Agrichemical spray drift is an issue of concern for the orcharding industry. Shelterbelts surrounding orchard blocks can significantly reduce spray drift by intercepting droplets from the airflow. At present, there is little information available with which to predict drift deposits downwind, particularly in the case of a fully-sheltered orchard block. In this thesis, we develop a simple mathematical model for the transport of airborne drifting spray droplets, including the effects of droplet evaporation and interception by a shelterbelt. The object is for the model to capture the major features of the droplet transport, yet be simple enough to determine an analytic solution, so that the deposit on the ground may be easily calculated and the effect of parameter variations observed. We model the droplet transport using an advection-dispersion equation, with a trapping term added to represent the shelterbelt. In order to proceed analytically, we discretise the shelterbelt by dividing it into a three-dimensional array of blocks, with the trapping in each block concentrated to the point at its centre. First, we consider the more straightforward case where the droplets do not evaporate; solutions are presented in one, two and three dimensions, along with explicit expressions for the total amount trapped and the deposit on the ground. With evaporation, the model is more difficult to solve analytically, and the solutions obtained are nestled in integral equations which are evaluated numerically. In both cases, examples are presented to show the deposition profile on the ground downwind of the shelterbelt, and the corresponding reduction in deposit from the same scenario without the shelterbelt.

European immigrants introduced orchards to the U.S. in the early 1600s. As they began to establish settlements and migrate west, they brought orchard cultivation with them, creating an extensive network of orchards spread across the U.S. However, over time many of these orchards were lost due to urban development, which is what makes Seattle’s historic orchards significant. Early Seattle settlers planted orchards in the 1800s and early 1900s, and their remnants still exist today, despite urban development. Over the years, many of the orchards have been incorporated onto City Department-owned land, but they have not been maintained to the extent that they could or should be. In the past few years, there has been an interest in rejuvenating Seattle’s historic orchards and planting new ones in order to contribute to the growing local urban agriculture movement. This piece of work is framed around a discussion of the significance of Seattle’s orchards, their significance to the surrounding communities, and how the work accomplished at these sites can become sustainable.

Multiple species of Colletotrichum can cause bitter rot disease of apple, but the identities and relative representation of the species causing the disease in Kentucky are unknown. A total of 475 Colletotrichum isolates were collected from diseased apples in 25 counties and characterized both morphologically and by using various molecular approaches. Four morphotypes corresponded to reported descriptions of bitter rot species. Morphotype 1, distinguished by the production of a pink color on potato dextrose agar (PDA), orange conidial masses, and fusiform spores, was consistent with C. acutatum. Morphotype 2, which produced gray or white mycelial colonies with orange conidial masses and fusiform spores, was also similar to C. acutatum. Morphotype 3 had abundant gray mycelium and rounded spores and was identical to C. gloeosporioides. Morphotype 4 produced ascospores and resembled Glomerella cingulata. Species-specific polymerase chain reaction (PCR) indicated that both Morphotype 1 and Morphotype 2 belonged to the C. acutatum species complex, whereas Morphotype 3 and Morphotype 4 corresponded to the C. gloeosporioides complex. Multigene sequence analyses revealed that sample isolates belonged to several newly erected species within these species complexes. Morphotype 1 was identified as C. fioriniae, which resides within the C. acutatum species complex. Morphotype 2 was identified as C. nymphaeae, which is also a species within the C. acutatum species complex. Some isolates of Morphotype 3 were identified as C. siamense and some as C. theobromicola; both species are grouped within the C. gloeosporioides species complex. Morphotype 4 was identified as C. fructicola, which is also placed within the C. gloeosporioides species complex. C. fioriniae was the most common species causing bitter rot in Kentucky, comprising more than 70% of the isolates. Molecular fingerprinting using random amplified polymorphic DNA (RAPD) suggested that isolates within C. fioriniae belonged to a relatively homogeneous population, while isolates within C. siamense, C. theobromicola and C. fructicola were more diverse. Infectivity tests on detached fruit showed that C. gloeosporioides species-complex isolates were more aggressive than isolates in the C. acutatum species complex. However, isolates within the C. acutatum species complex produced more spores on lesions compared to isolates within the C. gloeosporioides species complex. Aggressiveness varied among individual species within a species complex. C. siamense was the most aggressive species identified in this study. Within the C. acutatum species complex, C. fioriniae was more aggressive than C. nymphaeae, causing larger, deeper lesions. Apple cultivar did not have significant effect on lesion development. However, Colletotrichum species produced more spores on Red Stayman Winesap than on Golden Delicious. Fungicide sensitivity tests revealed that the C. acutatum species complex was more tolerant to thiophanate-methyl, myclobutanil, trifloxystrobin, and captan compared to the C. gloeosporioides species complex. The study also revealed that mycelial growth of C. siamense was more sensitive to tested fungicides compared to C. fructicola and C. theobromicola. These research findings emphasize the importance of accurate identification of Colletotrichum species within each species complex, since they exhibit differences in pathogenicity and fungicide sensitivity.

Tez (Yüksek Lisans) - Süleyman Demirel Üniversitesi, Fen Bilimleri Enstitüsü, Orman Mühendisliği Anabilim Dalı, 2008. / Bibliyografya var.

Thesis (MScAgric)--University of Stellenbosch, 2006. / Bibliography. Also available via the Internet.

Thesis (MScAgric)--University of Stellenbosch, 2007. / ENGLISH ABSTRACT: The macro-element uptake and distribution by higher density central leader ‘Donnarine’ nectarine trees was studied through the sequential excavation of trees. A large portion, 41.5%, of the nitrogen manifested in the new growth from dormancy up to pit-hardening, originated from nitrogen reserves in the permanent structure. The permanent structure was also an important source of phosphorous reserves. Of the phosphorous in the fruit, leaves and new shoots at pit-hardening, 35.0% came from reserves in the permanent structure. Potassium did not act as an important reserve in the nectarine trees and was taken up throughout the season. From pit hardening to harvest the fruit represented the most important sink for potassium. Calcium and magnesium, like potassium, did not play significant roles as reserves in the nectarine tree and must be available for uptake from the beginning of the season for new growth and development as well as fruit quality. The micro-element uptake and distribution was also studied through the sequential excavation of the same ‘Donnarine’ nectarine trees. Little scientific data is available on this topic. Manganese and iron was found to act as important reserves in the tree with 46.2% of manganese and 59.5% of the iron found in the new growth at pithardening coming from reserves translocated from the permanent structure. Zinc and boron reserves also play a role in nectarine trees, but to a lesser extent than manganese and iron. The seasonal mineral nutrient demand of the same ‘Donnarine’ nectarine trees was determined through the sequential excavation of trees and losses and fixation was calculated. Guidelines regarding nutritional requirements per ton of fruit produced per hectare by higher density nectarine orchards are respectively 3.82kg nitrogen, 0.35kg phosphorous, 4.43kg potassium, 1.53kg calcium, 0.52kg magnesium, 32.45g sodium, 9.44g manganese, 37.46g iron, 3.24g copper, 13.95g zinc and 10.52g boron. Sodium is not commonly considered to be essential to higher plants, but was included in the trial. Nutrient solutions with four different EC (electrical conductivity) levels were applied to ‘Donnarine’ nectarine trees under pulsating drip fertigation for three periods of different lengths, before harvest. Raising the nutrient solution EC to positively affect fruit quality is a technique widely utilised in the vegetable industry. This technique did, however, not have similar positive effects on nectarine fruit grown under a pulsating drip fertigation system. Good production practices such as accurate nutrition and irrigation as well as the correct horticultural inputs should be the primary focus of producers who wish to alter or improve the fruit quality of their crop. / AFRIKAANSE OPSOMMING: Voedingbestuur strategieë in nektarien boorde Die makro-element opname en verspreiding deur hoër digtheid sentrale leier ‘Donnarine’ nektarien bome is bestudeer d.m.v. opeenvolgende opgrawings van volledige bome en die ontleding van monsters. ‘n Groot hoeveelheid, 41.5%, van die stikstof wat tydens pitverharding in die nuwe groei teenwoordig was, is d.m.v. translokasie vanuit die permanente struktuur van die boom afkomstig. Die permanente struktuur was ook ‘n belangrike bron van fosfaat reserwes. Teen pitverharding was 35.0% van die fosfaat in die nuwe groei afkomstig vanuit die permanente struktuur. Bevindings het getoon dat kalium nie as ‘n reserwe in die nektarien bome opgetree het nie en dié element is deur die groeiseisoen opgeneem. Vanaf pitverharding tot en met oestyd was die vrugte die sterkste setel van aanvraag vir kalium. Kalsium en magnesium het, soos in die geval van kalium, nie ‘n belangrike rol as reserwe vertolk nie. Beskikbaarheid van hierdie elemente vir opname vanaf die begin van die groeiseisoen is dus baie belangrik vir nuwe groei en ontwikkeling asook vrugkwaliteit. Die mikro-element opname en distribusie van dieselfde ‘Donnarine’ nektarien bome is ook bestudeer d.m.v. opeenvolgende opgrawings en analise van volledige bome. Min wetenskaplike literatuur oor hierdie onderwerp is beskikbaar. Bevindings het getoon dat mangaan asook yster baie belangrike reserwes in die nektarien boom is. Tydens pitverharding was 46.2% van die mangaan en 59.5% van die yster wat in die nuwe groei teenwoordig was, afkomstig vanaf reserwes uit die permanente struktuur van die boom. Verder het sink en boor ook as reserwes opgetree, maar tot ‘n mindere mate as mangaan en yster. Die seisoenale behoeftes aan minerale voeding van dieselfde ‘Donnarine’ nektarien bome is bepaal d.m.v. opeenvolgende opgrawings en analise van volledige bome asook die bepaling van verwyderingsverliese en vaslegging. Voedingsriglyne is vasgestel i.t.v. die hoeveelheid voedingstof wat per hektaar benodig word om een ton nektariens te produseer. Die riglyne is as volg: 3.82kg stikstof, 0.35kg fosfaat, 4.43kg kalium, 1.53kg kalsium, 0.52kg magnesium, 32.45g natrium, 9.44g mangaan, 37.46g yster, 3.24g koper, 13.95g sink en 10.52g boor. Natrium word nie in die algemeen as ‘n essensiële plantvoedingselement beskou nie, maar is by die berekeninge ingesluit. Voedingsoplossing met vier verskillende vlakke van EG (elektriese geleiding) is vir drie periodes van verskillende lengtes aan ‘Donnarine’ nekarien bome toegedien. Die verhoging van die EG van voedingsoplossings ten einde kwaliteit te verbeter is ‘n tegniek wat met groot suskses in die groentbedryf toegepas word. Hierdie tegniek het egter nie soortgelyke positiewe effekte op die nektarien vrugkwaliteit gehad nie. Produsente wat hul vrugkwaliteit wil verbeter behoort primêr te fokus op goeie produksiepraktyke soos akkurate voeding en besproeiing asook die korrekte tuinboukundige insette.

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第20816号 / 農博第2256号 / 新制||農||1055(附属図書館) / 学位論文||H30||N5098(農学部図書室) / 京都大学大学院農学研究科森林科学専攻 / (主査)教授 神﨑 護, 教授 北島 薫, 教授 德地 直子 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DGAM

No description available.

Agrivoltaic (APV) systems, based on the co-location of solar panels and crops, are an innovative solution to land-use conflicts that often arise between agriculture and energy production. Their optimal functioning starts with efficient management and sharing of light between solar panels and underlying plants. This is where tracking systems come into play, as they offer the flexibility needed to strike a balance between energy production and crop growth. This thesis presents several tracking optimization techniques that focus on the availability and distribution of light. To simulate and analyze the performance of these strategies, a simulation model was created, with reference to a Fraunhofer ISE research project in Bavendorf, Germany where semi-transparent solar panels are installed over an apple orchard. The chosen developmental environment was Simtool, a Fraunhofer Python package based on the ray-tracing tool Radiance. Considering the computational cost of the simulation, a Bayesian black-box optimization algorithm was leveraged to relieve the latter from such a computational burden. For the first scenario, the goal was to maximise the radiation reaching solar panels. The algorithm developed, Diffuse-Track Optimization, proved particularly effective during overcast days, allowing daily energy gains of up to 9%. Plants were prioritized in the second scenario, Trees-Track Optimization with the goal of minimising their shading rates, which were seen to fall below 10% despite the presence of the tracking system. Lastly, a compromise between the two objectives was achieved in the final scenario through an overall optimization approach, called APV-Track Optimization. By assigning equal importance to the irradiation reaching trees and that which reaches photovoltaic panels, shading rates of less than 40% can be guaranteed throughout the year, with a reduction of the electrical yield by only 8% compared to backtracking conditions.  The study showcased the potential of the proposed methodology, representing a good starting point to develop holistic optimisations methods that are still lacking in the literature. Future developments will reduce runtime costs, integrate weather forecasts and validate results by means of accurate field measurements. / Agrivoltaiska system (APV), som baseras på samlokalisering av solpaneler och grödor, är en innovativ lösning på de markanvändningskonflikter som ofta uppstår mellan jordbruk och energiproduktion. För att de ska fungera optimalt krävs en effektiv hantering och fördelning av ljuset mellan solpaneler och underliggande växter. Det är här spårningssystem kommer in i bilden, eftersom de erbjuder den flexibilitet som behövs för att hitta en balans mellan energiproduktion och odling av grödor. I denna avhandling presenteras flera optimeringstekniker för spårningssystem som fokuserar på tillgänglighet och fördelning av ljus. För att simulera och analysera hur dessa strategier fungerar skapades en simuleringsmodell med referens till ett forskningsprojekt vid Fraunhofer ISE i Bavendorf, Tyskland, där halvtransparenta solpaneler installerades över en äppelträdgård. Den valda utvecklingsmiljön var Simtool, ett Fraunhofer Python-paket baserat på strålspårningsverktyget Radiance. Med tanke på simuleringens beräkningskostnad användes en Bayesiansk black-box-optimeringsalgoritm för att avlasta den senare från en sådan beräkningsbörda. I det första scenariot var målet att maximera den strålning som nådde solpanelerna. Den utvecklade algoritmen, Diffuse-Track Optimization, visade sig vara särskilt effektiv under mulna dagar och möjliggjorde dagliga energivinster på upp till 9%. Växter prioriterades i det andra scenariot, Trees-Track Optimization, med målet att minimera deras skuggningsgrad, som sjönk under 10% trots närvaron av spårningssystemet. Slutligen uppnåddes en kompromiss mellan de två målen i det slutliga scenariot genomen övergripande optimeringsmetod, kallad APV-Track Optimization. Genom att lägga lika stor vikt vid den strålning som når träden och den som når solcellspanelerna kan en skuggningsgrad på mindre än 40% garanteras under hela året, med en minskning av elutbytet med endast 8% jämfört med förhållanden med backtracking.  Studien visade potentialen hos den föreslagna metoden och utgör en bra utgångspunkt för att utveckla holistiska optimeringsmetoder som fortfarande saknas i litteraturen. Framtida utveckling kommer att minska drifttidskostnaderna, integrera väderprognoser och validera resultaten med hjälp av noggranna fältmätningar.

Apple orchards as social-ecological systems provide high value crops and habitat for a variety of species. Yields are influenced by pest control and pollination services, and profit-oriented management often motivates the use of inputs, e.g., pesticides, to complement or replace these services. This can cause undesirable side-effects on the agroecosystem. Previous research insufficiently considers the interplay of social, including economic, and ecological aspects of orchard management. I present an economic-ecological model integrating ecosystem services from natural enemies of pests and wild pollinators, and the anthropogenic inputs pesticides and honeybees. The value of ecosystem services is approached by service provisioning of resilient systems granted through the availability of habitat for service providing organisms instead of assessing the contribution of individual species. The model identifies profit-maximising combinations of anthropogenic inputs and land for habitat. Adding a social perspective, the findings of the model are complemented with survey data on perceptions and economic preferences of apple growers in Skåne, southernmost Sweden. The study suggests that initial densities of pest natural enemies and wild pollinators create a path-dependency determining profit-maximising strategies. Over time, either high- or low-input management is economically rational, and switching strategies requires time and foregoing profits. The threshold, determining the optimal trajectory towards high- or low-input management, is influenced by prices for pesticides, land and honeybees, pesticide toxicities for pest vs. non-target organisms, beneficial effects of habitat, and the effectivity of honeybees substituting wild pollinators. Individual perceptions, e.g., on the substitutability of wild pollinators, as well as risk and time preferences play a vital role in decision-making of the apple growers. Future research should continue exploring the economic importance of resilience in perennial crops as well as social and economic drivers of integrated pest and pollination management.