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<p>  </p> <p>Environmental conditions, like light quality and herbivory, can induce changes in plant physiology. Light quality can be manipulated using LEDs (light emitting diodes) to improve crop quality and yield in horticultural production. The manipulation of light quality has also been utilized in the management of agricultural insect pests. Previous research has provided evidence that changes in light quality can have effects on the growth and chemistry of cannabis crops (<em>Cannabis spp.</em>). Varieties of cannabis are grown for the production of the valued cannabinoids CBD and THC. Pest of cannabis include herbivorous arthropods that reduce hemp yield and quality. Arthropod herbivory can induce chemical and physical changes in plants. This thesis further investigates the role of light quality on both cannabis biology and the crop-pest interaction between cannabis and the cannabis aphid (<em>Phorodon cannabis</em>). In the experiments described herein, the effects of light quality and <em>P. cannabis </em>herbivory on cannabis were assessed by measuring impact on biomass accumulation, yield, and the production of CBD and THC. The effects of light quality on the life history traits of <em>P. cannabis </em>were also measured. Cannabis grown under red-blue light quality saw a reduction in vegetative growth but no reduction in yield. Light treatments had no measured effect on the concentrations of CBD and THC in the cannabis buds. Aphid herbivory decreased bud yield but increased vegetative growth. Aphid herbivory reduced the concentration of both CBD and THC in cannabis bud tissue. Under blue-rich light quality, <em>P. cannabis </em>experienced higher reproductive rates when compared to red-blue and full-spectrum lighting. </p>

Master of Science / Department of Horticulture, Forestry, and Recreation Resources / Jack D. Fry / Dollar spot, caused by Sclerotinia homoeocarpa F.T. Bennett, and silvery-thread moss (Bryum argenteum Hedw.) are pests affecting creeping bentgrass (Agrostis stolonifera L.) that typically require pesticide inputs. New strategies for pest management may reduce chemical inputs. The objectives of these 2009-2010 field studies were to evaluate: 1) creeping bentgrass cultivars for dollar spot susceptibility; 2) alternative chemical controls for silvery-thread moss; and 3) the response of silvery-thread moss to nitrogen (N) sources. During peak dollar spot development, ‘Declaration’, ‘A-4’, and ‘Crenshaw’ had 7.5, 139.4, and 288.9 infection centers m[superscript]-2 under fairway and 2.1, 27.2, and 106.9 infection centers m[superscript]-2 under putting green conditions, respectively. Two spring and two fall spot applications of sodium or potassium bicarbonate (45 g a.i. L[superscript]-1), premixed essential oil, and broadcast applications of carfentrazone-ethyl at 0.09 kg a.i. ha[superscript]-1 suppressed moss 39% to 55% compared to untreated in 2009. Spot sprays of sodium or potassium bicarbonate, and essential oil, were phytotoxic to creeping bentgrass and required up to 8 or 18 days, respectively, to return to acceptable quality. Fertilization with liquid urea (N at 16.3 kg ha[superscript]-1 biweekly, 210 kg ha[superscript]-1 annually) resulted in 147%, 150%, and 155% more moss than fertilization with IBDU, organic N, and granular urea, respectively, and 156% more moss compared to untreated. Fertilization with urea (liquid or granular) resulted in the best creeping bentgrass color. Averaged across the entire season, plots treated with organic N had unacceptable color in 2009. Nitrogen concentrations in moss tissue ranged from 0.4% to 1.0% and were always significantly lower than N concentrations observed in creeping bentgrass (1.1% to 2.1%), regardless of treatment. In 2010, moss treated with liquid urea had higher tissue N concentrations (1.0%) than untreated moss (0.5%) or that fertilized with IBDU (0.4%). In summary, use of dollar spot-resistant creeping bentgrass cultivars could reduce fungicide requirements. Bicarbonate and essential oil products can reduce moss severity at a similar level to carfentrazone-ethyl, but rates and/or application methods need to be optimized to avoid injury to creeping bentgrass. Applications of liquid urea enhanced moss coverage in creeping bentgrass compared to other N sources.

Master of Science / Department of Communications and Agricultural Education / Lauri M. Baker / Garden centers are facing increasing market pressure from big-box retail stores that offer similar products at more competitive prices but lack a quality produce and exceptional service. In order to differentiate themselves from big-box stores, garden centers must build relationships with their customers which can increase marketing reach. Marketing ability and reach is limiting the expansion of Kansas garden centers which spend the majority of their advertising dollars on traditional media. However, social media can be an effective method for not only understanding consumers but also developing profitable relationships with customers. The purpose of this qualitative study was to explore the perceptions and experiences of stakeholders of metro and non-metro garden centers as they use new media to market their business. Findings indicate garden center stakeholders prefer to use traditional media channels to market to their customers, lack a clear strategy and objectives related to new-media marketing, and are not effectively implementing relationship marketing principles.

Thesis (MScAgric)--University of Stellenbosch, 2005. / ENGLISH ABSTRACT: Phaeomoniella chlamydospora is the main causal organism of Petri disease, which causes severe decline and dieback of young grapevines (1-7 years old) and also predisposes the wood for infection by other pathogens. Knowledge about the epidemiology and especially inoculum sources of this disease is imperative for subsequent development of management strategies. Through isolation studies it was shown that Pa. chlamydospora is mainly distributed through infected propagation material in South Africa. However, the infection pathways and inoculum sources in grapevine nurseries are still unclear. The only existing method to detect this pathogen in various media is by means of isolation onto artificial growth media. This has proven to be problematic since this fungus is extremely slow growing (up to 4 weeks from isolation to identification) and its cultures are often over-grown by co-isolated fungi and bacteria before it can be identified. The aim of this study was (i) to develop a protocol for the molecular detection of Pa. chlamydospora in grapevine wood, and (ii) to use this protocol along with others, to test different samples (water, soil, rootstock and scion cuttings and callusing medium) collected from nurseries in South Africa at different nursery stages for the presence of Pa. chlamydospora. A protocol was developed and validated for the molecular detection of Pa. chlamydospora in grapevine wood. Firstly, several previously published protocols were used to develop a cost-effective and time-efficient DNA extraction method from rootstock pieces of potted grapevines. Subsequently, PCR amplification using species-specific primers (Pch1 and Pch2) was found to be sensitive enough to detect as little as 1 pg of Pa. chlamydospora genomic DNA from grapevine wood. The protocol was validated using various grapevine material from 3 different rootstock cultivars (101-14 Mgt, Ramsey and Richter 99) collected from each of 3 different nurseries, including grapevines that were subjected to hot water treatment. The basal end of the rootstock was parallel analysed for Pa. chlamydospora using isolations onto artificial medium and molecular detection. The identity of PCR products obtained from a subset of samples, that only tested positive for Pa. chlamydospora based on molecular detection, was confirmed to be Pa. chlamydospora specific through restriction digestion with AatII. Molecular detection was found to be considerably more sensitive than isolations, detecting Pa. chlamydospora from samples with positive as well as negative isolations. On average, the molecular technique detected Pa. chlamydospora in 80.9% of the samples, whereas only 24.1% of the samples tested positive for Pa. chlamydospora by means of isolations. Pa. chlamydospora was not isolated from hot water treated samples. The results confirm the importance of hot water treatment for proactive management of Petri disease in grapevine nurseries. However, Pa. chlamydospora DNA was molecularly detected in hot water treated samples in frequencies similar to that detected in non-hot water treated samples. As expected, the DNA in hot water treated plants was not destroyed and could be detected by the developed molecular detection protocol. This is an important consideration when using molecular detection for disease diagnosis or pathogen detection and shows that these methods should be used in conjunction with other diagnostic tools. Most importantly, the DNA extraction protocol was shown to be 10 to 15 times cheaper than commercial DNA extraction kits. Preliminary studies showed that the aforementioned molecular detection technique was not specific and sensitive enough for detection of Pa. chlamydospora in soil and water (unpublished data). Therefore, a one-tube nested-PCR technique was optimised for detecting Pa. chlamydospora in DNA extracted from soil, water, callusing medium and grapevine wood. Rootstock cane sections and soil samples were taking from the mother blocks from several nurseries. Water samples were collected from hydration and fungicide tanks during pre-storage and grafting. Scion and rootstock cuttings were also collected during grafting and soil were collected from the nursery beds prior to planting. The one-tube nested-PCR was sensitive enough to detect as little as 1 fg of Pa. chlamydospora genomic DNA from water and 10 fg from wood, callusing medium and soil. PCR analyses of the different nursery samples revealed the presence of several putative Pa. chlamydospora specific bands (360 bp). Subsequent sequence analyses and/or restriction enzyme digestions of all 360 bp PCR bands confirmed that all bands were Pa. chlamydospora specific, except for five bands obtained from callusing media and one band from water. Considering only Pa. chlamydospora specific PCR bands, the molecular detection technique revealed the presence of Pa. chlamydospora in 25% of rootstock cane sections and 17% of the soil samples collected from mother blocks, 42% of rootstock cuttings collected during grafting, 16% of scion cuttings, 40% of water samples collected after the 12- hour pre-storage hydration period, 67% of water samples collected during grafting and 8% of the callusing medium samples. These media should therefore be considered as potential inoculum sources or infection points of the pathogen during the nursery stages. The results furthermore confirmed previous findings that Pa. chlamydospora is mainly distributed through infected rootstock canes and cuttings. Infected scion cuttings were also shown to be potential carriers of the pathogen. Management strategies should include wound protection of rootstock mother plants, eradicating this pathogen from rootstock-cuttings (e.g. hot water treatment), biological or chemical amendments in the hydration water and callusing medium and wound protection from soil borne infections. / AFRIKAANSE OPSOMMING: Phaeomoniella chlamydospora is die hoof veroorsakende organisme van Petri se siekte wat lei tot die agteruitgang en terugsterwing van jong wingerdplante (1-7 jaar oud) en veroorsaak verhoogde vatbaarheid van hout vir infeksie deur ander patogene. Kennis oor die epidemiologie en veral die inokulumbronne van die siekte is noodsaaklik vir die daaropvolgende ontwikkeling van beheerstrategieë. Isolasies het getoon dat Pa. chlamydospora meestal versprei deur middel van geïnfekteerde voortplantingsmateriaal in Suid-Afrika. Die infeksieweë en inokulumbronne in wingerdkwekerye is egter steeds onbekend. Die enigste bestaande metode vir die opsporing van die patogeen, in verskeie mediums, is deur middel van isolasie op kunsmatige groeimediums. Dit is egter gevind om problematies te wees aangesien die swam uiters stadig groei (dit vat tot 4 weke vanaf isolasie tot identifikasie) en die kulture is telkens oorgroei deur ander organismes voordat identifikasie kan plaasvind. Die doel van die studie was (i) om ‘n protokol te ontwikkel vir die molekulêre opsporing van Pa. chlamydospora in wingerdhout, en (ii) om die protokol te gebruik, saam met ander, om verskillende monsters (water, grond, onderstok- en bostok-ente en kallusmedium) te toets, wat versamel is van kwekerye in Suid- Afrika, tydens verskillende kwekerystadiums, vir die teenwoordigheid van Pa. chlamydospora. ‘n Protokol is ontwikkel en geverifieer vir die molekulêre opsporing van Pa. chlamydospora in wingerdhout. Eerstens is verskeie protokols wat voorheen gepubliseer is, is as grondslag gebruik vir die ontwikkeling van ‘n ekonomiese en tydbesparende DNA ekstraksie protokol. Hierna is PKR (polimerase ketting reaksie) amplifikasie met spesie-spesifieke inleiers (Pch1 en Pch2) gevind om sensitief genoeg te wees om so min as 1 pg van Pa. chlamydospora genomiese DNA van wingerdhout op te spoor. Die protokol is geverifieer deur verskeie wingerdhoutmateriaal van 3 verskillende onderstokkultivars (101-14 Mgt, Ramsey en Richter 99) te gebruik, wat elk versamel is van 3 verskillende kwekerye. ‘n Aantal van die wingerstokke is ook onderwerp aan warmwaterbehandeling. Die basale kant van die onderstok is parallel geanaliseer vir Pa. chlamydospora deur gebruik te maak van isolasies op kunsmatige groeimedium asook molekulêre opsporing. Die identiteit van ‘n submonster van PKR produkte van verskeie monsters, wat slegs positief getoets het vir Pa. chlamydospora met die molekulêre opsporing, is bevestig om Pa. chlamydospora spesifiek te wees. Dit is gedoen deur middel van restriksie ensiem analise met AatII. Molekulêre opsporing is gevind om aansienlik meer sensitief te wees as isolasies, deurdat Pa. chlamydospora opgespoor is van positiewe sowel as negatiewe isolasies. Die molekulêre tegniek het Pa. chlamydospora in ‘n gemiddeld van 80.9% van die monsters opgespoor, terwyl slegs ‘n gemiddeld van 24.1% van die monsters postief getoets het vir Pa. chlamydospora, deur middel van isolasies. Pa. chlamydospora is nie geïsoleer van die monsters wat warmwaterbehandeling ondergaan het nie. Die resultate bevestig hoe belangrik warmwaterbehandeling is vir die proaktiewe beheer van Petri se siekte in wingerdkwekerye. Pa. chlamydospora DNA is met die molekulêre tegniek opgespoor, in warmwaterbehandelde monsters, in getalle wat ooreenstemmend is met die van niewarmwaterbehandelde monsters. Soos verwag, is DNA in warmwaterbehandelde plante nie vernietig nie en kon dit telke male opgespoor word deur die ontwikkelde molekulêre opsporing protokol. Dit is ‘n belangrike feit wat in ag geneem moet word wanneer molekulêre opsporing gebruik word in siekte diagnose en opsporing van patogene en dit is ‘n aanduiding dat die metodes gebruik moet word in samewerking met ander diagnostiese tegnieke. Die DNA ekstraksie protokol het getoon om tot en met 10 tot 15 kere goedkoper te wees as kommersiële DNA ekstraksie pakkette. Voorlopige studies het getoon dat die bogenoemde molekulêre opsporings tegniek nie spesifiek en sensitief genoeg is vir die opsporing van Pa. chlamydospora uit grond en water nie (ongepubliseerde data). Daarom is ‘n enkel-buis geneste-PKR tegniek geoptimiseer vir die opsporing van Pa. chlamydospora DNA wat geëkstraheer is vanaf grond, water, kallusmedium en wingerdhout. Dele van onderstokke en grond monsters is geneem vanaf moederblokke van verskeie kwekerye. Gedurende die voor-opberging en enting periodes is watermonsters versamel vanaf hidrasie en fungisied tenke. Bostok- en onderstokente is ook versamel gedurende enting en grond is versamel vanaf kwekerybeddens net voor uitplanting. Die enkelbuis geneste-PKR was sensitief genoeg om so min as 1 fg van Pa. chlamydospora genomiese DNA vanaf water en 10 fg vanaf hout, kallusmedium en grond op te spoor. PKR analise van die verskillende kwekerymonsters het getoon dat daar ‘n teenwoordigheid is van verskeie putatiewe Pa. chlamydospora spesifieke bande (360 bp). Daaropvolgende analise deur middel van DNA volgordebepaling en restriksie ensiem analise het bevestig dat al die 360 bp PKR bande wel Pa. chlamydospora spesifiek is, behalwe vir vyf bande wat verkry is vanaf kallusmedium en een band verkry vanaf water. As slegs Pa. chlamydospora spesifieke bande in ag geneem word, is daar met molekulêre opsporing die teenwoordigheid van Pa. chlamydospora gevind in 25% van die onderstokke, 17 % van die grond versamel vanaf moederblokke, 42% van die onderstokente versamel tydens enting, 16% van die bostokente, 40% van die watermonsters versamel voor die 12-uur hidrasie periode, 67% van die watermonsters versamel gedurende enting en 8% van die kallusmediummonsters. Hierdie mediums moet dus beskou word as potensiële inokulumbronne of infeksiepunte van die patogeen gedurende die kwekerystadiums. Die resultate bevestig ook verdere bevindinge wat aandui dat Pa. chlamydospora meestal versprei word deur geïnfekteerde onderstokke en ente. Geïnfekteerde bostokente is ook aangedui om potensiële draers van die patogeen te wees. Beheerstrategieë moet dus wondbeskerming van onderstok moederplante insluit, asook uitwissing van die patogeen vanaf onderstokente (bv. warmwaterbehandeling), toediening van biologiese of chemiese stowwe in die hidrasie water en kallusmedium en wondbeskerming teen grondgedraagde infeksies.

Horticulture is a major foreign exchange earner in Kenya and provides employment to approximately 75% of the population. However, the growth of the horticultural industry is constrained by pests such as the leafminer flies, Liriomyza sativae, L. trifolii and L. huidobrensis (Diptera: Agromyzidae). These pests do not only cause damage to crops, but are also tagged as quarantine pests, resulting in export rejections, loss of export markets and consequently loss of revenue to smallholders. The management of leafminers worldwide has commonly relied on the use of chemical insecticides, but due to associated negative effects thereof, biological control using parasitoids and entomopathogenic fungi has been proposed as major components of integrated pest management (IPM) strategies. The indigenous ectoparasitoid Diglyphus isaea and exotic endoparasitoid Phaedrotoma scabriventris are the two key natural enemies being considered. A number of endophytic fungal isolates have been identified with potential for use as biological control agents of pests. Although there have been previous reports on toxicity of fungal endophytes to leafminers, no attempts have been made to exploit them for control of Liriomyza leafminers. The objectives of this study were to investigate the mechanisms by which fungal endophytes control Liriomyza spp., as well as the interactions between these endophytic fungi and the L. huidobrensis, endoparasitoid Phaedrotoma scabriventris and ectoparasitoid Diglyphus isaea. This study showed that under laboratory conditions, while used separately, parasitism rates of L. huidobrensis by D. isaea and P. scabriventris were 63.6 ± 7.7% and 30.4 ± 10.9% respectively and increased to 77.0 ± 5.3% when used simultaneously. In addition, both parasitoids induced leafminer mortality through larval-feeding and stinging. In order to identify and characterize endophytic fungi that could possibly be used for control of these pests, fungi were isolated from the aboveground parts of maize, sorghum, Napier grass, Coleopteran larvae and Busseola fusca pupae. Identified fungi were evaluated endophytically in two host plants species (Phaseolus vulgaris and Vicia faba) through seed inoculation. The fungal isolates that succeeded in colonizing the host plants were all pathogenic to L. huidobrensis, causing 100% mortality within 13.2 ± 0.7-15.0 ± 0.6 days. They were also able to reduce the longevity of the progeny, the number of pupae and adult emergence and survival. In addition, results also showed that endophytically-inoculated and L. huidobrensis-infested V. faba plants had no adverse effects on parasitism rates and life history parameters of P. scabriventris and D. isaea. Bio-prospecting for fungal endophytes in P. vulgaris and V. faba seeds, followed by morphological and molecular identification revealed the presence of various species of fungal entomopathogens, including Beauveria bassiana, Epacris microphylla, Phanerochaete chrysosporium and Metarhizium anisopliae. / PhD (Environmental Sciences), North-West University, Potchefstroom Campus, 2013

Reciprocal plantings of populations of broomsedge, taken from an abandoned strip mine and from an abandoned farm plot in south central Kentucky, on strip mine spoil and abandoned field soil resulted in patterns of populations differentiation. Clonal plantings of populations from strip mine habitats and old field development appeared equal in height and biomass when grown on old field soils in both field trials and growth chamber studies. Populations when planted in strip mine soils in field trials and controlled growth experiments. Later flowering in strip mine populations may be a key to survival strategy in the harsh microclimates of spoil banks. Andropogon virginicus L. may prove to be a significant and economically sound species in reclamation programs.

Master of Science / Department of Horticulture, Forestry & Recreation Resources / Greg Davis / Urban environmental pollution continues to be exacerbated by a number of factors relating to human population growth including sewage discharged directly into the urban rivers designed with concrete-sealed riverfronts. This has left a number of rivers with deteriorated water quality. Where a riverfront could be the highlight and magnet of the city, it may instead become a stain and waste place. In 1969 American landscape planner McHarg proposed the landscape planning theory, “Design with Nature." His primary argument was that natural processes provide self-regulatory functions that need to be reflected in our plans and designs. Ecological design aims include restoring or promoting natural processes and automatic (bio-physical, regenerative, and adaptive) stabilizers. A wide range of scientific knowledge is available to help guide the designer, but designers usually have limited time to complete their designs. Unfortunately, much of this information is diffusely dispersed in research literature and not easily collected and synthesized by the design community. The purpose of this review is to help provide a synthesis of current thought and to help establish the basis for principles that can aid the designer, offering easy-to-understand design guidelines related to the use of aquatic plants in ecological redevelopment along urban riverfronts. This report focuses on using aquatic plants as the main material to help solve two key problems along riverfront developments: water pollution and flooding. As such this report can serve as a guide for the designer helping them to select aquatic plants using an ecological design approach for the redevelopment of urban riverfronts. It also addresses the essential need to adapt designs based on local site problems and requirements. Since this report provides a review and a basis for where to start in designing with aquatic plants in ecological redevelopment of urban waterfronts, it should not be considered as an exclusive source for the designer but rather a complement to local guidelines and information to derive design solutions.

Master of Science / Department of Horticulture, Forestry, and Recreation Resources / Chad T. Miller / Kimberly A. Williams / Intumescences are a physiological disorder characterized by hypertrophy and possibly hyperplasia of plant cells. Many plant species are susceptible to intumescence development, but the specific causative factors remain uncertain. Ultimately, this disorder results in the death of the affected cells. Previous observations and research suggest that the quality and quantity of light to which plants are exposed may be a factor in development of the disorder. The purpose of the first study was to assess the preventive effect of UVB radiation on intumescence development in ornamental sweet potato (Ipomoea batatas). Two sweet potato cultivars, ‘Sidekick Black’ and ‘Ace of Spades,’ were grown under four light treatments of 1) Normal; 2) UVB; 3) UVB-Blocked; 4) Full-Spectrum. The ‘Ace of Spades’ cultivar was highly susceptible to intumescence development, while ‘Sidekick Black’ was much less susceptible to the disorder. For ‘Ace of Spades,’ the addition of UVB radiation significantly reduced the number of leaves affected with intumescences when compared to plants grown under the other light treatments. This study indicates a cultivar-specific effect of UVB light in minimizing intumescence development on ornamental sweet potato, therefore suggesting a potential genetic component in intumescence susceptibility. Many plant species are prone to similar physiological disorders in which lesions develop on the leaf tissue. Nomenclature for such lesions has varied significantly in the literature. Interchangeably using these terms causes confusion as to whether these names refer to the same or different disorders. The objective of the second study was to characterize the development of lesions on ornamental sweet potato (Ipomoea batatas ‘Blackie’), tomato (Solanum lycopersicum ‘Maxifort’) and interspecific geranium (Pelargonium בCaliente Coral’). Light microscopy, field emission scanning electron microscopy (FESEM), and digital photography were used to observe lesion development on each species. Lesions on ornamental sweet potato predominately involved the hypertrophy of the palisade parenchyma through the upper epidermis, while geranium lesions involved the hypertrophy of spongy parenchyma cells restricted by the lower epidermis. Tomato lesions involved both the hypertrophy and hyperplasia of the lower epidermis and spongy parenchyma. Thus, different species possess varied cellular responses when developing lesions due to physiological causes.