There is little information published on red sorrel (Rumex acetosella L.), a perennial weed that is considered a serious problem in wild blueberry production. Hexazinone, a photosystem II inhibitor, has been used in wild blueberry fields for more than 30 years. Hexazinone efficacy on red sorrel has declined over time. Therefore, a two year study was conducted to examine hexazinone alternatives that can be sprayed in wild blueberry fields. Red sorrel ramets from mature blueberry fields were tested to determine whether long-term spraying of hexazinone selected for resistant red sorrel. The results show that hexazinone+rimsulfuron/nicosulfuron may be a alternative for hexazinone. Red sorrel from some blueberry fields is hexazinone-resistant and the resistance is caused by a Phe255 to Val mutation in the psbA gene.

Thesis (M.S.) in Ecology and Environmental Science--University of Maine, 2006. / Includes vita. Includes bibliographical references (leaves 91-95).

Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Profitability in the export driven South African blueberry industry is dependent on early spring harvests. The George region in the Western Cape accumulates too few chill-units to release buds of some southern highbush (SHB) blueberry cultivars from endodormancy. This causes problems like delayed budbreak and extended harvests. Growers of other temperate fruit crops are also affected by these problems and chemical rest breaking agents (RBAs) are applied in orchards in an attempt to overcome these. Application of the RBA hydrogen cyanamide (HC) occurs commonly in commercial pome and stone fruit orchards while thidiazuron (TDZ), another RBA is applied on a limited scale in apple orchards. The effect of RBA application on berry ripening, berry size and yield in SHB cultivars Bluecrisp, Emerald and Star was investigated for two seasons in an orchard near George, in order to determine to what extent harvest scheduling with RBAs is possible. Following Dormex® (HC, 520 g L-1) application during 2010, when a warm winter was experienced, the berry ripening of ‘Bluecrisp’ was accelerated. Dormex® application before reproductive bud scales opened, but after some chilling, resulted in acceptable yield and berry size without damage to reproductive buds. A 1% rate gave similar results as a 2% rate, but at a lower risk of reproductive bud damage. Lift® (TDZ, 3 g L-1) application reduced the number of days to 75% harvest in ‘Star’ during 2010. Lower yielding plants produced larger berries than those from higher yielding plants. Lift® application after reproductive buds scales have opened caused malformed and damaged flowers. Delaying the initiation of reproductive buds could delay spring reproductive budbreak until after new leaves had formed. In turn, this should induce a faster berry ripening rate in some SHB cultivars than would otherwise be the case following unseasonably warm winters. Reproductive bud initiation in SHB blueberries occurs under long (16 hours) nights with the mediation of phytochrome. It is possible in a controlled environment to suppress SHB blueberry reproductive bud initiation by night interruption (NI). The effect of NI on berry ripening, berry size and yield in ‘Emerald’ and ‘Snowchaser’ was investigated for two seasons, to determine what degree of harvest scheduling is possible with this technique. NI did not suppress reproductive bud development under these trial conditions, since both cultivars flowered and produced fruit. The effect on berry size and yield was cultivar specific. During 2011 NI decreased the number of berries harvested and total yield per plant in ‘Emerald’, and this decrease was linear the longer the NI lasted. / AFRIKAANSE OPSOMMING: Winsgewendheid in die uitvoer-gedrewe Suid-Afrikaanse bloubessie-bedryf is van vroeë lente oeste afhanklik. In die George-omgewing in die Wes-Kaap bou te min winterkoue op om die endodormansie van sommige ‘southern highbush’ (SHB) bloubessie kultivars natuurlik op te hef, wat probleme soos vertraagde bot en uitgerekte oestye veroorsaak. Produsente van ander gematigde vrugtesoorte, word ook deur hierdie probleme geraak en chemiese rusbreekmiddels (RBs) word in boorde aangewend in ’n poging om dit te oorkom. In kern- en steenvrugboorde vind aanwending van die RB waterstofsianamied (WS) algemeen plaas. Thidiazuron (TDZ), ’n ander RB word op beperkte skaal in appelboorde aangewend. Die uitwerking van RBs op bessierypwording, -grootte en opbrengs van SHB kultivars Bluecrisp, Emerald en Star is oor twee seisoene in ’n boord naby George ondersoek, om vas te stel tot watter mate bloubessie-oesskedulering met behulp van RB aanwending moontlik is. Na Dormex® (WS, 520 g L-1) aanwending in 2010, waarin ’n warm winter ondervind is, is die bessierypwording van ‘Bluecrisp’ versnel. Dormex® aanwendingstye voordat blomknopskubblare oopmaak, maar nadat winterkoue opgebou het, het ’n aanvaarbare opbrengs en bessiegrootte met geen blomknopskade tot gevolg gehad nie. ’n 1% Konsentrasie gee soortgelyke reaksies as ’n 2% aanwending maar teen ’n laer risiko vir blomknopskade. Lift® (TDZ, 3 g L-1) aanwending het die aantal dae tot 75% oesinsameling van ‘Star’ in 2010 verminder. Plante wat ’n laer opbrengs lewer produseer groter bessies as die wat ’n hoër opbrengs lewer. Lift® aanwending nadat blomknopskubblare oopgemaak het, het misvormde en beskadigde blomme tot gevolg gehad. Vertraging van blomknopinisiasie kan die oopmaak van blomknoppe uitstel tot na nuwe blare in die lente gevorm het. Dit kan vinniger bessie rypwording meebring as wat die geval vir sommige SHB kultivars na warm winters is. Die aanvang van blomknopontwikkeling in SHB bloubessies vind tydens lang nagte (16 ure) plaas en staan onder beheer van fitochroom. Onder beheerde toestande kan bloubessie blomknopinisiasie deur onderbreking van die lang donker (nag) tydperk (ON) in ’n lig-donker siklus onderdruk word. Die uitwerking van ON op bessierypwording, -grootte en opbrengs van ‘Emerald’ en ‘Snowchaser’ is oor twee seisoene ondersoek, om die mate waartoe oesskedulering met hierdie tegniek in ’n boord moontlik is aan te spreek. ON het nie die blomknopinisiasie onder hierdie eksperimentele toestande onderdruk nie, aangesien beide kultivars in albei seisoene kon blom en opbrengste lewer. Die effek op bessiegrootte en opbrengs was kultivar spesifiek. In 2011 is die totale opbrengs en hoeveelheid bessies per plant geoes van ‘Emerald’, deur ON verminder en dié vermindering was liniêr met toename in aantal ON siklusse.

Vaccinium cyanococcus, most commonly known as blueberry, is a fruit native to North America that is known for its unique taste and high antioxidant content. The skin, seed and juice of both organically and conventionally grown blueberry extract were analyzed for antioxidant content using both the Hydrophilic and Lipophilic Oxygen Radical Absorbance Capacity (ORAC) assays. Results from the Hydrophilic ORAC test showed that conventionally grown blue berries had a higher antioxidant capacity across all samples, while the Lipophilic ORAC assay showed that the antioxidant concentration of organically cultivated blueberry juice was highest, but conventionally grown blueberry seed and skin extract showed higher antioxidant content. The vitamin C content of both conventional and organic blueberries were analyzed using High Performance Liquid Chromatography (HPLC), where the organic blueberries showed a higher vitamin C concentration. In general, both organic and conventional blueberries are rich in antioxidants, and therefore, possess potential health benefits that require further study.

Two wild blueberry fields were selected to evaluate the impact of variable rate (VR) fertilization on crop productivity, surface and subsurface water quality. Management zones were delineated based on slope variability, and different fertilizer rates were applied according to prescription maps. Runoff collectors were place in the fields to measure the nutrient losses in surface runoff, while lysimeters were installed to evaluate the impact of VR fertilization (VRF) on subsurface water quality. The VR treatment significantly decreased phosphorus and nitrogen loadings in surface runoff as compared to uniform treatment. The concentrations of nutrients in subsurface water samples were also significantly lower for VR treatment as compared to uniform treatment. The excessive nutrients enhanced vegetative growth in low lying areas of uniform fertilization, while berry yield was less. Based on these results, it can be concluded that VRF in wild blueberry fields improved the crop productivity and potential environmental impacts. / This study was conducted to evaluate the impact of variable rate fertilization on crop productivity and surface and subsurface water quality in wild blueberry fields. Result illustrated that variable rate fertilization significantly reduce the nutrients loading in surface and subsurface water, and improved blueberry yield.

Thesis (MScAgric)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Southern highbush (SHB) blueberries are relatively new to the blueberry industry and are adapted to grow in areas with low winter chilling and therefore can be grown in the Mediterranean-type climate of South Africa. The blueberry industry in South Africa is still relatively young, but it is quickly expanding and therefore appropriate cultivation practises are becoming more important. This study mainly focuses on the appropriate fertilization practises for SHB cultivars Snowchaser and Emerald grown in an ever-greening system. Plants were cultivated in plant containers in a netted tunnel in the Paarl district of South Africa. All plants received continuous fertigation with a standard commercial nutrient solution containing nitrogen, phosphorus, potassium, magnesium, calcium and all micro-elements. Carbohydrate patterns were determined on newly established tissue culture plants at two-weekly intervals from April 2013 to June 2014 and macro nutrient patterns were determined at four-weekly intervals from May 2013 to June 2014. The phenology of these plants was also visually assessed during the sampling period. Macro nutrient content was determined for two-year old „Snowchaser‟ and „Emerald‟ plants at five phenological stages during the 2013/2014 season and nutrient losses due to harvest and pruning was recorded. The phenology of evergreen „Snowchaser‟ and „Emerald‟ SHB blueberries were very different from deciduous blueberries, to such an extent that fruit could be harvested at the end of winter to early spring. Carbohydrate patterns differed between the first and the second season. Reserve carbohydrates were accumulated in the first season, but not in the second season possibly due to the difference in photosynthate production between the seasons. Plants were significantly bigger, with higher total leaf area, in the second season and it could be that carbohydrates from current photosynthesis were enough to supply new growth, thus making reserves less important. Carbohydrates could also have been used to increase flower bud development instead of being stored as reserves in the second season. Nutrient patterns also differed between the two seasons, but nutrient accumulation was apparent in the second season and not in the first. Nutrient uptake was highest when plants were growing rapidly, emphasizing the importance of fertilizer during periods of rapid growth. Huge fluctuations in the nutrient concentration patterns in the root, shoot and leaf tissues were observed over the sampling period and could have been a result of irregular fertigation and therefore it is uncertain whether flushes in nutrient uptake was a result of higher nutrient demand by the plant. Nutrients are lost due to harvest and pruning and need to be replaced by applying the right amount of fertilizer. Nutrient uptake differs throughout the season as the demand for nutrients fluctuates and therefore fertilizers should be applied at different rates during the season. In the two-year old plants, the most nutrients were accumulated after summer pruning and before growth cessation and therefore most of the fertilization would occur during this stage. Recommendations for correcting nutrient losses due to harvest and pruning are made, together with recommendations for rate and timing of fertilizer application throughout the season. / AFRIKAANSE OPSOMMING: „Southern highbush‟ (SHB) bloubessies is ‟n relatiewe nuwe ontwikkeling in die bloubessie-industrie en is aangepas om in minder koue areas aangeplant te word en daarom kan hulle in die Meditereënse-tipe klimaat van Suid-Afrika aangeplant word. Die bloubessie-industrie in Suid-Afrika is nog relatief jonk, maar dit is vinnig besig om uit te brei en daarom raak geskikte verbouingspraktyke al hoe belangriker. Hierdie studie fokus hoofsaaklik op die geskikte bemestingspraktyke vir SHB kultivars Snowchaser en Emerald wat in ‟n immergroen sisteem verbou word. Plante is in houers in ‟n tonnel, wat met net bedek is, in die Paarl distrik van Suid-Afrika, aangeplant. Alle plante het dieselfde standaard kommersiële verreikte wateroplossing, teen ‟n konstante vloei, ontvang. Die oplossing het stikstof, fosfor, kalium, magnesium, kalsium en al die mikro-elemente bevat. Koolhidraatpatrone is in twee-weeklikse intervalle, vanaf April 2013 tot Junie 2014, vir nuut gevestigde weefselkultuurplante bepaal en makro-element patrone is in vier-weeklikse intervalle, vanaf Mei 2013 tot Junie 2014, bepaal. Die fenologie van dié plante is visueel waargeneem tydens die monsternemingsperiode. Makro-elementinhoud is vir tweejarige „Snowchaser‟ en „Emerald‟ plante by vyf fenologiese stadiums tydens die 2013/2014 seisoen bepaal en die voedingstofverliese as gevolg van oes en snoei is bepaal. Die fenologie van immergroen „Snowchaser‟ en „Emerald‟ SHB bloubessies het opmerklik verskil van bladwisselende bloubessies, tot so ‟n mate dat vrugte al teen einde winter na vroeë lente geoes kon word. Koolhidraatpatrone van die eerste en tweede seisoen het verskil deurdat reserwe koolhidrate in die eerste seisoen opgebou het, maar nie in die tweede seisoen nie, moontlik as gevolg van die verskil in fotosintaatproduksie tussen die twee seisoene. Plante was opmerklik groter, met groter blaaroppervlak, in die tweede seisoen en dit kon wees dat koolhidrate van huidige fotosintese genoeg was om die groei te onderhou en sodoende die afhanklikheid van reserwes te verminder. Koolhidrate kon ook vir verhoogde blomknopontwikkeling gebruik geword het, in plaas van om as reserwes vir die tweede seisoen gestoor te word. Voedingstofpatrone het ook tussen seisoene verskil, maar voedingstofakkumulasie was duidelik in die tweede seisoen en nie in die eerste nie. Voedingstofopname was die hoogste wanneer plante vinnig gegroei het en daarom is bemesting tydens periodes van vinnige groei uiters belangrik. Groot wisselinge in die voedingstofkonsentrasiepatrone van die wortels, lote en blare is tydens die monsternemingsperiode waargeneem en onreëlmatige verrykte watertoediening kon dit veroorsaak het. Daarom is dit onseker of fluktuasies in voedingstofopname ‟n gevolg was van hoër voedingstofaanvraag deur die plant. Voedingstowwe gaan verlore deur oes en snoei en moet deur die toediening van korrekte bemesting vervang word. Voedingstofopname verskil oor die verloop van die seisoen soos die aanvraag vir voedingstowwe deur die plant verander en daarom moet bemestingstowwe teen verskillende hoeveelhede deur die seisoen toegedien word. In die tweejarige plante is meeste van die voedingstowwe ná somersnoei en voor groeistaking opgeneem en daarom moet meeste van die bemesting tydens hierdie stadium toegedien word. Aanbevelings vir die korrigering van voedingstofverliese as gevolg van oes en snoei, tesame met aanbevelings vir die hoeveelheid en tyd van bemestingstoediening deur die seisoen, word gemaak.

There is very low tolerance for blueberry maggot (Rhagoletis mendax Curran) in blueberries making it a serious pest in eastern North America. Control is focused on eliminating flies with insecticides before oviposition in fruit. Organic mulches may improve highbush blueberry production, but their effects on this pest are largely unknown. The research in this thesis evaluated compost and pine needle mulches on blueberry maggot (mature maggots, pupae, emerging flies) and predatory beetles that may consume these stages. Mulches affected fly emergence and maggot pupation. Fly emergence was reduced by 80-100% and delayed ~8 days from pupae covered with 20 cm of pine needles compared to 1 cm of soil. Emergence from 20 cm of compost was lower in wet conditions, and 5 cm of mulch did not limit emergence in the field. Pupation at increased depth reduced emergence because flies did not eclose or, if eclosed, were unable to crawl to the surface. The delay was likely due to lower temperatures at depth. No flies emerged from 1 cm in pine needles in the field probably due to high temperatures. In the laboratory, maggots pupated more deeply in pine needles than other substrates, but ~30% did not pupate in dry pine needles. Saturated soil caused ~50% of maggots to pupate on the surface. Mulching altered beetle diversity and activity/density and affected beetle predation on maggots and pupae. Compost plots in a highbush blueberry field attracted predatory carabids and staphylinids, although some staphylinids were frequent in pine needles and phytophagous carabids preferred unweeded compost plots. Attraction to compost, particularly for Pterostichus melanarius (Illiger), was due primarily to higher prey densities - earthworms and millipedes - than other treatments. This beetle consumed some maggots or pupae in soil or compost, but predation rates decreased when alternative prey was abundant. Blueberry bushes in weedy compost plots attracted many flies, but infestation rates were higher in composted bushes only in the year mulch was applied. Overall, thick mulching with pine needles contributes most significantly to blueberry maggot management. Future research should explore integration of mulch with other tactics for R. mendax control.

Weeds are considered a major problem for organic wild blueberry (Vaccinium angustifolium Ait.) production due to their excessive growth and limited management options available. Therefore, the primary objective of this study was to investigate burning in combination with sulphur application as a weed management option for organic blueberry production. In addition, Finalsan® and EcoclearTM as potential candidates for perennial weed control in organic production were evaluated. Burned and sulphur plots produced higher blueberry stem density, blueberry cover and yield compared to mowed and no-sulphur plots, respectively, although, the interaction was not significant. Similarly, low weed density and cover were observed in burning and sulphur application plots. Mycorrhizal colonization in blueberry roots was significantly higher in burned plots than mowed plots. A single application of Finalsan® and EcoclearTM effectively controlled goldenrod, sweet fern and bracken fern. However, a single application of either product did not control wild raisin or moss.

No description available.

Blueberry, Cherry and Raspberry (berry) production is a potential alternative land use opportunity in the Limpopo Province (LP) of South Africa (RSA). RSA based site selection criterion and literature is limited. Haenertsburg and an area near Pietersburg (Polokwane) were identified for berry production potential. In Haenertsburg, most viable land is held by the timber industry. In Pietersburg, soil and climatic conditions vary greatly, representing a site selection risk. Using accepted site selection processes, a study was conducted which identified the need to select land qualities and characteristics (QC’s) appropriate to berry production. The study revealed key QCs’ and secondary QCs’. Key QCs’ must be adhered to for site selection, while secondary QCs’ have site-specific application. The key land qualities are climate, soil, water, topography and management. In order to design a land rating system (LRS), specific characteristic values were cataloged per quality and per berry. Characteristic values were assigned to a land rating system where S1 (highly suitable), S2 (moderately suitable), S3 (marginally suitable), N1 (currently not suitable) and N2 (not suitable). To test the LRS, a real, but non-representative resource assessment (RA) took place. The RA revealed the further need to incorporate land limits into site selection. QCs’ and land limit data was collected from existing sources and measured in situ where the data was insufficient. Finally the RA data was applied to the LRS through the process of matching. The matching precipitated the formation of a site selection process or tool, presented on tables. Each table represents a land quality. Water and soil criteria varied per berry, while topography, water and management were common to all three berries. Additionally, the site selection tool enabled the assessment of secondary QCs’. The assessment process is conservative, allocating the lowest land rating as the overall rating. This allows for the land user to address the most limiting factor from worst to least, thereby ensuring sustainable and good land use. / Dissertation (MInstAgrar (Land-Use Planning))--University of Pretoria, 2008. / Plant Production and Soil Science / unrestricted