Good grapes are required to make good wine. Quality wines start in quality vineyards. Vineyard design, installation, and operation, including site location, trellis options, vine selection, and canopy management, along with when to harvest are discussed. While winemaking is the final phase in the pursuit of the winemaker's passion, it is but a simple formula. The beginning of a good wine is in a good vineyard. This study includes a financial projection for a 10-acre vineyard as well as for starting an onsite, complementary sized winery. Even though many small-to-medium vineyards-to-wineries have started over the last decade, the reason to enter into this type of business is not profit, but passion. Profits are relatively small for the time and labor investment, but the unique wine creations that result are amazing, for the winemaker and the one who enjoys the result.

The natural infestation level for 1985 of the Japanese beetle, Popillia japonica Newman, in the Shenandoah Valley of Virginia failed to reduce berry quality, yield or shoot growth in a commercial vineyard. Intensive postveraison foliage feeding by Japanese beetle resulted 1n fruit with lower soluble solids and higher total titratable acidity at harvest, but did not affect pH, sugar per berry, berry weight, yield, leaves per vine or shoot length. Intensive previraison feeding also resulted in fruit with higher total titratable acidity. All other parameters were unaffected. In a separate experiment with 0, 10, 20, and 33% leaf removal, no relationship was shown between leaf area loss and soluble solids, total titratable acidity or pH. Data from one season of damage by the beetle indicate that control measures may not be warranted in some years. In a third experiment, grape leaves on potted vines were artificially damaged by removing leaf disks with a paper punch. The leaves showed an increased loss of efficiency (measured in net photosynthesis, Pn) for the remaining tissue as leaf area loss (LAL) increased. This loss of efficiency in the remaining leaf area at low levels of damage was more pronounced after 12 days than after either 1 or 5 days. The additive effect on Pn of both LAL and lowered efficiency predicted the total shutdown of Pn at 60% damage at 1 and 5 days after treatment, but not at 12 days. / Master of Science

Vineyard management strategies, including vineyard floor management and crop level management, can be used to influence vine vigor and fruit composition. Two studies were conducted to evaluate the impact of these practices on Pinot Noir in Oregon's Willamette Valley. Managing crop levels is common in cool climate vineyard production though it is a costly practice. With economic pressures, the premium winegrape industry is questioning whether they can reduce production costs and increase yields without compromising quality. A crop thinning trial was conducted in 2010 and 2011 to address these concerns and to better understand the role of vine balance on fruit composition. Crop levels were moderately (35% crop removed) or severely (65% crop removed) thinned at pre-bloom, fruit set, lag phase, or véraison and compared to full crop treatments. In both years, crop thinning reduced yields but had no effect on berry weight or cluster size. In 2010, poor fruit set reduced overall yields, and thinning treatments resulted in very few differences in vine growth, cluster architecture or fruit composition, including total soluble solids (TSS), pH, titratable acidity (TA), yeast assimilable nitrogen (YAN), anthocyanins, phenolics and tannins. In 2011, yields were much higher due to high fruit set and larger cluster size. No differences were found in vine growth (leaf areas or pruning weights) or fruit YAN, but thinned vines had higher TSS and pH and lower TA than full crop vines at harvest. Fruit thinned at lag phase and véraison had higher TSS and lower TA than fruit thinned pre-bloom. Intensity of thinning had a stronger influence on anthocyanin and tannin concentration than timing, while phenolics were not impacted by either factor. Ravaz index values (fruit yield/pruning weight) below 2.25 and leaf area to yield ratios of 2.25 to 3.25 m²/kg improved fruit composition in 2011 as did later season thinning, though data from the remaining years of this study will provide more insight into appropriate crop load metrics for cool climate Pinot Noir. A second study was implemented in 2011 to determine the impact of crop thinning in vines with different levels of vegetative vigor caused by three vineyard floor management techniques: permanent grass (Festuca rubra spp. rubra) cover (grass), alternating grass cover and tillage (grass & tilled), and tillage of every alleyway (tilled). Crop was thinned at the BB stage of berry development (EL stage 73) to one cluster per shoot (half crop) or not thinned (full crop); all cluster wings were removed at the time of thinning. Tillage treatments had been in place four years prior to the start of the study and competition for nitrogen in grass caused reduced early season vine growth, leaf chlorophyll and canopy size at both bloom and véraison while crop thinning increased canopy size at véraison. Yields were altered by tillage and crop thinning treatments, as grass had fewer clusters per shoot and berries per cluster, and crop thinning reduced yields to 64.7% of full crop across all tillage treatments. At harvest, grass had the lowest TA while TSS and pH were not affected by tillage. Crop thinning increased TSS but did not impact pH or TA. Anthocyanins were affected by both tillage and thinning and were found to be related to vine yield, YAN, leaf N, and leaf area index. Tannins were highest in grass but were not affected by crop thinning, and phenolics were not changed by either factor. Few interactions between tillage and crop thinning were found, but as variables such as yield per vine were impacted by both treatment factors, monitoring long term effects of crop / Graduation date: 2012

Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: The financial decision-making environment within which wine-grape producers function is challenging because of the complex interrelationships between yield, product price and input requirements. The complexity of farm systems is increased because production and financial decisions are necessarily made under uncertainty. Various issues influence the resilience of the wine industry. The goal of this study is to determine the financial implications of irrigation, integrated with canopy management practices on red wine cultivars in the Robertson area. Canopy management and irrigation cost play an important role within the multi-faceted farm system regarding yield, quality and input cost. This necessitates that research be carried out within the context of a systems approach. In this manner the interdependence among the various components of the farm system, and the associated synergies can be captured. Farm management, as a field of research, is dependent on other disciplines that present an alternative perspective to the research problem. Viticulture trials specifically focused on the impact of various irrigation and canopy management activities is being done on Wansbek farm. Nine treatments were tested at various combinations of soil water depletion levels and canopy management strategies. The farm is situated in Agterkliphoogte, an area in the Robertson valley. A multi-disciplinary group discussion was held to firstly obtain insight in the complex working of a farm. Secondly the group discussion was used to gain insight into the application of the Wansbek trial data and the setting of guidelines as to its application to determine the expected farm level financial implications of the treatments. Dealing with complexity necessitates insight form various areas of expertise, which is achieved time efficiently within expert group discussions. A quantitative method is required to reflect the interrelatedness and dynamics of a whole farm system in a user-friendly manner. Multi-period budget models present the ability to accommodate the complexity associated with a farm through a sequence of mathematical and accounting equations. The physical/biological interrelations and structure of the farm can be modelled while the financial performance of various irrigation and canopy management strategies can be determined. Farm-level profitability is especially sensitive to yield and price of farm products. The treatments that showed the highest expected profitability, return relatively high yields and prices at relatively low production costs. The sprawling canopy management treatment at c. 60% and c. 30% plant available water depletion levels returned the highest and second highest profitability at both gross margin per hectare and whole farm level. Scenarios were incorporated to illustrate the expected impact of key variables and the capability of the model. Key factors associated with the success of specific treatments could be identified. Results showed throughout that the balance between yield, price and input cost are the determining factor to profitability, rather than a focus on any particular one of these factors. / AFRIKAANSE OPSOMMING: Die finansiële besluitnemingsomgewing waarbinne wyndruifprodusente funksioneer, is uitdagend weens die komplekse verwantskappe tussen oesopbrengs en -kwaliteit en gepaardgaande insetbehoeftes. Die kompleksiteit van die boerderystelsels word verhoog deurdat produksie- en finansiële besluite noodwendig op grond van onvolmaakte inligting geneem word. Verskeie kwessies beïnvloed die voortbestaan van die wynbedryf. Die doel van hierdie studie is om die finansiële implikasies te bepaal van besproeiing, geïntegreer met lowerbestuur, vir rooi wyndruifverbouing in die Robertson-wynvallei. Lowerbestuur- en besproeiingkoste speel ʼn belangrike rol binne die multifasettigheid van ʼn boerderystelsel ten opsigte van opbrengs, kwaliteit en produksiekoste. Dit vereis dat die navorsing binne die konteks van die stelselsbenadering aangespreek word. Sodoende word die interafhanklikheid tussen die onderskeie boerderystelselkomponente, gekoppel aan die sinergistiese effek wat daarmee gepaardgaan, in ag geneem. Boerderybestuur as navorsingsveld, is gevolglik afhanklik van ander vakdissiplines wat ‘n alternatiewe perspektief verleen aan die navorsingsprobleem. Wingerdbouproewe wat spesifiek fokus op die impak van verskillende besproeiing- en lowerbestuursaksies word uitgevoer op die Wansbek-plaas. Die plaas is geleë te Agterkliphoogte, ʼn area in die Robertson-vallei. Nege behandelings is getoets teen verskillende kombinasies van plant beskikbare water (PBW)-onttrekkingspeile en lowerbestuurstrategieë. ʼn Groepsbespreking met multidissiplinêre deskundiges is gehou om eerstens, insig in die kompleksiteit van die werking van ʼn plaas te verkry. Tweedens, is die groep van multidissiplinêre deskundiges gebruik om insig te verwerf aangaande die hantering van die Wansbek-proefdata. Die groep het riglyne daargestel om die proefdata prakties aan te wend sodat die verwagte finansiële implikasies op plaasvlak geëvalueer kan word. Die hantering van kompleksiteit vereis insig vanuit verskeie gebiede van kundigheid wat tydsdoeltreffend binne ʼn groepsbespreking van multidissiplinêre deskundiges geakkommodeer kan word. ʼn Kwantitatiewe tegniek is nodig om die wisselwerking en dinamika van ʼn geheelboerderystelsel op ʼn gebruikersvriendelike en toepaslike manier te weerspieël. Multiperiode-begrotingsmodelle gee die vermoë om die kompleksiteit, wat met ʼn tipiese plaas geassosieer word, te akkommodeer deur die toepassing van basiese wiskundige en rekeningkundige beginsels. Die fisies-biologiese wisselwerking en struktuur van die plaas kan sodoende gemodelleer word, terwyl die finansiële prestasie van die kombinasies van verskillende besproeiing- en lowerbestuurstrategieë bepaal kan word. Die plaasvlakwinsgewendheid is veral sensitief vir die opbrengs en prys van produkte gelewer. Die behandelings wat die beste verwagte winsgewendheid getoon het, produseer teen ʼn relatiewe hoë produksie en prys en ’n relatiewe lae produksiekoste. Die oophanglowerbestuurbehandeling teen c. 60% en c. 30% plant beskikbare water-onttrekkingspeile is die mees en tweede mees winsgewende strategieë op per hektaar bruto marge en geheelplaasvlak. Die gebruik van scenario’s is geïnkorporeer om die impak van sleutelveranderlikes uit te wys en die vermoë van die model te illustreer. Sleutelfaktore tot die sukses wat aan sekere strategieë verbind word, kan sodoende uitgewys word. Deurgaans wys die resultate dat die balans tussen opbrengs, prys en produksiekoste belangriker is as die fokus op enige enkele een van die faktore.

Thesis (MScAgric (Viticulture and Oenology))--University of Stellenbosch, 2007. / The South African and international table grape industries are growing rapidly, which necessitates the production of high quality export fruit at competitive production costs. For this reason, alternative irrigation methods are required to utilise water optimally while still attaining good quality table grapes. An increase in agricultural productivity may be dependent on either the availability of more water for irrigation or an increase in the efficiency of water use. The first aim of this study was to evaluate the effectiveness of the Partial Rootzone Drying (PRD) irrigation strategy in Crimson Seedless and Dauphine table grape production. This irrigation system is based on the drying of half of the vine roots, thereby allowing the plant to produce hormones like abscisic acid (ABA) in reaction to water stress. The hormone production in turn results in stomatal closure and the reduction of water loss via transpiration. The drying cycle is then repeated after 10 to 15 days on the other side of the vine, irrigating the previously dried roots. PRD will encourage a consistent production of the stress hormone abscisic acid (ABA), without actual water stress. This strategy reduces the amount of water used for irrigation, without an accompanying loss in fruit yield, as compared to conventional techniques. In this study, conventionally treated vines were irrigated according to historical block data and PRD-treated vines were irrigated at the same times. The second aim of this study was to monitor the efficacy of a foliar nutrient, Croplife. This foliar nutrient allegedly improves the uptake of foliar applied nutrients, assists with transport of all minerals through the leaves and enables the plant to attain higher pest and disease resistance thresholds. Conventionally treated vines that did not receive foliar nutrient treatment were compared to vines that received foliar nutrients as prescribed by the manufacturer. Vine cultivars Crimson Seedless and Dauphine, were grown under open hydroponic principles with drip and drip irrigation respectively in this experiment. For the hydroponic vines (Crimson Seedless), all vines were situated in the same row and 72 vines were divided into mini-plots of three vines. Treatments were then assigned to an equal number of plots at random. The same procedure was followed for the drip irrigated vines (Dauphine) but the vines were situated in two rows of equal length. Treatment effects were followed from budburst until harvest, where after post-harvest analyses were conducted. The first aim, namely to show that PRD is an effective irrigation strategy for table grape production in Crimson Seedless and Dauphine cultivars , has shown that vines did not exhibit signs of stress even though they received only half the conventional amount of water. This study was conducted over only one growth season and therefore no definite conclusions could be drawn about the long term effectiveness of PRD on table grapes. It did, however, confirm numerous results obtained from different studies on the use of PRD in wine grape production. The results obtained in the second part of the study were inconclusive and could not show that Croplife is effective in improving the uptake and transport of applied foliar nutrients. Because Crimson Seedless is cultivated under open hydroponic principles, nutrients can be absorbed by the roots via the soil and micronutrients are also available from chemical sprays during the season. There was no evidence to indicate that the use of Croplife increased nutrient absorption and transport, neither did it supplement or detract form the observed effect of PRD. Despite the limitations experienced during this study, it has shown that the use of PRD for table grape production may be a useful tool for improving water utilisation efficiency in future. The strategy will have to be developed systematically through experimentation to fully unlock the potential of the PRD management system for table grape production. This study provides a good starting point for future research required to elucidate numerous aspects of the PRD system and has clearly shown that established vineyards can be switched to a PRD system without a loss in table grape quality. It is envisaged that the advantages of this system could have a positive effect on the production of high quality fruit for the international market.

Thesis (MscAgric (Viticulture and Oenology))--University of Stellenbosch, 2006. / Under certain South African conditions, Redglobe develops a colour that is too dark and thus unacceptable for the Far Eastern markets. These markets require a pink colour instead of a dark red colour. The cultivation of grapes with an acceptable colour involves amongst other, canopy management practices. This generally includes the removal of leaves and/or lateral shoots. Hereby, the leaf area and the microclimatic conditions in the canopy are altered. The aim of this study was to test the usefulness of leaf and lateral shoot removal at different defoliation times after anthesis in order to obtain a pink coloured Redglobe crop. Other quality aspects, namely total soluble solids (TSS), total titratable acidity (TTA), berry mass and total yield, were also evaluated. A canopy management trial was conducted on six year old Redglobe vines with moderate vigour. The treatment design was a 2 x 3 x 4 factorial and involved two leaf removal (L) levels (L0 = 0% leaf removal; L33 = 33% leaf removal) in combination with three lateral shoot removal (LS) levels (LS0 = 0 % lateral shoot removal; LS50 = 50% lateral shoot removal; LS100 = 100% lateral shoot removal). Four defoliation times (DT) were selected: 36 (pea berry size), 69 (véraison), 76 (one week after véraison) and 83 (two weeks after véraison) days after anthesis (DAA). A total of 24 treatment combinations, replicated in four blocks, were applied. Generally, treatment combinations involving 33% leaf removal lowered the main shoot leaf area. Likewise, the lateral shoot leaf area was decreased by increasing levels of lateral shoot removal at any defoliation time. As expected, 33% leaf removal applied in combination with any level of lateral shoot removal, always resulted in a lower total vine leaf area compared to where 0% leaf removal was part of the treatment combination. Compensation reactions occurred and in this regard the main shoot leaf size increased due to 33% leaf removal applied at 1 week after véraison and 2 weeks after véraison. Treatment combinations involving lateral shoot removal increased the ratio of main shoot leaf area to the total leaf area. On the other hand, the main shoot leaf area percentage was lowered by the application of 33% leaf removal at 2 weeks after véraison compared to no leaf removal at the same defoliation time. It can therefore be assumed that the contribution of lateral shoot leaves to grape composition might have increased in cases where the main shoot leaf area was lowered at a later stage (e.g. 2 weeks after véraison). The bunches were visually evaluated and divided into classes from dark (class one) to light (class nine). This visual bunch evaluation showed that the mean bunch colour was in class three (lighter than class two) due to the defoliation time. The lateral shoot removal x leaf removal interaction resulted in a mean bunch colour that was in classes 2 and 3. However, within these classes, there was a tendency that bunch colour decreased for defoliation times later than pea berry size. The lateral shoot removal x leaf removal interactions showed that bunch colour was darker when the treatment combinations involved 0% leaf removal. The percentage of bunches with the desired colour was increased by application of the treatments at véraison, compared to the other defoliation times, and also with 50% lateral shoot removal and 100% lateral shoot removal compared to 0% lateral shoot removal. Biochemical analyses confirmed that increased levels of lateral shoot removal generally lowered the anthocyanin concentration regardless of defoliation time. A similar effect on TSS was observed, i.e. from véraison onwards, the application of 50% lateral shoot removal and 100% lateral shoot removal tended to lower TSS. The effect of these levels of lateral shoot removal at véraison was significant. The role of the lateral shoots in colour development and sugar accumulation is therefore emphasized. Furthermore, the special role that lateral shoots also play in berry development is illustrated in that berry mass tended to decrease when 100% lateral shoot removal in combination with 33% leaf removal and 100% lateral shoot removal in combination with 0% leaf removal were applied at véraison. This, together with the positive relationship obtained between grape colour and the lateral shoot leaf area:fruit mass ratio, accentuates the role of active leaf area during the ripening period. The possible effect of the microclimatic light environment on colour must also be considered. However, although the light intensity increased with increased levels of LS, the colour that was obtained was probably not associated with the differences in light intensity. It was found that it is possible to manipulate the colour of Redglobe grapes with defoliation treatments. However, the treatments that have a decreasing effect on grape colour also affected other quality parameters like TSS and berry size negatively. Although, it is possible to reduce the colour of Redglobe through the application of leaf and lateral shoot removal at different defoliation times, the question arises whether the treatment combinations used in this study are worthwhile to pursue because the mean bunch colour that was obtained was still too dark. However, it was possible to increase the percentage of bunches with the desired colour. Therefore, if such treatments are applied, it must be approached cautiously, keeping in mind that assimilate supply has to be sustained throughout the ripening period.

Thesis (MScAgric (Viticulture and Oenology))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: Cabernet Sauvignon is the most planted red cultivar in South Africa and the second most planted red cultivar in the Olifants River region. The cultivar is prone to vigorous growth with low yields. Excessive irrigation could accentuate these cultivar characteristics. Considering the foregoing, the aim of the study was to describe how Cabernet Sauvignon will react to climate, soil type (texture) and irrigation within the Lower Olifants River wine region to enable growers to make the right decisions regarding long term as well as short term cultivation practices. This study is part of a project carried out by the ARC Infruitec-Nietvoorbij at Stellenbosch to determine the effects of soil type and atmospheric conditions on yield and wine quality of Cabernet Sauvignon in different grape growing regions of South Africa. Similar studies are being carried out in the Orange River, Stellenbosch and Swartland regions of South Africa. The Lower Olifants River region could be divided into three climatic regions. Furthermore, two climatic regions is evident regarding the formation of grape wine colour and aromas. Proximity to the Atlantic Ocean would play an important role in a cultivar establishment policy. The variation in stem water potential (ΨS) could be related to soil water status expressed in terms of matric potential (ΨM). In the case of sandy soils, ΨS decreased substantially more as the ΨM decreased compared to the sandy loam soils. The reason could be that the unsaturated hydraulic conductivity in sandy soils decreased more rapidly as the ΨM decreased compared to the heavier soils. Thus could explain why the grapevines in the sandy soils experienced more water stress than the ones in the sandy loam soils at a given ΨM. Climate had a strong influence on grapevine water status with grapevines nearer to the ocean experiencing less water stress compared to the ones further inland. This was especially true for grapevines in the sandy soils. Vegetative growth and yield of grapevines in the sandy soils were more sensitive to water deficits compared to the ones in the sandy loam soils. For deficit irrigated grapevines in the sandy soils, vegetative growth and yield decreased by ca. 30% when ca. 55% less water was applied from flowering to harvest. Yield reduction were ca. 15% with no or very little influence on vegetative growth with ca. 80% reduction in water applied from flowering to harvest for grapevines in the sandy loam soils. The influence of soil texture on wine quality and style were evident under intensive irrigation as well as over different climatic regions. Overall sensorial potential wine quality of grapevines in sandy soils tended to be higher compared to the ones in the sandy loam soils. Deficit irrigation tended to increase wine colour intensity, irrespective of soil texture. Furthermore, deficit irrigation in sandy loam soils tended to increase wine fullness and the berry characteristics of the wine. Berry characteristics of wines from the sandy soils tended to be higher compared to the ones from the sandy loam soils. Too severe water deficits in sandy soils could be detrimental to wine quality. Climate tended to have an influence on wine style of grapevines in the sandy soils with wines produced further away from the ocean tended to have higher berry characteristics. Irrigation management could be a powerful tool to manipulate the grapevine in sandy soils. For grapevines the sandy loam soils in addition to regulated deficit irrigation, additional canopy management practices could be needed to improve wine quality. / AFRIKAANSE OPSOMMING: Cabernet Sauvignon is die mees aangeplante rooidruif kultivar in die Suid-Afrikaanse wynbedryf. In die Olifantsriver streek is dit naas Shiraz, die tweede mees aangeplante rooidruif kultivar. Cabernet Sauvignon is bekend as ‘n groeikragtige skaamdraer. Indien oorbesproei word, kan hierdie potensiële nadelige eienskappe nog meer na vore tree. Die doel van die studie is om die invloed van die klimaat, grond en besproeiing op Cabernet Sauvignon se vegetatiewe groei, produksie en wyngehalte in die Benede Olifantsrivier streek te bepaal. Hierdie inligting kan produsente help om ingeligte kortsowel as langtermyn besluite te maak rakende die verbouing van Cabernet Sauvignon. Hierdie studie vorm deel van ‘n breër studie in die Suid-Afrikaanse wynbedryf, gedryf deur die Landbou Navorsingsraad (LNR) Infruitec-Nietvoorbij, Stellenbosch om die invloed van atmosferiese toestande en grond op die produksie en wyngehalte van Cabernet Sauvignon te bepaal. Soortgelyke projekte word uitgevoer in die Oranjerivier, Stellenbosch en Swartland wynstreke. Die Benede Olifantsrivier streek kan verdeel word in drie klimaatstreke op grond van temperatuurdata. In terme van die ontwikkeling van druifkleur en aromas, kan die streek verdeel word in twee klimaatstreke. Die afstand vanaf die Atlantiese Oseaan kan ‘n belangrike rol speel in die ontwikkeling van ‘n kultivarriglynplan vir die streek. Grondwaterstatus, uitgedruk as die matrikspotensiaal (ΨM), kan aanleiding gee tot variasie in middag blaarwaterpotensiaal (ΨS) lesings. Die ΨS van die sand gronde verlaag vinniger soos die ΨM verlaag invergelyke met die sandleem gronde. Dit kan moontlik wees as gevolg van die verskil in die grond onversadigde hidroliese konduktiwiteit. Sand gronde se hidroliese konduktiwiteit verlaag vinniger soos die ΨM verlaag, invergelyke met sandleem gronde. Dit verklaar waarom wingerde in sand gronde by dieselfde ΨM, meer waterspanning ondervind as wingerde in sandleem gronde. Klimaat het ‘n invloed op die waterstatus van die wingerdstok. Wingerde nader aan die see het minder waterspanning ondervind invergelyke met wingerde wat verder in die binneland geleë is. Dit was veral die geval met wingerde in die sand gronde. Vegetatiewe groei en produksie van wingerde in die sand gronde is meer sensitief vir waterspanning as wingerde in die sandleem gronde. Tekortbesproeiing in die sand gronde het die groei asook produksie met ongeveer 30% verlaag deur ongeveer 55% minder water toe te dien vanaf blom tot oes. In teenstelling daarmee is die produksie van wingerde in die sandleem gronde met ongeveer 15% verlaag met geen tot baie min verlaging in die groeikrag. Ongeveer 80% minder water is toegedien vanaf blom tot oes. Grondtekstuur kan wyngehalte en -styl beïnvloed ten spyte van intensiewe besproeiing en klimaatsverskille. Sensoriese potensiële wyngehalte van wingerde in die sand gronde was beter invergelyke met dié van die sandleem gronde. Die wyne vanaf die sand gronde het ook geneig om oor meer bessie intensiteit te beskik as wyne vanaf die sandleem gronde. Tekortbesproeiing neig om die wynkleur intensiteit te verhoog, ongeag van grondtekstuur. Tekortbesproeiing in die sandleem gronde kan ook die volheid van die wyne verbeter, asook die bessie intensiteit van die wyn verhoog. Te hoë waterspanning in die sand gronde kan wyngehalte nadelig beïnvloed. Klimaat kan ook die wynstyl vanaf sand gronde beïnvloed met wyne verder vanaf die see wat oor meer bessie intensiteit beskik as wyne nader aan die see. Beheerde tekortbesproeiing kan as ‘n kragtige hulpmiddel gebruik word om wingerde in die sand gronde te manipuleer. Vir wingerde in die sandleem gronde, addisioneel tot beheerde tekortbesproeiing en normale loofbestuurspraktyke, kan ekstra loofbestuurspraktyke bv. die verwydering van sylootlote, dalk nodig wees om wyngehalte te verbeter.

Thesis (MComm)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Table grapes are the second-largest contributor to the perishable product export in South Africa. The table grape industry also experienced considerable growth in the past ten years. The industry contributes toward employment in South Africa. The South African table grape industry experiences quality-related problems with exporting table grapes to the European market. Examples of quality related problems can range from chemical damage, chilling injury/freezing damage, heavy bruising and decay. A great amount of table grapes is basically wasted. The postharvest loss of table grapes during transportation can range from 1%-25% per day depending on the degree of temperature fluctuation. Therefore, it is important to minimize waste and increase the export volumes in order to utilise the potential profit possibilities. Based on data analysis for this case, results indicated that packaging is preventing cool air from flowing through the pallet during transportation and preventing the table grapes to cool evenly. The fluctuation in temperature contributes to the qualityrelated problems of these table grapes. The primary research goal is to identify packaging-related problems and propose possible solutions to improve the packaging-related conditions in which table grapes arrive at the destination. This study therefore investigated and evaluated the performance of the current packaging system of table grapes within a South African context for exporting to Europe for a specific case. Further analyses of the data received from Dole South Africa, a fruit marketing and distribution company, revealed that the following two types of packaging showed serious quality-related problems: 1) A04I: The 4.5kg box with the grapes in plastic bags. 2) A05E: The 5kg box with 500g punnets (10 x 500g punnets). A questionnaire combining with the Packaging Portfolio Evaluation Model and the Packaging Scorecard was developed and used to evaluate the two identified packaging systems in the following stages: Stage 1: Development of a new questionnaire by combining the Packaging Portfolio Evaluation Model and the Packaging Scorecard. Stage 2: Survey with the questionnaire developed in Stage 1. The identified types of packaging were evaluated with a new questionnaire with specific criteria. Members of the table grape supply chain from the farmer in South Africa to consumer in Sweden were used during the evaluation process. Descriptive statistics were calculated for each criteria or question in order to describe the performance and importance of the different packaging criteria. Data were also analysed with the use of box plots. The box plots and data visualisation methods were used to make conclusions and recommendations regarding the different categories of each type of packaging. It was clear that the major problem areas of both packaging systems involved were related to the environmental aspect of the packaging. The marketing and the logistics of the plastic bag also underperformed. However, individual criteria regarding the other business areas can also be improved. Possible solutions to these problem areas are also suggested in this thesis. The possible solutions include the Tali Grape Basket, Perforated Plastic Liners, New Generation Pack (NGP), Vinguard TM , Easypunnet and the Sulphur Dioxide Liner Bag. / AFRIKAANSE OPSOMMING: Tafeldruiwe is die tweede grootste bydraende faktor tot bederfbare produkuitvoere in Suid-Afrika. Die tafeldruifindustrie het ook aansienlike groei die afgelope tien jaar beleef. Die industrie dra tot werkskepping in Suid-Afrika by. Die Suid-Afrikaanse tafeldruifindustrie ervaar kwaliteitsverwante probleme met die uitvoer van tafeldruiwe na die Europese mark. Voorbeelde van hierdie kwaliteitsverwante probleme kan wissel van chemiese skade, koueskade / vries skade, swaar kneusing en bederf. ‘n Groot hoeveelheid tafeldruiwe word vermors. Die oes verlies van tafeldruiwe tydens vervoer kan wissel van 1% -25% per dag, afhangende van die mate van temperatuur verandering. Daarom is dit belangrik om vermorsing te beperk en uitvoerhoeveelhede te verhoog om sodoende potensiële winsmoontlikhede te benut. Volgens data-analise blyk dit dat huidige verpakking tans verhoed dat koel lug tydens die vervoer van die produk deur die palet vloei, en dit veroorsaak dat die tafeldruiwe nie eweredig afkoel nie. Die wisseling in temperatuur dra grootliks tot die kwaliteitsverwante probleme van die tafeldruiwe by. Die primêre navorsingsdoelwit is om die verpakkingsverwante probleme te identifiseer en moontlike oplossings voor te stel om sodoende die toestand te verbeter waarin tafeldruiwe by die eindbestemming aankom. Daarom ondersoek en evalueer hierdie studie die prestasie van die huidige verpakkingsisteem van tafeldruiwe binne ʼn Suid-Afrikaanse konteks vir uitvoere na Europa; met betrekking tot ʼn spesifieke situasie. Verdere analise van data soos ontvang vanaf Dole Suid-Afrika, ‘n vrugtebemarkingsen verspreidingsmaatskappy, het getoon dat ernstige kwaliteitsverwante probleme veral by die volgende twee tipes verpakkingsisteme voorkom: 1) A04I: Die 4.5kg karton met druiwe in plastieksakkies. 2) A05E: Die 5kg karton met 500g bakkies (10 x 500g bakkies). ʼn Vraelys, gebaseer op die kombinasie van die Verpakkingportefeulje Evalueringsmodel model en die Verpakkingstelkaart, is ontwikkel en gebruik om die bogenoemde verpakkingsisteme te evalueer en wel in die volgende fases: Fase 1: Ontwikkeling van ʼn gekombineerde Verpakkingsportefeulje Evalueringsmodel en die Verpakkingstelkaart tot ʼn nuwe vraelys. Fase 2: Opname met die vraelys soos ontwikkel in Fase 1. Die twee geïdentifiseerde tipes verpakking is geëvalueer met die nuwe vraelys met spesifieke kriteria. Die lede van die tafeldruiwe voorsieningsketting van die boer in Suid-Afrika tot die verbruiker in Swede is gebruik tydens die evaluasieproses. Beskrywende statistiek vir elke kriteria of vraag was bereken sodat die prestasie en belangrikheid van die verskillende verpakkingskriteria beskryf kan word. Data was ook beskryf met behulp van ‘n houer-en-puntstipping. Data visualiseringmetodes en die houer-en-puntstippings was gebruik om gevolgtrekkings en aanbevelings rakende die verskillende kategorieë van die tipes verpakking te maak. Dit was duidelik dat die omgewingsaspek van beide tipes verpakking ‘n groot probleem was. Die bemarking en logistiek van die plastieksakkie het ook onderpresteer. Individuele kriteria van ander besigheidsareas kan egter ook verbeter word. Moontlike oplossings vir hierdie probleem-areas word ook in hierdie tesis aangedui. Die moontlike oplossings sluit die “Tali Grape Basket”, “Perforated Plastic Liners”, “New Generation Pack (NGP)”, “Vinguard TM ”, “Easypunnet” en die “Sulphur Dioxide Liner Bag” in

Thesis (MSc)--University of Stellenbosch, 2000. / ENGLISH ABSTRACT: Agrobacterium tumefaciens-mediated transformation technology has been used in a variety of applications throughout the fields of cellular and molecular plant biology as well as plant physiology. Research is conducted in order to extend this application range and overcome some of the intrinsic limitations of the Agrobacterium transformation system. Predominantly, these limitations can be attributed to the host range specificity of A. tumefaciens, as well as adverse effects induced on explant tissue by active plant defence mechanisms, triggered by the plant-pathogen-interaction. Typically, this active defence mechanism culminates in the hypersensitive response (HR), characterised by localised cell death and necrosis. Not all Agrobacterium species, however, share the same host range and some have evolved the ability to infect plant species not normally considered hosts of A. tumefaciens. This host range specificity can be exploited to extend the application of existing Agrobacterium transformation systems. In an attempt to establish an efficient transformation system for Vitis vinifera which, has proven very difficult to transform with A. tumefaciens, indigenous A. vitis strains have been evaluated as possible host-specific transformation agents. Strains of Agrobacterium vitis should be suitable for this type of endeavour, since they have evolved several unique characteristics directly linked to the infection of their hosts. These include the ability to utilise, tartrate, a host abundant carbon source, as well as the production of an acid polygalacturonase that could play a role during the infection process. The proposition that the evolution of A. vitis is a fairly recent event is also confirmed by the relatively little divergence observed between A. tumefaciens and A. vitis. In this study, a selection of A. vitis strains were evaluated in screenings designed to accentuate desirable traits in strains such as good infectivity of grapevine material (presumably an indicator of an efficient mechanism of gene transfer to be exploited in an engineered transformation system) as well as a favourable reaction (causing no necrosis) on grapevine somatic embryos. Two strains produced large tumours on grapevine cuttings and caused little necrosis on the somatic embryos. Significant variation in infectivity as well as callus necrosis was observed between the strains as well as in a genotype-specific manner on the host material. This genotypic-specific effect of either host or pathogen could be an indication of the degree of specialisation developed by plant pathogens to infect specific hosts. On the basis of these results, it was possible to select an A. vitis strain for further biochemical and genetic characterisation. Simple biochemical analysis classified the strain as an octopine strain. DNA-DNA hybridisation techniques combined with a plasmid walking technique resulted in the partial characterisation of the T-DNA of the selected A. vitis strain. A partial restriction enzyme map of the T-DNA was constructed and the T-DNA and flanking areas were cloned. Significant differences, most notably, the absence of a TB-area as well as the absence of the agrocinopine (aes) gene from the 5' area of the T-DNA, were observed. Partial sequencing data indicated the presence of at least four conserved T-DNA genes located on the TA-DNA, as well as the presence of three bacterial insertion (IS-)elements flanking the region. Two of these IS elements, both related to the IS 110 family of IS elements have not yet been reported in A. vitis. In fact, these two elements seem to be the 5' and 3' ends of a disrupted element and could therefore have played an evolutionary role in the development of this strain. This study provides fundamental background for the development of a more efficient transformation system specific for grapevine, exploiting same of-the unique characteristics of one of its pathogens, A. vitis. / AFRIKAANSE OPSOMMING: Agrobacterium tumefaciens-gebaseerde transformasiesisteme word in "n wye reeks van toepassings in die velde van sellulêre- en molekulêre plantbiologie asook plantfisiologie aangewend. Navorsing word voortdurend onderneem om die inherente beperkinge van die Agrobacterium-transformasiesisteem te oorkom en sodoende die toepassingsveld van die sisteem verder te verbreed. Die beperkinge tipies aan dié sisteem kan hoofsaaklik toegeskryf word aan die gasheerspesifisteit van A. tumeteciens, asook die negatiewe reaksies op eksplantmateriaal wat deur die plant se aktiewe verdedigingsmeganisme, soos ontlok deur die plant-patogeen interaksie, veroorsaak word. Hierdie aktiewe verdedigingsmeganisme lei gewoonlik tot In hipersensitiewe respons (HR) in die plant, wat deur gelokaliseerde selafsterwing en nekrose gekenmerk word. Alle Agrobacterium-spesies het egter nie almal dieselfde gasheerreeks nie en sommige rasse het as gevolg van evolusionêre ontwikkelings die vermoë verkry om plantspesies wat normaalweg buite die gasheerreeks van A. tumefaciens val, te infekteer. Hierdie tipe gasheerspesifisiteit kan uitgebuit word om die toepassingsmoontlikhede van bestaande Agrobacterium-transformasiesisteme te verbreed. In In poging om In effektiewe transformasiesisteem vir Vitis vinifera, In moeilik transformeerbare gewas, te ontwikkel, is inheemse rasse van Agrobacterium vitis ondersoek as moontlike gasheerspesifieke transformasie-agente. Rasse van A. vitis behoort uiters geskik te wees vir so "n toepassing, aangesien hulle verskeie unieke eienskappe, wat direk aan die infeksie van die gasheer gekoppel is, vertoon. Van hierdie eienskappe is onder meer die vermoë om tartraat, In koolstofbron volop in druifplante, te benut. A. vitis produseer verder ook In suur poligalaktorunase wat vermoedelik In rol in die infeksieproses speel. Die voorstel dat die evolusionêre ontwikkeling van A. vitis In redelike onlangse gebeurtenis is, word onderskryf deur die betreklike homogenisiteit met A. tumefaciens. In hierdie studie is "n groep A. vitis-rasse met behulp van siftingsprosedures wat daarop gemik is om gesogte eienskappe in rasse uit te wys, beoordeel. Die vermoë om druifplantmateriaal te infekteer (wat vermoedelik "n aanwyser van "n effektiewe meganisme van geenoordraging is wat in "n gemanipuleerde transformasiesisteem benut kan word), sowel as 'n gunstige reaksie (d.w.s geen nekrose) op druifplant somatiese embrio's is van die gesogte eienskappe waarvoor gesoek word. Twee rasse het groot tumors op druifplant-stingelsegmente veroorsaak terwyl hulle bykans geen weefselskade op somatiese embrio's geïnduseer het nie. Betekenisvolle verskille in infektiwiteit en in kallusnekrose is tussen die rasse sowel as in 'n genotipe-spesifieke-verhouding waargeneem. Hierdie genotipe-spesifieke effek, kenmerkend van óf die gasheer óf die patogeen, kan aanduidend wees van die vlak van spesialisasie wat heers by die infeksie van spesifieke gashere. Na aanleiding van bogenoemde resultate was dit moontlik om 'n A. vitis-ras te selekteer wat verder aan biochemiese en genetiese analises onderwerp kon word. Eenvoudige biochemiese analises het dit moontlik gemaak om die ras as oktopien te klassifiseer. DNA-DNA hibridisasietegnieke gekombineerd met 'n unieke plasmiedwandeltegniek het gelei tot die gedeeltelike karakterisering van die geselekteerde A. vitisras. In Gedeeltelike restriksie-ensiem (RE) kaart van die T-DNA kon gevolglik opgestel word. Die T-DNA en die aangrensende gedeeltes is boonop gekloneer. Betekenisvolle verskille, spesifiek die afwesigheid van In TB area, sowel as die afwesigheid van die agrosinopien-sintasegeen (acs) aan die 51-kant van die T-DNA, is waargeneem. Gedeeltelike basispaaropeenvolgingsdata het egter die teenwoordigheid van minstens vier gekonserveerde T-DNA-gene, asook die teenwoordigheid van drie bakteriese invoegingselemente (IS) aan weerskante van die area, geïdentifiseer. Twee van hierdie elemente, wat beide homologie vertoon met die IS110 familie van IS elemente, is nog nie vantevore in A. vitis aangetref nie. Dit wil boonop blyk of dié twee elemente die 51 - en 31 - areas van In onderbroke element vorm, wat dus In moontlike aanduiding is van hul potensiële rol in die evolusionêre ontwikkeling van die ras. Hierdie studie verskaf basiese inligting wat daartoe kan lei dat 'n doeltreffender transformasiesisteem spesifiek vir druifplante ontwikkel word deur van die unieke kenmerke van een van sy patogene, A. vitis, uit te buit.

Thesis (MScAgric)--University of Stellenbosch, 2000. / ENGLISH ABSTRACT: Petri grapevme decline, also known as black goo, slow die-back and Phaeoacremonium grapevine decline, causes significant losses of young vines worldwide. Species of Phaeoacremonium, Phaeomoniella chlamydospora and related genera are associated with this grapevine disease. This study investigates the Phaeoacremonium-complex and Phaeomoniella chlamydospora, focussing on the species isolated from grapevines. Fungicide sensitivity of Pa. chlamydospora and the possibility of employing molecular techniques for the detection of Pa. chlamydospora in grapevines were also investigated. In an overview of the literature on Petri grapevine decline the disease history and the relatedness of Petri grapevine decline to esca is discussed. Petri grapvine decline occurs in propagation material or young vines. Infected material can appear asymptomatic and therefore the possibilities of molecular techniques for identification were also investigated in the literature. In South Africa Pa. chlamydospora is the dominant organism causing Petri grapevine decline and therefore different fungicides were evaluated to control this fungus. Six isolates of Pa. chlamydospora, from Stellenbosch, Wellington, Somerset West and Malmesbury of Western Cape province, South Africa, were screened against twelve fungicides testing their effect on mycelial inhibition in vitro. These fungicides included benomyl, chlorothalonil, fenarimol, fosetyl-Al, iprodione, kresoxim-methyl, mancozeb, metalaxyl, prochloraz manganese chloride, quintozene, tebuconazole and thiram. Results provided the base-line sensitivity of South African isolates of Pa. chlamydospora. Benomyl, fenarimol, kresoxim-methyl, prochloraz manganese chloride and tebuconazole were the most effective (with EC50 values ranging from 0.01 to 0.05 ug/ml) for inhibiting mycelial growth of Pa. chlamydospora in vitro. This in vitro test gave a good indication of which fungicides could be selected for further studies in glasshouses and nurseries. The molecular phylogeny of Phaeoacremonium and Phaeomoniella isolates from grapevines of South Africa, or isolates obtained from the Centraalbureau voor Schimmelcultures (CBS) in the Netherland, were investigated. Sequence data were created from the rONA region and partial B-tubulin gene of 33 of these isolates using the PCR technique. This sequence data were analysed with PAUP* version 4.Ob2a. An analysis of the sequence data confirmed the genus Phaeomoniella to be distinct from Phaeoacremonium (Pm.) based on DNA phylogeny. Although morphologically similar, the species status of Pm. aleophi/um and Pm. angustius was confirmed with DNA phylogeny and cultural characteristics. Pm. aleophilum has an optimum growth rate at 30°C and the ability to grow at 35°C, where as Pm. angustius has an optimum growth rate at 25°C and cannot grow at 35°C_ Pm. viticola was shown to be synonymous with Pm. angustius, and a new species, Pm. mortoniae, was newly described from grapevine occurring in California. Futhermore, Pm. aleophilum was newly reported from South Africa and grapevine isolates thought to be Pm. inflatipes were all re-identified as Pm. aleophilum. These findings therefore also shed some doubt on the possible role of Pm. inflatipes in Petri grapevine decline. It was confirmed that Pa. chlamydospora, Pm. aleophilum and Pm. angustius are the species involved in Petri grapevine decline. Pm. mortoniae was isolated from grapevines, but its pathogenicity should still be confirmed and the role of Pm. injlatipes in Petri grapevine decline remains unclear. Pa. chlamydospora has been routinely isolated from symptomless propagation and nursery material. Because the disease can take years to develop, it is crucial that healthy propagation material is used at planting. Pa. chlamydospora is a slowgrowing fungus, and positive identification from symptomless grapevine tissue can take up to 4 wks. The possibility of employing molecular techniques for the detection of Pa. chlamydospora in apparently healthy grapevines was investigated. Speciesspecific primers (PCLI and PCL2) based on the regions ITSI and ITS2 were designed for Pa. chlamydospora. These primers were highly sensitive and amplification was achieved from genomic DNA of Pa. chlamydospora from as low as 16 pg. Phaeoacremonium spp., related genera and common fungal taxa from grapevines were tested with these primers, but positive amplification was achieved for Pa. chlamydospora only. The presence of Pa. chlamydospora in symptomless grapevine tissue culture plants was confirmed by PCR within 24 hours. These primers therefore allow rapid and accurate identification of Pa. c~lamydospora. Testing on a larger scale with nursery material should be conducted to determine the feasibility of using these species-specific primers in the grapevine industry. / AFRIKAANSE OPSOMMING: Petri-terugsterwing van jong wingerde, ook algemeen bekend as "black goo" en Phaeoacremonium-terugsterwing, veroorsaak wêreldwyd groot geldelike verliese in die wingerdbedryf. Spesies van Phaeoacremonium, Phaeomoniella chlamydospora en verwante genera word met hierdie wingerdsiekte geassosieer. In die tesis word In oorsig gegee van die geskiedenis van hierdie siekte, die verwantskap tussen Petriterugsterwing en esca, en moontlike maniere van siektebestuur. Swamme wat by die siektekompleks betrokke is, kan in simptoomlose plantweefsel voorkom en daarom is die moontlikhede van die gebruik van molekulêre tegnieke vir swamidentifikasie in oënskou geneem. In Suid-Afrika is Pa. chlamydospora die dominante swam wat met Petriterugsterwing geassosieerword, gevolglik is verskillende fungisiedes vir die chemiese beheer van Pa. chlamydospora geëvalueer. Ses isolate van Pa. chlamydospora, versamel vanaf verskillende areas in die Wes-Kaap provinsie, is in dié studie gebruik. Benomyl, chlorothalonil, fenarimol, fosetyl-Al, iprodione, kresoxim-methyl, mancozeb, metalaxyl, prochloraz manganese chloride, quintozene, tebuconazole en thiram se effek op miselium inhibisie van Pa. chlamydospora is in vitro geëvalueer. Benomyl, fenarimol, kresoxim-methyl, prochloraz manganese chloride en tebuconazole was die mees effektiewe middels. Die effektiewe konsentrasie waarby 50% van die miselium groei geïnhibeer is (EKso),was tussen 0.01 en 0.05 ug/ml vir die mees effektiewe groep middels. Benomyl, fenarimol, kresoxim-methyl, prochloraz manganese chloride en tebuconazole het in vitro goeie potensiaal getoon, en verder toetse moet in vivo uitgevoer word. 'n Molekulêre studie is van Phaeoacremonium en Phaeomoniella isolate; verkry uit Suid-Afrikaanse wingerde, of vanaf die "Centraalbureau voor Schimmelcultures" (CBS) van Nederland; gedoen. Deur van die PKR tegniek gebruik te maak, is die basispaaropeenvolgingsdata van 33 isolate, van die ITSl, 5.8S, ITS2 rDNA area en die gedeeltelike B-tubullen geen verkry. Gekombineerde molekulêre data het die teorie ondersteun dat Phaeomoniella (Herpotrichiellaceae) gedistansieerd is van Phaeoacremonium (Magnaporthaceae). Pm. aleophilum en Pm. angustius was morfologies moeilik onderskeibaar, maar kon op grond van molekulêre data en kulturele eienskappe onderskei word. Pm. aleophilum se optimum groeitemperatuur was by 30°C en die swam besit die vermoë om by 35°C te groei. Pm. angus/ius se optimum groeitemperatuur was by 25°C, maar het nie by 35°C gegroei nie. 'n Studie van molekulêre en kulturele eienskappe het getoon dat Pm. angus/ius en Pm. viticola sinoniem is. 'n Nuwe spesie, Pm. mortoniae, wat uit wingerde van Kalifornie geïsoleer is, is beskrywe. Verder is Pm. aleophilum die eerste keer in Suid-Afrikaanse wingerde aangetref en Pm. tnflatipes isolate, wat vanuit wingerde geïsoleer is, is almal met molekulêre data gewys om Pm. aleophilum te wees. Hierdie bevindinge trek die rol van Pm. inflatipes in Petri-terugsterwing van wingerde in twyfel. Phaeomoniella chlamydospora IS m voortplantingsmateriaal en kwekerystokkies opgespoor. Omdat dit jare kan duur voordat siektesimptome ontwikkel, is dit belangrik om vroegtydig te weet of jong stokkies met Pa. chlamydospora geïnfekteer is. Pa. chlamydospora groei baie stadig en positiewe identifikasie van simptoomlose infeksies duur tot vier weke. Die toepassing van molekulêre tegnieke vir die vinnige identifikasie van Pa. chlamydospora in wingerde is dus ondersoek. Spesie-spesifieke oligonukleotiedes (PCU en PCL2) is vir Pa. chlamydospora ontwerp. Hierdie oligonukleotiedes is uiters sensitief en genomiese DNA van Pa. chlamydospora is van so laag as 16 pg geamplifiseer. Phaeoacremonium spp., verwante genera en algemene swamme vanuit wingerdmateriaal is met die oligonukleotiedes getoets, maar positiewe amplifikasie was slegs met Pa. chlamydospora moontlik. Die teenwoordigheid van Pa. chlamydospora is binne 24 uur in asimptomatiese wingerd weefselkultuurplantjies bevestig. Hierdie oligonukleotiedes identifiseer Pa. chlamydospora vinnig en akkuraat en toetsing op 'n groter skaal moet vervolgens met kwekerymateriaal onderneem word.