum concentrations of pigments were not correlated with maximum biomass production.
Effect of Mycorrhizal Inoculation and Compost Supply on Growth and Nutrient Uptake of Young Leek Plants Grown on Peat-based Substrates
Authors: Perner Henrike , Schwarz Dietmar , George Eckhard
Published: February 2019

Organic horticultural production systems often are characterized by the use of beneficial soil microorganisms because the application of soluble inorganic P or N fertilizers is not endorsed. Due to the limited supply of soluble nutrients in organic production systems, nutrient deficiency may limit plant growth and yield. The sole use of peat for pot-based cultures is also discouraged in organic production systems. Therefore, we have studied viable alternatives for highly soluble fertilizers and pure peat substrates using leek [Allium ampeloprasum L. var. Porrum] as a test plant. Plants were grown on peat-based substrates with different rates of compost additions, and with and without inoculation with arbuscular mycorrhizal (AM) fungi. Inoculation with a commercial AM fungus inoculum resulted in colonization rates of up to 70% of total root length, whereas not inoculated plants remained free of root colonization. Mycorrhizal fungus colonization increased shoot Zn and K concentrations, but did not significantly affect shoot dry matter or shoot N and P concentrations. In contrast, compost addition increased plant growth, and also increased P and K concentrations in plants. We conclude that plants with high rates of mycorrhizal colonization can be obtained on peat-based substrates, but that under these conditions plants may not consistently benefit in growth from the mycorrhizal symbiosis. In contrast, additions of compost are a possible means to improve the substrate quality in organic horticultural production.
Pollination and Seed Production in Viola
Authors: Miyajima Daiichiro
Published: February 2019

The seed producing system in viola (Viola ×cornuta) was investigated to improve seed yield and to save labor. In a flower five anthers sequentially dehisced; pollen grains were continuously supplied to the anterior petal, which played a significant role in pollination, throughout the flowering period. Evidence from pollen and ovule number suggests that the species is facultative autogamy. Each flower opened more than 10 days was independent of the success in fertilization and kept seed producing ability during the flower longevity period. Pollen grains also maintained viability during the flower longevity period. Pollinators were indispensable for pollination of viola, but pollination in viola was done by a different mechanism from the typical insect-mediated pollination that sticky pollen grains adhere to the exposed stigmas. Pollen grains, accumulated around the entrance of the stigmatic cavity, entered into the cavity by the movement of pollinators. Although the visitation of pollinators was occasional, solitary bees primarily contributed to the pollination of viola. On the other hand, germination of pollen grains on the stigmatic surface was under 50%. Seed set was much lower than the germination percentage of pollen grains. A viola flower had the ability for additional pollinations and fertilization for some days after the fertilization success in some ovules in the flower. This characteristic suggested that repeated pollination is effective to increase the number of mature seeds in a capsule.
National Produce Market Barrier Penetration: The Georgia Case
Authors: Epperson J.E. , McPherson P.D. , Stegelin F.E.
Published: February 2019

This study examined factors contributing to the development of the produce industry in Georgia and means of overcoming barriers to entry into the national fresh fruit and vegetable market. A survey of produce growers in Georgia was conducted in 2003–04. Information obtained from the respondents included economic and operational characteristics of grower enterprises and more specifically factors limiting production, expected operational changes, and marketing practices. Grower tendencies were ascertained from survey responses with respect to sales using regression analysis. Factors found important in overcoming barriers to national market entry stem from the degree of specialization and sophistication of producers.
Six-year Evaluation of Brown Citrus and Spirea Aphid Populations in a Citrus Grove and the Effects of Insecticides on these Populations
Authors: Powell Charles A. , Burton Michael S. , Pelosi Robert R. , Rundell Phyllis A. , Ritenour Mark A. , Bullock Robert C.
Published: February 2019

The population densities of the brown citrus aphid (BrCA) (Toxoptera citricidus Kirkaldy) and the spirea aphid (SA) Aphis spiraecola Patch were monitored by scouting weekly for 6 years in a replicated citrus plot treated with 7 insect control regimes: Admire (imidacloprid) applied at 12, 6, 3, or 2 month intervals; Temik applied annually; Meta-Systox-R applied annually; or no insect control. The numbers of both aphid species varied greatly from month to month and year to year. The brown citrus aphid was normally only detected in the fall (August through December) with populations peaking in September, October, or December depending on the year. The spirea aphid could be detected throughout the year during years when overall populations were high. Spirea aphid populations often peaked both in the spring and fall. Annual applications of Temik or Metasystox were ineffective in reducing aphid populations. Generally, all four Admire treatment regimes controlled aphids, although at least 2 annual Admire treatments per year were required to control the spirea aphid during some years.
Impact of Ultraviolet-blocking Plastic Films on Insect Vectors of Virus Diseases Infesting Crisp Lettuce
Authors: Díaz Beatriz M. , Biurrún Ricardo , Moreno Aránzazu , Nebreda Miguel , Fereres Alberto
Published: February 2019

Ultraviolet (UV)-absorbing plastic films are being used as a photoselective barrier to control insect vectors and associated virus diseases in different horticultural crops. A 2-year experiment was carried out in northeastern Spain (Navarra) to evaluate the impact of a UV-blocking film (AD-IR AV) on the population density of insect pests and the spread of insect-transmitted virus diseases associated with head lettuce [Lactuca sativa (L.)]. Results showed that the UV-absorbing plastic film did not loose its ability to filter UV radiation after three lettuce crop cycles (14 months). The UV-absorbing plastic film was effective in reducing the abundance and in delaying the colonization of lettuce by aphids [Macrosiphum euphorbiae (Thomas) and Acyrthosiphum lactucae (Passerini)]. A significant increase in the percentage of marketable plants was achieved under UV-absorbing films due to a reduction in the number of plants infested by aphids and by insect-transmitted virus diseases (mainly potyviruses). Also the UV-absorbing plastic films were effective in reducing the population density of Frankliniella occidentalis (Pergande) and the spread of tomato spotted wilt virus (TSWV) as well as the population density of the lepidopteran pest, Autographa gamma (L.), a common pest of lettuce in Spain. However, no effective control of the greenhouse whitefly Trialeurodes vaporariorum (Westwood) was achieved. The results showed that UV-absorbing plastic films are a very promising tool to protect greenhouse lettuce from the main pests and insect-transmitted virus diseases occurring in northeastern Spain.
Supplemental Foliar Potassium Applications with or without a Surfactant can Enhance Netted Muskmelon Quality
Authors: Lester Gene E. , Jifon John L. , Makus D. J.
Published: February 2019

Netted muskmelon [Cucumis melo L. (Reticulatus Group)] fruit quality (ascorbic acid, β-carotene, total free sugars, and soluble solids concentration (SSC)) is directly related to plant potassium (K) concentration during fruit growth and maturation. During reproductive development, soil K fertilization alone is often inadequate due to poor root uptake and competitive uptake inhibition from calcium and magnesium. Foliar applications of glycine-complexed K during muskmelon fruit development has been shown to improve fruit quality, however, the influence of organic-complexed K vs. an inorganic salt form has not been determined. This glasshouse study investigated the effects of two K sources: a glycine-complexed K (potassium metalosate, KM) and potassium chloride (KCl) (both containing 800 mg K/L) with or without a non-ionic surfactant (Silwet L-77) on melon quality. Orange-flesh muskmelon `Cruiser' was grown in a glasshouse and fertilized throughout the study with soil-applied N–P–K fertilizer. Starting at 3 to 5 d after fruit set, and up to 3 to 5 d before fruit maturity at full slip, entire plants were sprayed weekly, including the fruit, with KM or KCl with or without a surfactant. Fruit from plants receiving supplemental foliar K had significantly higher K concentrations in the edible middle mesocarp fruit tissue compared to control untreated fruit. Fruit from treated plants were also firmer, both externally and internally, than those from non-treated control plants. Increased fruit tissue firmness was accompanied by higher tissue pressure potentials of K treated plants vs. control. In general, K treated fruit had significantly higher SSC, total sugars, total ascorbic acid, and β-carotene than control fruit. Fall-grown fruit generally had higher SSC, total sugars, total ascorbic acid and β-carotene concentrations than spring-grown fruit regardless of K treatment. The effects of surfactant were not consistent but in general, addition of a surfactant tended to affect higher SSC and β-carotene concentrations.
Sensory Quality of `Bing' Sweet Cherries Following Preharvest Treatment with Hydrogen Cyanamide, Calcium Ammonium Nitrate, or Gibberellic Acid
Authors: Clayton Murray , Biasi William V. , Agar I. Tayfun , Southwick Stephen M. , Mitcham Elizabeth J.
Published: February 2019

`Bing' sweet cherry (Prunus avium L.) trees were treated with hydrogen cyanamide (CH2N2) or calcium ammonium nitrate (CaNH4NO3) during dormancy, or gibberellic acid (GA3) 26 days before harvest during three consecutive years. Fruit were evaluated at harvest for sensory taste quality using twenty trained panelists sampling for firmness, sweetness, tartness, and cherry flavor. Nondestructive instrumental firmness preceded destructive sensory firmness on the same untreated and GA3-treated cherries in one year when used as a supplementary evaluation. Sensory firmness was consistently higher in GA3 fruit and to a lesser extent in CH2N2 fruit than in CaNH4NO3 and untreated fruit. Instrumental firmness of GA3 fruit did not increase significantly compared with untreated fruit yet instrumental firmness of each treatment correlated relatively well with perceived sensory firmness. Sensory sweetness and cherry flavor scored very similarly, yet both attributes simultaneously varied between treatments across the years. Perceived sensory tartness of treated fruit was variable among years; yet, on average, was rated among treated and untreated fruit as similar. Under the assumption that elevated sensory firmness, sweetness, and cherry flavor intensity reflects improved sweet cherry quality, GA3 fruit were rated of higher quality than untreated fruit given their increased firmness and similar or occasionally elevated sweetness and cherry flavor intensity. CH2N2 fruit maintained quality similar to that of untreated fruit, despite often having marginally higher firmness, due to similar or reduced ratings for sweetness and cherry flavor intensity. Notwithstanding similar firmness between CaNH4NO3 and untreated cherries, sensory quality of CaNH4NO3-treated cherries was reduced due to their often-diminished levels of perceived sweetness and cherry flavor.
Nutrient Release from Controlled-release Fertilizers in Acid Substrate in a Greenhouse Environment: II. Leachate Calcium, Magnesium, Iron, Manganese, Zinc, Copper, and Molybdenum Concentrations
Authors: Blythe Eugene K. , Merhaut Donald J. , Newman Julie P. , Albano Joseph P.
Published: February 2019

Leachate from containerized substrate containing one of four different controlled-release fertilizers (Osmocote, Nutricote, Polyon, or Multicote) were monitored for concentrations of Ca, Mg, Fe, Mn, Zn, Cu, and Mo during a 47-week period. Environmental and cultural practices simulated an unheated greenhouse production program typically used for low-nutrient-requiring crops such as azalea and camellia. Leachate concentrations of all nutrients were relatively high during the first 10 to 20 weeks of the study, and then gradually decreased during the remaining portion of the experiment. Few differences were observed among fertilizer types. Of the elements monitored, only Fe and Mn leachate concentrations were above critical levels specified in the Clean Water Act by the U.S. EPA.