Dissertations / Theses on the topic 'Trees in the cities'

Amenity trees provide physical, social and economic benefits to people sharing their environment. To maintain the benefits that many people have come to expect of trees in their urban landscapes, a viable and dynamic tree population is required. To this end it is necessary to plant new trees or replace existing trees when they require removal. The challenge when replacing mature trees is not simply the process of planting a tree when one is removed, but of the continual replacement of the entire tree population in a planned and managed fashion. In urban landscapes this is not a natural process, and human intervention is required.

Thesis (M. L. A.)--University of Hong Kong, 2009.
Includes special report study entitled: 'When nature exploits man-made structures ... ' : a detailed study of wall trees in Hong Kong. Includes bibliographical references. Also available in print.

5 pp.
Water is essential for citrus trees because it is an integral component of the biochemical reactions that occur within the plant, and also because it is the carrier that moves plant nutrients and other substances throughout the tree. This publication examines irrigating citrus trees. Topics include; water stress, estimating tree water use, timing water applications, dealing with salty water, calculating how much water is applied, as well as application methods and mulches. And it also includes a table which can be applied to spreadsheets, to calculate the exact amount of water a citrus tree needs.

3 pp.
Citrus budding is a plant propagation technique that any homeowner can do. Once the technique is learned, homeowners can add citrus tree. This publication addresses the budding techniques of citrus trees. Topics include the preparation prior to budding, selecting budsticks, storing budsticks, selecting and preparing the budding location, cutting the bud, inserting the bud in the t cut, and forcing the bud.

Trees are a valuable asset of our society, but little policy research has been conducted in this area at the university level. The policy in Hong Kong has changed from tree preservation to tree management due to repeated tree collapse incidents that have affected public safety and the harmony and sustainability of the environment and society. The Kingdon and Zahariadis multiple streams approach is found to be the most suitable analytical framework for the analysis of tree management policy in Hong Kong. The problem stream looks at why the problems occur, what they are, the magnitude of change in the conditions and why we need to do something about tree management. The policy stream looks at how to deal with and regulate tree management. The politics stream looks at what is done by whom in tree management policy. Finally, the aforementioned three streams are coupled by policy entrepreneurs using policy output so that the agenda can be set and the policy adopted. The tree management policy in Hong Kong is investigated and analysed through the lens of multiple streams theory and it is hoped that the information in this dissertation can offer a clearer understanding of the policy and its role in creating a better Hong Kong.
published_or_final_version
Public Administration
Master
Master of Public Administration

Orientador: Marta Enokibara
Banca: Norma Regina Truppel Constantino
Banca: Maria Lucia Bressan Pinheiro
Resumo: O botânico brasileiro Frederico Carlos Hoehne (1882-1959) iniciou sua carreira como jardineiro-chefe do Museu Nacional do Rio de Janeiro em 1907. No ano de 1917, ao ser convidado para fundar o Horto Oswaldo Cruz no Instituto Butantã, se muda para São Paulo, onde solidifica sua carreira fundando e dirigindo hortos e instituições de pesquisa até o ano de 1952, quando se aposenta. Hoehne é reconhecido como um grande defensor da natureza e também por sua paixão por orquídeas. Contudo, este trabalho tem como objetivo investigar um aspecto ainda pouco explorado na vasta produção do autor, referente ao seu estudo para a indicação de espécies nativas para a arborização urbana. Publicado em 1944, o livro "Arborização Urbana" foi um dos primeiros a tratar sobre este tema, se aproximando dos manuais de arborização atuais. A investigação sobre quais eram essas espécies, sua relação com as espécies do manual de arborização mais recente da cidade de São Paulo (2015) e a origem das referências que subsidiaram Hoehne a indicar tais espécies foram o fio condutor da pesquisa apoiada nos Relatórios escritos pelo autor nas instituições em que trabalhou. O objetivo específico é verificar a atualidade e a contribuição do botânico para a preservação das árvores nativas e sua difusão no meio urbano.
Abstract: The brazilian botanist Frederico Carlos Hoehne (1882-1959) began his career as head gardener of the National Museum of Rio de Janeiro in 1907. In 1917, when invited to found Horto Oswaldo Cruz in the Butantã Institute, he moves to São Paulo, where he solidifies his career by founding and directing gardens and research institutions until 1952, when he retires. Hoehne is recognized as a great advocate of nature and also for his passion for orchids. However, this work aims to investigate an aspect not much explored in the vast production of the author, about his study for the indication of native species for urban afforestation. Published in 1944, the book "Arborização Urbana" was one of the first to address this issue, approaching the current urban afforestation manuals. The research on these species, their relation to the species of the most recent urban afforestation manual of the city of São Paulo (2015) and the origin of the references that subsidized Hoehne to indicate such species was the guiding line of the research, which relied on Reports written by the author in the institutions that worked. The specific objective is to verify the actuality and the contribution of the botanist for the preservation of the native trees and their diffusion in the urban environment.
Mestre

The effects of high sodium chloride (NaCl) levels on Na and nutrient retention of three soil substrates and on littleleaf linden growth in different soil substrates were studied in the laboratory and the greenhouse, within the framework of a substrate selection program for trees planted in downtown Montreal. In addition, the effects of the structural soil (SS) compaction were studied in the first greenhouse experiment. The first greenhouse experiment was established in a factorial arrangement of four soils x four salt levels in a completely randomized design with five replicates. The four soil types were (1) L with a bulk density (BD) of 1.53 g/cm3, (2) LP with a BD of 1.26 g/cm3, (3) SS with a BD of 1.8 g/cm 3 (SS1.8), and (4) SS with a BD of 2.0 g/cm3 (SS2.0). The second greenhouse experiment had a split plot design. Two fertilization levels (with fertilizer and without fertilizer) were randomly arranged as the main plots on ten benches. Within each main plot, the combinations of three NaCl levels (0, 0.5 and 1.0 g NaCl/kg soil) and three soil substrates (L with a BD of 1.40 g/cm3, LP with a BD of 1.13 g/cm 3 and SS2.0) were randomized in the sub-plots. Results from the laboratory leaching experiment indicated that SS had the fastest Na leaching rate and highest Na loss, while LP retained more Na than SS or L. (Abstract shortened by UMI.)

Trees in natural forests are widely known for their essential contribution to rural livelihoods in developing countries, providing both consumptive and non-consumptive products to rural inhabitants. These benefits are also obtained from trees in urban forests and used by urban households. In the past decades, the role of urban trees to urban livelihoods, municipalities, local and global environment has often been overlooked by researchers and development agencies, and hence are poorly documented, especially in Africa. In South Africa, the increase in urbanisation and urban poverty means many urban residents are expected to be dependent on trees and tree products from homesteads, neighbourhoods and edges of towns. There is however a paucity of literature on the potential of trees in sustaining livelihoods and poverty alleviation in urban areas. This study determined the magnitude and nature of the direct contribution of trees and tree products to local livelihoods in different urban residential areas (informal, Reconstruction and Development Programme (RDP), and township) in three South African towns (Tzaneen, Bela Bela and Zeerust) which cover a rainfall gradient from relatively higher (775 mm p.a.) to low (575 mm p.a.). The results showed that most (90%) households had an interest in planting and managing trees on homesteads, given the high proportion (71%) of residents who had planted trees on their homesteads. The abundance of trees followed the moisture gradient, with Tzaneen having a larger share (46.4%) of trees, followed by Bela Bela (27.5%) and Zeerust (26.1%). Larger plots in the informal residential area accounted for the larger proportion (42.8%) of trees on homesteads, followed by the township (32.9%) and RDP households being the least because they were recently established. Tree density was also higher in the high rainfall town but the pattern did not follow the moisture gradient between Bela Bela and Zeerust due to little rainfall difference. However, tree density across residential areas was similar to the proportion of trees on homesteads in residential areas. The most common tree species were alien, and mainly exotic fruit trees made up two-thirds of the trees encountered. Most households collected various products from urban trees, particularly fuelwood, from edges of towns. This was especially by households with lower cash income. However, fruits were collected from homesteads regardless of the wealth status. Tree products had a significant contribution to the total annual household income, with fuelwood alone contributing up to R5 663 per household per annum, equivalent to two-three month household cash income. Tree products added 20% to total household income, which represents the amount of money households save by collecting tree products for free. Therefore, trees within and around urban areas contribute significantly to livelihoods and reduce poverty in urban areas. There is need therefore to encourage urban residents to plant trees on homesteads and policy makers to come up with policies that promote sustainable harvesting of tree products from areas surrounding urban areas.

The goals of this project were to: (1) combine the ARC/INFO Geographic Information System (GIS) software with the TIGER data files and tree inventory data files, (2) demonstrate GIS as a tool in street tree inventory management, (3) answer a management related question, specifically the identification of dead and hazardous trees within the city, with the use of the GIS tool, and (4) prepare an article based on the project for submission to the Journal of Arboriculture.Dead and hazardous trees located along a city street are a major accident liability to a city. It is vital, for both safety and aesthetic purposes, that a community know the location of dead and hazardous trees. As a management tool the GIS can utilize the inventory data to aid the urban forester in interpreting the urban forest by identifying these tree locations. Through the use of point-in-polygon analysis and choropleth maps, these specific management concerns can be highlighted throughout the city.The power to visually demonstrate certain parts of town with higher concentrations of work needed is one way that GIS can provide the management tools necessary for better care of our urban forests.
Department of Landscape Architecture

Thesis (MScAgric)--University of Stellenbosch, 2002.
ENGLISH ABSTRACT: Daily daylight fertigation regimes (involvinq drip fertigation, on a daily basis, during the daylight hours) are becoming widely used in the South African citrus industry in the endeavor to enhance tree productivity. Such regimes could provide sensitive nutrient and moisture management, reducing plant stress in general as well as the response time to root-directed cultural activities. There is a need to evaluate the efficacy of daily daylight fertigation systems relative to conventional irrigation systems. Standard horticultural evaluation of orchard management practices is very time consuming. We opted for physiological studies comparing plant stress levels, in an attempt to quantify plant performance under each system. Citrus trees under daily daylight fertigation and conventional micro-jet and drip-irrigated regimes were monitored to establish plant stress levels as indicated by sap flow, xylem water potential, stomatal conductance and chlorophyll a fluorescence. Plants under a daily daylight fertigation regime are believed to have good soil water conditions in their rooting volume, and therefore experience negligible baseline levels of stress. The trees do, however, experience midday depression in stomatal conductance, to a lesser degree, but not unlike trees under conventional regimes. It appears as if a larger rooting volume of microjet irrigation regimes enhances recovery from the midday depression. It is recommended that producers optimise productivity during the moming hours, by early irrigation, so that plants can function optimally, whilst environmental conditions are most favourable for high physiological activity. We also assessed the effect of withholding water from trees adapted to a daily daylight fertigation regime to evaluate the risk involved with short-term water deficits in trees adapted to this regime, as well as the usefulness of physiological techniques for identifying water stress. Stomatal conductance and xylem water potential indicated water stress sooner than the other physiological parameters. Citrus trees seem to be relatively insensitive to water deficit stress as measured by sap flow and chlorophyll a fluorescence. Sap flow is buffered by tree capacitance, and although mediated via stomatal conductance, atmospheric conditions and not the soil water content primarily determine it. As daily fertigation is applied to trees under DOF regimes, they exhibit more optimal levels of xylem water potential and stomatal conductance, compared to trees from which water is withheld. Although alleviating it to a degree, daily irrigation did not mitigate the midday depression in these values. Seen over a season, even small enhancements of stomatal conductance (and with it photosynthesis and possibly, growth) and xylem water potential, could incrementally produce higher yields.
AFRIKAANSE OPSOMMING: In die strewe na verhoogde boomproduktiwiteit, word daaglikse sproeibemesting (deur 'n drupbesproeiingsstelsel toegedien tydens die dagligure) al meer algemeen in die Suid Afrikaanse sitrusbedryf gebruik. Hierdie praktyk verminder algemene plantstres deur baie spesifieke voedingsen vogbeheer, en verkort ook die plant se reaksietyd op wortelgerigte bewerkingsaktiwiteite. Dit is nodig om die relatiewe voordeel van daaglikse sproeibemesting teenoor konvensionele besproeiingssisteme te evalueer. Huidige tuinboukundige evaluering van boord-bestuurspraktyke is baie tydrowend. In 'n poging om plantreaksie onder verskillende praktyke te beskryf, het ons besluit om die plantstresvlakke met fisiologiese metodes te vergelyk. Sitrusbome onder daaglikse sproeibemesting, en konvensionele mikro- en drupbesproeiing, is onderskeidelik gemonitor om die plant se stresvlakke vas te stel, soos aangedui deur sapvloei, xileem-waterpotensiaal, stomatale geleiding en chlorofil a f1uoresensie. Die plante onder daaglikse sproeibemesting ondervind lae viakkke van waterstremming, waarskynlik weens hoë grondvogtigheid in die wortelsone. Die bome ondervind wel, soos dié onder konvensionele besproeiing, middagdepressie in stomatale geleiding, hoewel tot 'n mindere mate. Dit blyk asof die groter wortelvolume van mikrospuit besproeide bome die herstel na middagdepressie bespoedig. Produsente word aangeraai om die oggendure optimaal te gebruik deur vroeg te besproei sodat plantproduktiwiteit hoog is terwyl die omgewingsfaktore op hul gunstigste is en wanneer die hoogste fisiologiese aktiwiteit voorkom. Ons het ook die effek van wateronthouding gemeet op die bome wat aangepas is vir daaglikse sproeibemesting. Sodoende is die risiko verbonde aan 'n korttermyn watertekort op hierdie bome ge-evalueer, asook die bruikbaarheid van fisiologiese tegnieke om waterstremming in sitrus te identifiseer. Stomatale geleiding en xileem-waterpotensiaal het waterstremming vroëer aangedui as die ander fisiologiese parameters. Sitrusbome blyk redelik onsensitief te wees teenoor droogtestremming soos gemeet deur sapvloei en chlorofil a fluoresensie. Sapvloei word gebuffer deur boom-kapasitansie, en alhoewel sapvloei gereguleer word deur stomatale geleiding, is dit die atmosferiese toestande (hoofsaaklik dampdruk verskil) wat dit primêr beïnvloed, en nie die grond-water inhoud nie. Omdat bome daagliks sproeibemes word, het hulle meer optimale vlakke van xileemwaterpotensiaal en stomatale geleiding in vergelyking met bome waarvan water weerhou is. Alhoewel daaglikse sproeibemesting die middagdepressie verlaag het, is dit nie daardeur opgelos nie. Oor die typerk van 'n seisoen kan selfs minimale verhogings in stomatale geleiding (en daarmeesaam fotosintese en moontlik groei) en xileem-waterpotensiaal, hoër opbrengste tot gevolg hê.

Neglected mature 'Wichita' pecan trees were rejuvenated using various pruning techniques in 1997. Trees were pruned using proven horticultural techniques which included dehorning (cutting main scaffolds to within 2 feet of trunk) and cutting main scaffolds by 50%. To date the treatments have resulted in an increase in yield when compared to trees that received no pruning. In 1999 the grower has developed an orchard management program conducive to maximum production.

Our climate and our cities are changing. Though their changes are not completely dependent upon one another, there is still a coupling effect between them. This study assesses the role of urban form as it pertains to elements of climate change. It is comprised of two essays intended for publication. The first of these essays addresses the feedbacks between urban form, energy consumption, and rising global temperatures. The second essay looks at one particular factor of urban form--tree type--as it pertains to air pollution and urban heat island mitigation. Both papers use the analytical approaches necessary to answer the questions they pose, not ubiquitous over-generalizing modeling software or methods found often in the literature. As seen in the analyses, this practice--known as geocomputation--allows for a deeper and more accurate description of complex spatial relationships.

Orientador: João Roberto Gomes de Faria
Banca: Maria Solange G. de Fontes
Banca: Lea Cristina Lucas de Souza
Resumo: A arborização de vias urbanas pode se constituir num elemento bastante eficaz na amenização de altas temperaturas na camada intraurbana, através de mecanismos de sombreamento e evapotranspiração. Entretanto, entre os variados tipos de espécies arbóreas, quais seriam as mais indicadas para utilização na arborização das vias, a fim de mitigar a temperatura do ar no ambiente urbano? A utilização de ferramentas computacionais é uma alternativa para análise desta questão, tendo em vista que, o uso destes programas auxilia as pesquisas na área de planejamento e avaliação do ambiente construído, por meio da simulação de variados cenários. Um programa bastante utilizado para estudos de interação entre a vegetação e microclimas urbanos é o ENVI-Met, o qual, no entanto, não contém em seu banco de dados, parâmetros relativos a espécies brasileiras, em particular as de cerrado, o que pode gerar cenários microclimáticos incorretos. O objetivo desta pesquisa é propor um método para avaliação do potencial de sombreamento de espécies usadas em arborização de vias urbanas. Para tanto, foram realizados medições de radiação solar incidente sob copas de algumas espécies, usadas no sombreamento de vias urbanas da cidade de Bauru (SP), cujos resultados foram comparados com os parâmetros das mesmas espécies simulados pelo ENVI-Met. A partir do tratamento dos dados foi gerada uma ferramenta, através da qual é possível extrapolar os resultados para escolha de outras espécies. Assim, espera-se que est... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The afforestation of the urban streets can be a very effective element in the mitigation of high temperatures in urban layer through shading mechanisms and evapotranspiration. However, among the various types of tree species, which are the best indicated for use in street afforestation, to mitigate the air temperature in the urban environment? The use of computational tools would be an alternative to analyze this question, given that the use of these programs help in the research on planning and evaluation of the built environment through the simulation of various scenarios. A program widely used to study the interaction between urban vegetation and microclimates is the ENVI-Met, which, however, does not contain parameters in your database relating to brazilians species, particularly the cerrado species, which can create incorrect microclimatic scenarios. The aims of this research is to propose a method to evaluation of potencial shading of species used in afforestation of urban streets. For that, radiation measurements were performed in incident solar canopies of some species used in shading urban streets of the city of Bauru (SP), whose results were compared with the parameters of the same species simulated by ENVI-Met. From the processing, a tool was generated through which it is possible to extrapolate the results to select other species. Thus, it is expected that this method contributes to the indication of species that contain potential for mitigating the air temperatur... (Complete abstract click electronic access below)
Mestre

Using portable sap flow sensors, the onset and volume of sap moving up the branches of grapefruit (Citrus Paradisi Macfadyen) trees was monitored on an hourly basis. Reference evapotranspiration (ETo) data was obtained from The Arizona Meteorological Network (AZMET). Crop evapotranspiration (ETc) was estimated from soil moisture measurements using a neutron probe. The threshold temperature limits were delineated from an evaluation of the hourly sap flow responses to cold winter and extreme summer temperatures. The heat based crop curve was derived from a correlation of the crop coefficients with heat unit over one crop year. The heat based crop coefficients were found to be similar to crop coefficients derived by other researchers.

In the face of rapid urbanization and global climate change, urban trees and green spaces (UTGS) can contribute to the welfare of people and the urban environment. Urban trees and green spaces can assist to address urbanization challenges related to environmental degradation. While functions of UTGS have been well documented in the developed world, they have not yet received full attention in much of sub-Saharan Africa. Consequently, UTGS are under threat from urban development and fragmentation. Notably, the problems associated with UTGS also fall into the governance realm and indications are that poor governance and management of UTGS can negatively influence the potential benefits of UTGS to local people and the environment. This formed a basis for this research. The main objective of the study was to determine the current governance and management approaches to UTGS in South Africa. Through document search and review, the study determined the governance institutions influencing UTGS at national level and at provincial level (in the Limpopo and Eastern Cape Provinces). Face-to-face and online survey methods were used to determine the extent to which 28 local municipalities had adopted planned, systematic and integrated management of UTGS. The snowball approach was used to determine the key actors involved in UTGS activities and interviews were conducted to establish the roles and capabilities of these actors. A total of 540 household interviews were conducted to determine the institutional factors influencing local peoples’ ability to access, plant and use UTGS. The findings of the study showed that UTGS have not been adequately covered in existing governance institutions and practice at national and provincial levels. Local government municipalities were not managing their UTGS in a planned or systematic manner due to constraining factors such as insufficient funds, insufficient personnel, lack of equipment and lack of political support. Only 7.1 % of the surveyed municipalities had an urban tree management plan and an estimate of the urban tree stock; 32.1 % had tree policies; 28.6 % had tree bylaws; 21.4 % had tree planting schedules; 10.7 % had tree maintenance schedules and only 3.6 % had tree inspection schedules. Key actors involved in UTGS activities differed among levels of government. The actors included national and provincial government departments, local government municipalities, Non-Governmental Organizations, private sector companies and local volunteers. Most of the actors, however, either planted trees or provided tree seedlings to municipalities and the local people. Tenure security was a key institutional factor affecting peoples’ ability to plant, use or even remove trees from their residential plots. The same applied to trees in the streets and public parks. Whereas most respondents did not require permission to plant (79.8 %) or remove (75 %) trees on their residential plots, a majority of them required permission to plant and remove trees from streets (over 70 %) and public parks (over 80 %). However, with regard to planting and removing urban trees in public open spaces, 54% of the respondents indicated that permission was not required suggesting a lack of clarity among local residents on the issue. Overall, the findings of this study indicate that there is no political recognition and support for UTGS at almost all levels of government. This has resulted in the lack of incorporation of UTGS in urban planning and development and has caused UTGS to receive limited funding to permit planned and systematic management. Given the current rates of urbanization and urban development, the lowly prioritised UTGS are vulnerable to exploitation. To conserve UTGS and promote their potential contribution to local people and the environment, UTGS must be recognized and placed on political and development agendas. There is a need to develop national guidelines for UTGS management, assess the extent of the urban forest resource in local municipalities, clearly define the roles and capabilities of different actors, integrate UTGS in the urban planning and development system, and most of all seek to involve the local people in overall management and governance of UTGS.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Architecture, 2010.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 101-103).
A study was carried out to develop a typology of urban metabolic (or resource consumption) profiles for 155 globally representative cities. Classification tree analysis was used to develop a model for determining how certain predictor (or independent) variables are related to levels of resource consumption. These predictor variables are: climate, city GDP, population, and population density. Classification trees and their corresponding decision rules were produced for the following major categories of material and energy resources: Total Energy, Electricity, Fossil fuels, Industrial Minerals & Ores, Construction Minerals, Biomass, Water, and Total Domestic Material Consumption. A tree was also generated for carbon dioxide emissions. Data at the city level was insufficient to include municipal solid waste generation in the analysis. Beyond just providing insight into the effects of the predictor variables on the consumption of different types of resources, the classification trees can also be used to predict consumption levels for cities that were not used in the model training data set. Urban metabolic profiles were also developed for each of the 155 cities, resulting in 15 metabolic types containing cities with identical or almost identical levels of consumption for all of the 8 resources and identical levels of carbon dioxide emissions. The important drivers of the differences in profile for each type include the dominant industries in the cities, as well as the presence of abundant natural resources in the countries in which the cities are the main economic centers.
by Artessa Niccola D. Saldivar-Sali.
S.M.

'Newhall' navel oranges on 'Carrizo' rootstock were planted in Mar. 1997 at the Citrus Agricultural Center. The objectives of this experiment were to i) determine the effects of N rate and fertigation frequency for microsprinkler-irrigated navel oranges on tree N status, and crop yield and quality; and ii) develop Best Management Practices which promote optimum tree growth and production while minimizing nitrate leaching. The trees are equipped with a microsprinkler irrigation system. The experiment is a randomized complete block factorial with N rates of 0, 0.15, 0.30, and 0.45 lb N/tree/year, and fertigation frequencies of weekly, monthly, and three times per year. Unfertilized control trees are also included in the experimental design. Each of the ten treatments is replicated five times. The trees were harvested in Jan. 2002. Fruit were processed through an automatic fruit sizer, and fruit from each plot were further evaluated for fruit quality. Leaf N concentration was responsive to N rate, but not to fertigation frequency. Leaf N in all fertilized plots was above tissue critical levels. Fruit yield in fertilized plots was higher than in unfertilized plots, but, in fertilized treatments, there was no significant effect of N rate or fertigation frequency on fruit yield or quality.

Studies were conducted to evaluate potential chemical disease management tools for Alternaria fruit rot on navel oranges and Coniophora brown wood rot on lemon trees, to investigate the possible effect of branch diameter on development of Coniophora wood rot on lemon trees and to summarize our evaluations of citrus rootstocks with respect to relative resistance to root rot and stem canker development when challenged with Phytophthora citrophthora and P. parasitica. We were unable to reduce the level of Alternaria fruit rot on navel oranges with single applications of Abound or copper hydroxide following significant rainfall events. Wood decay in lemon branches inoculated with Coniophora eremophila was significantly suppressed by Abound and a thick formulation of sodium tetrathiocarbonate. The degree of Coniophora brown wood rot in lemon branches of different diameters was variable, although the level of disease in 10 mm diameter branches was significantly smaller than the amount of wood decay in 30 mm diameter branches. Root loss due to Phytophthora citrophthora and P. parasitica in Citrus macrophylla, rough lemon, C. volkameriana and Troyer citrange was lower than most of the 36 different rootstocks tested. On the other hand, root loss on Carrizo citrange, C-35 citrange and sour orange was among the higher values of disease recorded. Stem canker development due to both species of Phytophthora on Troyer citrange, Carrizo citrange, sour orange and Citrus macrophylla was lower than most of the 36 rootstocks tested. Stem cankers on rough lemon and Citrus volkameriana were among the higher values of disease recorded.

Microsprinkler irrigation offers excellent flexibility for site-specific management of water and nitrogen inputs for citrus orchards in the southwestern United States. Escalating water costs, declining water availability, and increasing regulation of nitrogen (N) fertilizer use are causing growers to adopt practices to improve water and N use efficiency. 'Newhall' navels on 'Carrizo' rootstock were planted in Jan. 1997 and an experiment was initiated. This experiment was continued during 1999. The objective of the experiment was to develop appropriate management guidelines for N fertigation of 3-4 year old microsprinkler-irrigated navel orange trees. Treatments were factorial combinations of three N rates (0.15, 0.30, 0.45 lb N tree⁻¹ yr⁻¹) and three fertigation frequencies (3x/year, monthly, weekly). An untreated control was included. Trunk diameter was not responsive to N rate or fertigation frequency. Leaf N in all treatments, even controls, remained above the critical level (2.5%). However, at each N rate leaf N was highest with the weekly fertigation frequency. Nitrate analyses of soil samples indicate that nitrate leaching was highest with the highest N rate and 3x/year fertigation. Frequent fertigation is recommended because it results in higher leaf N and less nitrate leaching.

Thesis (MSc)--Stellenbosch University, 2000.
Full text to be digitised and attached to bibliographic record.
ENGLISH ABSTRACT: Enhancement of vegetative growth in young citrus plantings The establishment of citrus involves high input costs, with break-even usually only attained after six years, making early returns imperative for economic survival. Early production is inseparably associated with good growth of the trees in the non-bearing years. In cool and cold production regions, coupled with a high frequency of wind, the initial tree growth is unsatisfactory. Trials were conducted to evaluate the effect of foliar application of Progibb® (GA3), Promalin'" (G~+7 + BA), Kelpak® (seaweed extract containing auxins and cytokinins) and soil applications of Temik® (aldicarb) as a means to promote vegetative growth. GA3 and/or aldicarb significantly increased tree height, without increasing the stem diameter in comparison to the control trees on 'Eureka' lemon, but not on 'Lisbon' lemon. G~+7 + BA or Kelpak® treatments did not have an effect on tree growth or fresh weight distribution. In conclusion, growth stimulation by GA3 and/or aldicarb could lead to quicker filling of the allotted space, and consequently higher, earlier yields, but further trials are required to verify these results. Insufficient carbohydrate and nitrogen reserves are often implicated in poor establishment performance of nursery trees. The effect of tree size at planting and different topping heights on early growth in the field were evaluated; also the physical and chemical profile of tall nursery whip trees were quantified. Significant correlations were found between the initial stem diameter and final stem diameter and initial tree height and final tree height at the end of the first growing season. Stem diameter increase was significantly reduced in topped trees relative to untopped trees. Roots comprised approximately 22%, and the aboveground portion about 78% of total dry weight. Roots nearly always contained higher concentrations of carbohydrates and nitrogen reserves. However, the aboveground sections, comprising a higher proportion of total dry weight, contained more than two thirds of total carbohydrates and nitrogen reserves. Topping of nursery whip trees at 60 cm aboveground thus would result in a loss of 33 to 37% dry matter, 29 to 33% carbohydrates and 37 to 46% nitrogen. Therefore, planting large, untopped nursery trees enhance initial tree growth in the orchard. The use of well-branched nursery trees for orchard planting can shorten the time to commercial fruit production. Citrus nursery trees do not develop lateral shoots adequately in the nursery or in the field and therefore necessitate various branch induction techniques. Two trials on newly-planted (one or five months after planting) trees were conducted to evaluate various branch induction techniques, viz., girdling, Promalin® (G~+7 + BA) (at 1000 or 2000 mg/I) and/or leaf removal and notching either to individual buds or the whole trees. The first trial, on l-month-old trees did not yield significant results. In the second trial, notching and girdling significantly increased the number and total length of lateral branches, but notching was the most effective technique. As the first trial, on the very young trees, yielded no significant results, it seems that trees have to be well established before they will respond. In young, non-oearing trees a lot of energy is invested in the flowering process, which results in an inhibition of vegetative growth. Gibberellic acid (GA3) and heavy mineral oil (Bac-oil) treatments, either individually or in combination, applied during early winter were evaluated as a means to reduce flowering levels in young nonbearing citrus trees. GA3 and mineral oil either separately or in combination were sprayed from April to July to the whole tree. GA3 and mineral oil either individually or in combination applied late in May to late June markedly reduced flowering. GA3 application in mid April had a minimal effect on flowering levels. Peak responses to GA3 coincided with a significant reduction in bud sprouting. Although optimum application time proved to be around May to July, this time is likely to vary from year to year depending on the influence of the prevailing temperature and other climatic conditions. The winter application of GA3, specifically, and possibly in combination with mineral oil to inhibit flowering and early vegetative growth may be utilised commercially. However, response may vary dramatically from season to season. Effect of time of application and concentration of 2,4-dichlorophenoxypropionic acid (2,4-DP) and l-naphthaleneacetic acid (NAA) as potential fruit thinning agents to reduce fruit set soon after flowering and enhance vegetative growth were evaluated over a two year period. 2,4-DP at 150 and 300 mg/I and NAA at 200 and 400 mg/! were sprayed on 2- and 4-year-old 'Mihowase' Satsuma, as well as on 2-year-old 'Marisol', 'Nules' and 'Oroval' Clementine trees at two times (late October and early November). The higher concentration of 2,4-DP and NAA generally did not result in increased fruit abscission in the first year. However, in the case of 2,4-DP the higher concentration resulted in stronger thinning in the second year. 2,4-DP and NAA can be used as potential fruit thinning agents to reduce fruit set on young non-bearing trees.
AFRIKAANSE OPSOMMING: Verbetering van vegetatiewe groeie by jong sitrus-aanplantings Die vestiging van sitrus behels hoë insetkoste en die gelykbreekpunt word gewoonlik eers na ses jaar bereik. Vroë opbrengste is dus noodsaaklik vir ekonomiese oorlewing. In koel en koue produksie-areas, met baie wind, is die aanvanklike boomgroei onvoldoende. Studies is uitgevoer om die effek van blaarbespuitings van Progibb'" (GA3), Promalin® (G~+7 + BA), Kelpak (seewier-ekstrak wat ouksien en sitokiniene bevat) en grondtoedienings van Temik® (aldicarb), as metodes om vegetatiewe groei te verbeter te evalueer. GA3 en/of aldicarb het boornhoogte betekenisvol laat toeneem, sonder om stamdeursnit te bevoordeel op 'Eureka' suurlemoen, maar nie op 'Lisbon' suurlemoen nie. G~+7 + BA of Kelpak'" behandelings het geen effek op boomgroei of varsmassa-verspreiding gehad nie. Groeistimulasie deur GA3 en/of Aldicarb kan lei tot vinniger vul van spasie, en hoër en vroeër oeste, maar verdere studies is nodig om die resultate te bevestig. Onvoldoende koolhidraat- en stikstofreserwes word dikwels gekoppel aan swak vestigingsprestasie van kwekerybome. Die effek van boomgrootte by planttyd en verskillende tophoogtes op vroeë groei in die veld is geëvalueer; die fisiese en chemiese profiel van lang ongetopte kwekerybome is ook gekwantifiseer. Betekenisvolle korrelasies is gevind tussen die aanvanklike stamdeursnit en en finale stamdeursnit en tussen aanvanklike boomhoogte en finale boomhoogte aan die einde van die eerste groeiseisoen. Stamdeursnit-toenarne is betekenisvol verminder in getopte bome relatief tot ongetopte bome. Wortels het uit ongeveer 22% en die bogrondse porsie ongeveer 78% van die totale droë massa bestaan. Wortels het bykans altyd hoër konsentrasies koolhidrate- en stikstofreserwes bevat. Die bogrondse gedeeltes, wat ook 'n hoër proporsie van die totale droë massa bevat, het meer as twee derdes van die totale koolhidraat en stikstofreserwes. Die top van kwekerybome op 60 cm bo die grond sal lei tot 'n verlies van 33 tot 37% droë massa, 29 tot 33% koolhidrate en 37 tot 46% stikstof. Dus, die plant van groot, ongetopte kwekerybome sal die aanvanklike boomgroei in die boord verbeter. Die gebruik van goedvertakte kwekerybome by planttyd kan die tyd tot komrnersieële vrugteproduksie verkort. Sitrus-kwekerybome gee nie voldoende laterale vertakking in die kwekery of in die boord nie. Twee studies op pas-aangeplante bome (een en vyf maande na plant) is uitgevoer om verskillende tegnieke om laterale lootgroei te stimuleer te evalueer, nl. Promalin® (G~+7 + BA) (teen 1000 of 2000 mg/I) en/of blaarverwydering, en die maak van kerfies op individuele knoppe of op bome as geheel. In die eerste studie, op die een-maand-oue bome, is geen betekenisvolle resultate verkry nie. In die tweede studie het kerfies en ringelering die hoeveelheid en lengte van laterale takke betekenisvol vermeerder, maar kerfies was meer effektief. Die bome moet egter blykbaar goed gevestig wees voor dit reageer. In jong, nie-draende bome word baie energie gebruik in die blomproses en dit lei tot die inhibisie van vegetatiewe groei. Gibberelliensuur (GA3 ) en 'n swaar mineralolie (Bac-oil) wat individueel of in kombinasie toegedien is tydens die vroeë winter is geëvalueer as 'n tegniek om blomvlakke in jong nie-draende sitrusbome te verminder. GA3 en minerale olie individueel of in kombinasie, is gespuit vanaf April tot Julie op die bome as geheel. GA3 en minerale olie toegedien individueel of in kombinasie laat in Mei tot Junie het blomvlakke verminder. GA3 toegedien in middel April het 'n minimale effek gehad. Die beste reaksie op GA3 het saamgeval met 'n betekenisvolle vermindering in die bot van knoppe. Alhoewel die optimum tyd van toediening rondom Mei tot Julie is, mag hierdie tyd wissel van jaar tot jaar afhangende van die effek van heersende temperature en ander klimaatstoestande. Die wintertoediening van GA3, spesifiek en moontlik in kombinase met minerale olie om blomvlakke en vroeë vegetatiewe groei te verminder kan kommersieel gebruik word. Die reaksie op hierdie behandelings mag egter drasties wissel van seisoen tot seisoen. Die effek van die tyd van toediening en konsentrasie van 2,4- dichlorofenoksipropioonsuur (2,4-DP) en 1-naftaleenasynsuur (NAA) as potensiële vruguitdunagente om vrugset kort na blom totaal te verminder en om vegetatiewe groei te verbeter, is geëvalueer oor 'n twee-jaarperiode. 2,4-DP teen 150 en 300 mg/l en NAA teen 200 en 400 mg/l is gespuit op 2- en 4-jaaroue 'Mihowase' Satsuma, en ook op 2-jaaroue 'Marisoi', 'Nules' en 'Oroval' Clementines op twee tye (laat Oktober en vroeg November). Die hoër konsentrasies van 2,4-DP en NAA het oor die algemeen nie gelei tot 'n verhoging in vrugafsnoering in die eeste jaar nie. Met 2,4- DP het die hoër konsentrasie gelei tot strawwer uitdunning in die tweede jaar. 2,4-DP en NAA kan as potensiële vruguitdunagente op jong, nie-draende bome gebruik word.

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Lisbon lemons were treated with N levels ranging from 0.5 to 3.0 lbs. N per tree annually. Fourth–season yield results from the trial show significant effects of the treatments upon overall yield and leaf N concentrations, but no effect upon fruit packout. Treatments did lead to a significant effect upon leaf nutrient concentration. Total cumulative yields from 2008 to 2012 (not including the freeze-affected 2011-12 season) were significantly affected by the treatments. Trees treated annually with 2.0 lbs N had the greatest yield, which represented a 12% increase over the yield of trees treated with just 0.5 lbs. N annually.

An attempt was made in 1997 to rejuvenate neglected, mature 'Wichita' pecan trees in a commercial Pinal County grove by applying two types of heading back pruning cuts. The treatments were applied during the dormant season prior to the growing season. The trees were pruned using proven horticultural techniques which included dehorning (cutting main scaffolds to within 2 feet of the trunk) and cutting main scaffolds by 50%. After four years of data, the trees receiving no pruning treatments are producing as well or better than trees to which the pruning treatments were applied. The data suggests that a return to normal irrigation and fertilization practices alone will return neglected, water-stressed trees to normal productivity as early as trees that have been headed-back.

A arborização viária é um importante elemento ambiental que mitiga os efeitos que o processo de urbanização causa sobre o ambiente. São vários os fatores que se relacionam ao bom desenvolvimento das árvores nas cidades, entre os quais está o gerenciamento pelo poder público, a percepção dos moradores e as condições ambientais em que estão se desenvolvendo as espécies, principalmente as condições do solo. Assim, o presente trabalho teve como objetivo avaliar relações entre o solo, os moradores e as espécies arbóreas implicadas na arborização urbana no município de Pato Branco. Para tanto, delimitou-se como área de estudo cinco bairros com diferentes características de localização e renda no município: Centro, La Salle, Pinheiros, Aeroporto e Veneza. As espécies estudadas foram Lagerstroemia indica L. (extremosa), Schinus molle L. (aroeira), e Bauhinia variegata L. (pata-de-vaca), escolhidas por sua representatividade na arborização da cidade. Avaliou-se o solo utilizado por 114 indivíduos arbóreos nos cinco bairros e foram aplicados 123 questionários semi estruturados a fim de entender como os moradores desses bairros percebem a arborização urbana. Os resultados da pesquisa indicam que há uma grande variabilidade de características dos solos estudados, os quais apresentam incorporação de materiais antrópicos, inversão de horizontes e ausência de camada orgânica em decomposição. Os resultados de granulometria revelaram que apesar da variabilidade de texturas nos pontos avaliados, a maioria dos solos analisados se enquadra na classe textural muito argilosa ou argilosa. O processo de urbanização da cidade de Pato Branco alterou substancialmente as propriedades químicas dos solos das espécies estudadas, sendo que a maioria apresentou relativo enriquecimento em bases trocáveis, o que antagoniza com a usual baixa fertilidade natural dos solos de Pato Branco. Também houve diferenças químicas quanto aos solos impermeabilizados pelo pavimento e não impermeabilizados, sendo que solos impermeabilizados apresentaram menores valores de matéria orgânica e maiores valores de Ca e pH. Os solos do bairro Centro parecem ser os mais alterados pelo processo de urbanização, sendo esse o bairro onde há maior porcentagem de areia adicionada ao solo, maior impermeabilização e quantidade de materiais advindos da construção civil. Quanto à percepção dos moradores, de forma geral os entrevistados parecem reconhecer a importância e as funções da arborização urbana. Entre os problemas percebidos pelos sujeitos da pesquisa, muitos são de ordem técnica e poderiam ser evitados através de um planejamento eficiente. Outros problemas percebidos são de ordem cultural, mais complexos e de difícil resolução. Os munícipes preferem principalmente as espécies que apresentam atrativos como floradas exuberantes e parecem valorizar as árvores que eles próprios escolheram para ter em frente às suas casas. Nesse sentido, é importante que as estratégias adotadas pelo poder público se ajustem às necessidades locais, preservem aspectos culturais, e contemplem, além dos aspectos técnicos relacionados à arborização, outros 9 aspectos de caráter mais lúdico, que atraiam e estimulem a população a se comprometerem com a mesma.
The street forestation is an important environmental element that mitigates the effects which the process of urbanization on the environment causes. There are various factors that relate to the good development of trees in cities; among them are the management by the government, the residents’ perception and the environmental conditions in which the species are evolving, especially soil conditions. Thus, the present study aimed to evaluate relationships between soil, residents and the arboreal species regarding the urban forestry in Pato Branco. Therefore, it was delimited as study area five neighborhoods with different characteristics of location and income in the county: Centro, La Salle, Pinheiros, Aeroporto e Veneza. Lagerstroemia indica L. (crape myrtle), Schinus molle L. (california pepper tree), and Bauhinia variegata L. (orchid tree) were the species studied, chosen by their representation in the forestation of the city. It was evaluated the soil used by 114 tree individuals in the five neighborhoods and 123 semi-structured questionnaires were administered in order to understand how the residents of these neighborhoods perceive the urban forestation. The survey results indicate that there is a great variability concerning the characteristics of the soils studied which present incorporation of anthropogenic materials, inversion of horizons and absence of decaying organic layer. The results of sieve analysis showed that despite the variability of textures in evaluated points, most soils analyzed fit in the texture class of very clayey or loamy. The urbanization process in the city of Pato Branco has fundamentally altered the chemical properties of soils of the studied species, since most of them showed relative enrichment in exchangeable bases, which antagonizes with the low natural fertility of soils in Pato Branco. There were also chemical differences regarding the impermeable soils by pavement and the ones not impermeable, the impermeable soils presented lower levels of organic matter and higher values of Ca and pH. The soils in the center area seem to be the most affected by the urbanization process, where there is a higher percentage of sand added to the soil, and greater amount of waterproofing materials coming from civil construction. Regarding the perception of residents, in general the interviewees seem to recognize the importance and function of urban forestation. Among the problems perceived by the research subjects, many are technical in nature and could be avoided through an efficient planning. Other observed problems are cultural, more complex and difficult to solve. Residents prefer mainly the species that have attractive such as exuberant blooms and they seem to appreciate trees that they chose by themselves to have in front of their homes. Therefore, it is important to adjust the strategies adopted by the government to the local needs, preserve the cultural aspects, and contemplate besides the technical aspects related to forestation, other aspects in a ludic way, to attract and encourage people to commit themselves with forestation.

This experiment was established in January 2000 in a block of ‘Washington’ navel orange trees at Verde Growers, Stanfield, AZ. Treatments included: normal grower practice, winter low biuret (LB) urea application, summer LB urea application, winter LB urea application plus winter and spring potassium phosphite, winter LB urea application plus summer potassium phosphite, and normal grower practice plus spring potassium phosphite. Each treatment was applied to approximately four acres of trees. For 2000-01, yields ranged from 40 to 45 lbs. per tree, and there was no effect of treatments upon total yield, and only slight effect upon fruit size, grade and quality. For 2001-02, there was a slight effect of treatment upon yield as LB urea led to improved yield, while potassium phosphite led to reduced yield. Normal grower practice was intermediate between these two extremes. For 2002-03, we noted a large increase in yield, however the yield data was lost when the block was inadvertently harvested. For 2005, there was no effect of treatments upon total yield.