The anatomy of bifurcations in trees requires further scientific investigation as the current anatomical model for them is logically flawed. The provision of a better model will assist in scientific studies of woody plants, the risk assessment of junctions in mature trees and provide bio-inspiration for Y-shaped joints in composite materials. In this study, the xylem formed in the central axis of a hazel (Corylus avellana L.) bifurcation is shown to provide a disproportionately greater amount of its tensile strength. CT scanning identified that this centrally-placed xylem was 28.1% denser, with 63% less vessels formed in this tissue, such vessels being 50.5% of the diameter and 32.5% of the length of those formed in adjacent stem tissues. The wood grain pattern at the bifurcation apices were 22 times more tortuous, forming interlocking patterns that acted to resist tensile forces by requiring the extraction or breaking of wood fibres along their length (the axial tensile strength of wood). Subsequent tests confirmed that this conferred more than 100% additional tensile strength to these specialised xylem tissues. These findings provided the basis of a novel anatomical model for bifurcations in woody plants. Further to this, the effects of several factors upon junction strength and biomechanical behaviour were assessed in bifurcations of hazel, identifying the weakening effect of bark inclusions and three types of artificial modification as well as differences in wind-induced movement between bifurcation types. This study concludes that further investigations of bifurcations in a wider range of woody plants and observations of the developmental stages of the interlocking wood grain patterns found at bifurcations would usefully add to existing knowledge.

Les nématodes gastrointestinaux (NGIs) représentent une contrainte majeure en élevage des ruminants. Jusqu’à présent, la maîtrise de ces parasitoses a reposé essentiellement sur l’emploi répété de traitements anthelminthiques (AH) de synthèse. Cependant, le développement constant de résistances aux AH dans les populations de nématodes chez les petits ruminants conduit à rechercher des méthodes alternatives ou complémentaires de lutte contre ces parasitoses. Au cours des deux dernières décennies, les données se sont accumulées montrant que certaines plantes étaient dotées de propriétés anthelminthiques, ce qui a été associé à la présence de tannins condensés (TCs) et de flavonoïdes. Ces ressources contenant des TCs, exploitées comme nutricaments, représentent donc une alternative attractive à la chimiothérapie, en combinant des effets bénéfique sur la santé et la nutrition des ruminants. Toutefois, une des difficultés à résoudre, pour un usage pertinent de ces nutricaments, est de comprendre l’origine de la variabilité des résultats observés dans l’activité AH. A côté de facteurs quantitatifs, la qualité (la structure) des TC semble également jouer un rôle dans les propriétés antiparasitaires mais ce facteur demeure peu exploré. En utilisant Haemonchus contortus comme modèle expérimental de nématode et le sainfoin (Onobrychis viciifolia) comme modèle de plantes contenant des tannins, l’objectif général de cette thèse a été de mieux comprendre les relations structure/activité des TCs. Les objectifs spécifiques des diverses études menées ont été 1) d’ examiner in vitro (par la méthode LEIA) l’activité AH de 36 fractions purifiées de TCs présentant une large diversité de caractéristiques structurelles [ex: la taille (mDP), les proportions prodelphinidols /procyanidols (PD/PC) et trans/cis ], et 2) le rôle possible d’interactions entre tannins et flavonoïdes, 3) d’ évaluer et comparer in vivo chez des agneaux, les conséquences sur les populations de vers et sur la résilience de l’hôte de la distribution de 2 ressources contenant des TCs de qualité contrastée pour les valeurs PD/PC [fort PD/PC, sainfoin (O. viciifolia); bas PD/PC, pellicules de noisettes (Corylus avellana)], 4) d’ examiner si les résultats varient en fonction de l’espèce et de la localisation des parasites (abomasum, H. contortus vs intestin grêle, Trichostrongylus colubriformis), 5) d’évaluer les concentrations, la qualité et la bio-disponibilité des TCs le long du tube digestif chez les ovins. Les résultats acquis ont montré: 1) des relations in vitro entre certaines caractéristiques des TCs et l’activité AH : un rapport élevé PD/PC pour les 2 espèces de nématodes auquel s’ajoute un rôle de la taille des tanins (mDP) pour H. contortus sont les facteurs identifiés. De manière générale, H. contortus s’est avéré plus sensible (valeurs EC50 plus faibles) aux effets des diverses ressources que T. colubriformis. Des synergies d’effets AH ont été observés entre tannins et flavonoides (quercétine et lutéoline), tout particulièrement dans le cas de TCs avec un faible rapport PD/PC. Dans l’étude in vivo, les agneaux consommant du sainfoin ont montré des effets AHs et une amélioration de la résilience de l’hôte alors que les effets de la noisette ont été beaucoup plus discrets. Les analyses menées sur les contenus des divers organes digestifs et les fèces, pour les deux types de ressources ont montré de fortes réductions de TCs détectés par rapport aux teneurs initiales dans la ration alors que les caractéristiques de structure étaient globalement préservées au long du tube digestif. En conclusion, le rôle de la qualité (structure) des TCs dans l’activité AH a été confirmé à la fois par les études in vitro et in vivo. Ces résultats suggèrent l’importance de prendre en compte ces facteurs dans la recherche de ressources pouvant être exploitées comme futurs nutricaments chez les ruminants. / Gastrointestinal nematodes (GINs) represent a major threat for the breeding and production of grazing ruminants. So far, their control has been based mainly on the repeated use of synthetic AH drugs. However, worm populations in small ruminants have consistently developed resistance against all AH drugs. In the search for alternative solutions to such drug treatments, the last two decades have provided evidence that some plants possess natural AH bioactivity. This has been related to the presence of condensed tannins (CTs) and flavonoids. Therefore, CT-containing resources represent a promising alternative to chemotherapy especially when used as nutraceuticals that combine beneficial effects on health and nutrition in small and large ruminants. However, one of the main constraint to use these nutraceuticals relates to the variations in AH results. The structural features (quality) that contribute to the AH activities of CTs remain elusive. By using the GIN Haemonchus contortus as a experimental model of nematode and Onobrychis viciifolia as a model of CT-containing plant, the general aim of this PhD was to better understand the structure/activity relationship of CT. The specific objectives were i) to examine in vitro (LEIA) the AH activity of 36 purified CT fractions with a wide range of structural features [i.e. size (mDP), prodelphinidin/procyanidin (PD/PC) and trans/cis ratios], and ii) the possible role of interactions between tannins and flavonoids, iii) to evaluate in vivo the AH activity and host resilience of two CT-resources with contrasting PD/PC ratios (i.e. high PD/PC, O. viciifolia; low PD/PC, Corylus avellana), iv) to examine whether these results vary depending on the parasites species (abomasal, H. contortus vs intestinal, Trichostrongylus colubriformis), v) to examine the CT availability (quantity and quality) along the digestive tract in sheep. In regard of CT features and AH activity, in vitro correlations were observed between AH activity and high PD/PC for both species. mDP was an additional criteria for H. contortus. Lower EC50 values were assessed for H. contortus. Synergistic AH effects were observed between CT and flavonoids (quercetin and lutein), and they were higher with fractions of low PD/PC ratios. In vivo, the lambs consuming sainfoin pellets showed consistently higher AH effects and improvement in the host’s resilience. Analyses of digesta samples and faeces, for both diets showed large reduction of detected CT related to the feed, whereas the CT structures seem preserved along the gut. In our studies, the role of CT structural features in the AH activity was observed both in vitro and in vivo. These results confirmed the influence of CT quality in the AH effects, and underline the relevance of taking these factors into account when screening CT resources as potential nutraceuticals in small ruminants.

<p>The great difference in the level of chloroplast variation and its geographic structure among the three main species studied here demonstrates that forest species do not form a homogeneous group. Hazel shows a genetic structure similar to many other thermophilous species and this structure, in combination with fossil evidence, indicates that the post-glacial colonisation of most of Europe originated in a refugium in western France while the Balkan and Italy were colonised from a south-eastern refugium.</p><p>In sallow and silver birch the chloroplast DNA variation and its structure does not fit with a scenario of glacial restriction to southern refugia and survival at intermediate latitudes is suggested for both species. The chloroplast DNA variation in silver birch suggests the presence of one western and one eastern European post-glacial colonisation route and limited contribution of southern populations in the colonisation of the rest of Europe. Unique haplotypes by the Ural Mountains indicates the possibility of a separate glacial origin of these populations.</p><p>The study of chloroplast DNA in species closely related to sallow and silver birch indicate that extensive hybridisation and cytoplasmic gene flow occurs within both the Salix and Betula genera in Europe. The nuclear and chloroplast phylogenies of 14 Betula species were not in complete agreement with each other or with the classical division of the Betula genus into subgenera or sections. The phylogenetic structure implies that hybridisation has played a role in the evolution of the Betula genus.</p><p>This thesis focuses on the chloroplast DNA variation in three forest tree genera: Corylus, Betula and Salix. Chloroplast PCR-RFLP is used to evaluate the post-glacial history of hazel, Corylus avellana, silver birch, Betula pendula and sallow, Salix caprea and to explore the possibility of introgression in the Salix and Betula genera. In addition, the chloroplast matK gene, its flanking regions and the nuclear ADH gene were used to study the phylogenetic relationships within the Betula genus.</p>

The great difference in the level of chloroplast variation and its geographic structure among the three main species studied here demonstrates that forest species do not form a homogeneous group. Hazel shows a genetic structure similar to many other thermophilous species and this structure, in combination with fossil evidence, indicates that the post-glacial colonisation of most of Europe originated in a refugium in western France while the Balkan and Italy were colonised from a south-eastern refugium. In sallow and silver birch the chloroplast DNA variation and its structure does not fit with a scenario of glacial restriction to southern refugia and survival at intermediate latitudes is suggested for both species. The chloroplast DNA variation in silver birch suggests the presence of one western and one eastern European post-glacial colonisation route and limited contribution of southern populations in the colonisation of the rest of Europe. Unique haplotypes by the Ural Mountains indicates the possibility of a separate glacial origin of these populations. The study of chloroplast DNA in species closely related to sallow and silver birch indicate that extensive hybridisation and cytoplasmic gene flow occurs within both the Salix and Betula genera in Europe. The nuclear and chloroplast phylogenies of 14 Betula species were not in complete agreement with each other or with the classical division of the Betula genus into subgenera or sections. The phylogenetic structure implies that hybridisation has played a role in the evolution of the Betula genus. This thesis focuses on the chloroplast DNA variation in three forest tree genera: Corylus, Betula and Salix. Chloroplast PCR-RFLP is used to evaluate the post-glacial history of hazel, Corylus avellana, silver birch, Betula pendula and sallow, Salix caprea and to explore the possibility of introgression in the Salix and Betula genera. In addition, the chloroplast matK gene, its flanking regions and the nuclear ADH gene were used to study the phylogenetic relationships within the Betula genus.

The black truffle (Tuber melanosporum Vitt.) industry in Australia is relatively new and has enormous potential but some truffières (truffle farms) fail to meet anticipated harvest projections. Inappropriate soil conditions and climate, and the management of such factors are suggested as the primary reasons for inadequate yield. In addition, requirements for ascocarp initiation and development and the role of the host plant in such processes are unknown. This study examines interactions between European hazel (Corylus avellana L.) and the ectomycorrhizal (ECM) black truffle symbiont in a commercial truffière (Hazel Hill) in south-western Australia. Specific studies were initiated to examine the interactions of host physiology, mycorrhizal infection and the interaction with abiotic factors. The study related specific physiological processes of the host plant to the known life cycle of the black truffle to determine the role of the host plant in ascocarp production, if any. The work also examined the effect of silvicultural treatments intended to increase truffle production. A review of existing literature was undertaken to determine the key soil and climatic factors required for successful truffle production. Climatic conditions appeared more important than soil chemistry and structure in Western Australia, with significant seasonal variation in air and soil temperatures required plus irrigation to supplement summer rainfall. This information was used to define areas with potential for truffle production in the south-west of Western Australia: the cooler, high rainfall regions (>1000 mm annual rainfall) where there is sufficient seasonal variation in soil temperature and availability of adequate quantities of quality water for irrigation. Subsurface soil acidification and salinity, as well as groundwater salinity, are constraining factors. Lime amendment is necessary to create sufficiently high pH and CaCO3 levels required by the truffle fungus. A field trial was established to monitor the seasonal C dynamics of European hazel in the context of the life cycle of the black truffle. Maximum translocation of sucrose in the phloem sap coincided with the period of anticipated rapid growth of the truffle ascocarp implicating the use of current photosynthate in C nutrition of the ascocarp. Sampling of non-structural carbohydrates (NC) of above and belowground plant material indicated maximum storage of C in the host coincides with maturation of the ascocarp. These observations provide evidence of a synchronous growth habit of the plant host and the ascocarp. The C allocation patterns of European hazel in response to liming a loamy soil, taken from near the Hazel Hill truffière, and inoculation with ECM fungi (T. melanosporum, Hebeloma sp. and Scleroderma sp.) were examined in a glasshouse pot trial. Liming increased biomass allocation to the shoot and induced deficiencies of phosphorus and manganese. Colonisation by ECM fungi significantly increased net photosynthesis, indicating the sink strength of these fungi, but there was no relationship between the level of mycorrhizal infection and fine root NC. The maximum rate (40 g lime kg-1 soil) reduced infection by Hebeloma and Scleroderma and had no impact on T. melanosporum. Further, infection rates of T. melanosporum did not increase in response to lime suggesting lime is not necessary for ECM development in this soil type. Fertiliser is widely used in commercial truffières in Australia but the consequences for truffle production are unknown. In a field trial, the growth and physiological response of European hazel to forms of phosphorus (34 and 68 kg ha-1 apatite-P and 68 kg ha-1 triple super phosphate -P) and nitrogen (50 kg ha-1 of NO3- and NH4-N) were examined as well as the mycorrhizal response to fertiliser. Apatite-P increased phloem sap sucrose concentrations which was attributed to increased root biomass and associated sink capacity. Fertiliser application did not change fine root NC concentrations suggesting no increase in allocation of C to ECM structures. The highest rate of apatite-P decreased mycorrhizal infection rates of T. melanosporum and, most likely, was the result of increased infection rates of Hebeloma. In contrast to the literature relating to indigenous Australian ECM fungi, the highest rate of soluble-P did not decrease ECM infection rates in T. melanosporum. Nitrogen treatments increased foliar N content and improved gas exchange efficiency of plants, and had no adverse impact on the level of ECM infection. Fertilisation with N significantly increased soil respiration rates suggesting N limits mineralisation at this site. Some truffières manage the canopies of the host tree to ensure maximum exposure of the soil surface in order to increase soil temperatures. As there are no published data on the effect of pruning on black truffle production, a field trial was established to document the impact of canopy pruning on host physiology and soil temperature. The removal of 65% of canopy leaf area reduced phloem sap sucrose concentrations, soil respiration rate and the soluble: insoluble NC ratio of fine roots in the short term (1-3 weeks). There was no compensatory response of leaf gas exchange parameters as a result of pruning. Generally, there was no long term impact on plant physiological parameters as a result of pruning. Long term effects on soil temperature were observed as a result of pruning. Mean annual temperature and amplitude increased significantly beneath pruned trees and spring, summer and autumn soil temperatures increased as did diurnal variation as a result of pruning. Pruning did not increase winter soil temperatures and therefore would probably not impact on ascocarp maturation during this period. This research has provided insight into the C physiology of hazel associated with the black truffle and the consequences for truffle production. The results provide anecdotal evidence of direct C transfer between the host and the developing truffle, contrary to the existing paradigm that the ascocarp is saprotrophic for the majority of its growth and development. There is a need to validate this finding as there are consequences for management of commercial truffières. Liming of loam duplex soils can reduce the abundance of the most common competitor ECM fungi and should be encouraged in commercial truffières. Applying phosphorus and nitrogen to commercial truffières will improve growth rates of planted trees without adversely impacting on ECM infection by black truffle fungi, although the impact on truffle production remains unknown. It is anticipated truffle production will improve in the longer term as a result of pruning and prudent canopy management. Management options should include tree removal to reduce planting density and increase soil exposure in truffières. There is a need for longer term trials to be established to determine the C nutrition of the truffle ascocarp and to clearly define the key stages of the black truffle life cycle in Western Australia.

Magistro darbe tiriama paprastojo lazdyno formų: “X”, “Aurea”, “Fuscorubra” ir paprastojo lazdyno (Corylus avellana L.) mikrodauginimo in vitro sąlygos, bei augalų – regenerantų išauginimas. Darbo objektas – paprastojo lazdyno tiriamosios formos: “X”, “Aurea”, “Fuscorubra” ir paprastasis lazdynas (Corylus avellana L.). Darbo metodai – eksplantų parinkimas, paruošimas ir sodinamosios biologinės medžiagos išsterilinimas. Maitinamosios terpės eksplantų auginimui ir rizogenezei parinkimas. Eksplantų prigimties įtaka morfogenezei audinių kultūroje. Genotipo įtaka augalų regeneracijai audinių kultūroje. Auginimo salygų in vivo nustatymas. Darbo rezultatai. X lazdyno ir paprastojo lazdyno eksplantus siūloma sterilinti bet kuriuo iš tirtų metodų. Raudonlapio lazdyno eksplantus rekomenduojame sterilinti metodu Nr. 2, kai veiklioji medžiaga - H2SO4 85 , o geltonlapio lazdyno eksplantus - metodu Nr. 1 su AgNO3 0,1 . Visų genotipų lazdyno pumpurams sterilinti netinka sieros rūgštis (85 ). Paprastojo lazdyno formoms dauginti in vitro būdu tinkamiausia modifikuota WPM I varianto maitinamoji terpė, o paparastajam lazdynui - modifikuota WPM III varianto maitinamoji terpė. Corylus genties morfogenezė audinių kultūroje priklauso nuo genotipo. Genotipas taip pat turi įtakos susidariusio kaliaus spalvai. Daugiausiai eksplantai paaugo nuo 10 iki 20 dienos. Geriausius rezultatus pasiekė X lazdyno genotipas, nes paaugo nuo 3 iki 26 mm. Kultivuojant in vitro sąlygomis, geltonlapio lazdyno... [toliau žr. visą tekstą] / Micropropagation in vitro conditions and the production of plants – regenerants of hazel forms "X", "Aurea", "Fuscorubra" and plain hazel (Corylus avellana L.) are investigated in the work of master science. Objectof the work - hazel test forms "X", "Aurea", "Fuscorubra" and plain hazel (Corylus avellana L.). Methods of the work - Explants selection, preparation and sterilization of planting biological material. The choice of nutrient medium for explants cultivation and rhizogenesis. Impact of explants nature on the morphogenesis in tissue culture. Genotype influence to the regeneration of the plant in tissue culture. Determination of the conditions of in vivo cultivation. The results of the work. “X” form and plain hazelnut explants are suggest to be sterilized using method No 2, the active ingredient - 85 H2SO4, "Aurea" hazel explants - method No 1, with AgNO3 0,1 . Modified WPM I nutrient medium is the best version for in vitro propagation of the hazel forms, modified version of the WPM III nutrient medium – for plain hazelnuts. Morphogenesis of the Corylus genus in tissue culture depends on the genotype. Genotype also affects the color of the callus formed. Explants grew most in the period of 10 - 20 days. Best results were achieved by “X” hazelnut genotypes which grew from 3 to 26 mm. During the cultivation in in vitro conditions "Aurea" hazelnut explants did not form the yellow plates. The other 3 genotypes were more than 50  of identical micro shoots. “X”... [to full text]

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European hazelnut is a significant crop in the Pacific Northwest, and the US ranks 4th internationally for hazelnut production. Production in the Pacific Northwest is threatened, however, by the disease eastern filbert blight (EFB) caused by the fungus Anisogramma anomala (Peck) E. Müller. To meet the challenges faced by the hazelnut industry in Oregon and Washington, the breeding program at Oregon State University has focused on developing DNA marker technology and producing EFB resistant cultivars. This study focused on developing new microsatellite markers from hazelnut transcriptome sequences and on disease resistance from three accessions ('Culpla,' 'Crvenje,' and OSU 495.072) which showed no disease symptoms following a series of inoculations. DNA markers have been useful in hazelnut breeding for marker-assisted selection, construction of genetic linkage maps, cultivar fingerprinting, and phylogeny studies. Previously developed markers include AFLP, RAPD, ISSR, and microsatellite (SSR) markers developed from enriched libraries and ISSR fragments. This study utilized the transcriptome sequence from 'Jefferson' hazelnut to mine for microsatellites, align with the genomic sequence, design primers, screen for polymorphism, and characterize and map polymorphic markers. A total of 1432 microsatellites were mined from the transcriptome sequence, and the most frequently found motifs were AG (35.8%), AT (13.3%), and AAG (12.7%), and 382 primer pairs were designed. Screening showed that 119 markers were polymorphic, and these were characterized on sets of 50 and 14 accessions. Fifty-three markers that segregated in the mapping population or in three alternate populations were mapped and assigned to linkage groups. A dendrogram showed that accessions clustered mostly according to geographic origin. These results confirm the high level of diversity present in hazelnut, and the markers developed in this study will be useful for further genetics studies in hazelnut. The three EFB resistant parents 'Culpla,' 'Crvenje,' and OSU 495.072 were subjected to two inoculation treatments: greenhouse inoculations and exposure under an inoculation structure. The accessions remained free of disease after both treatments. Progeny segregating for resistance were produced. The progeny were inoculated either in the greenhouse or under the structure, and disease response recorded for each individual. DNA was extracted from seedlings, and sets of 32 seedlings from each resistant parent were screened with previously mapped markers using PCR and capillary electrophoresis. All three resistance sources were correlated with marker A614, allowing the resistance loci to be assigned to linkage group (LG) 6. The progeny were then screened with all known microsatellite markers on LG 6, and linkage maps constructed of the marker loci and resistance loci. Markers KG821, LG628, and LG696 are especially close to the resistance loci and will be useful for marker-assisted selection. Although these resistance loci are located in the same region of LG 6 as the 'Gasaway' resistance gene, they are different from 'Gasaway,' and markers linked to resistance will be useful for introgressing and pyramiding resistance in new cultivars. / Graduation date: 2013

Le principali anomalie evidenziate nelle nocciole avariate riguardano la presenza di macchie necrotiche, imbrunimenti interni rilevati inseguito al taglio dei frutti e la presenza di marciumi parziali o totali su di essi con conseguente riduzione del prodotto disponibile sul mercato e ingenti perdite economiche. Sulla base di quanto premesso, lo scopo principale di questa tesi è stato quello di identificare e caratterizzare l'agente causale/i dei difetti del nocciolo e di definire un protocollo di gestione del problema, secondo i principi IPM. È stata quantificata l'incidenza dei generi fungini isolati da nocciole provenienti da diverse aree geografiche (Caucaso e Turchia), raccolte in diversi anni e in diverse fasi di crescita della coltura. Diaporthe è stato identificato come il principale genere fungino associato ai difetti della nocciola, e la caratterizzazione molecolare ha confermato il ruolo predominante della specie D. eres. Sono state studiate le caratteristiche ecologiche di questo fungo e l'efficacia in vitro di fungicidi chimici e biologici per controllarne la crescita miceliale, lo sviluppo di picnidi e la formazione di cirri. I risultati ottenuti costituiscono una base per definire linee guida per la corretta gestione della coltura al fine di prevenire la comparsa del patogeno identificato e delle difettosità nelle nocciole / Defects on hazelnuts are responsible for a significant reduction in the availability of high-quality hazelnuts with profound economic impacts. A reduction in the occurrence of defects, based on the identification of causal agents and on their control, is critical to improve the quality of raw nut products and reduce yield losses. Based on this background, the main aim of this thesis was to identify and characterize the causal agent/s of kernel defects in hazelnuts and to define a management protocol, according to IPM principles. Defects affecting hazelnuts are cause of brown spots on the kernel surface and darkening/browning inside the kernel, visible after nuts are half-cut. The incidence of fungal genera in hazelnuts coming from different geographical areas (Caucasus and Turkey), collected in different years at different crop growth stages, was quantified. Diaporthe was identified as the main genus involved in hazelnut defects, and the molecular characterization confirmed the predominant role of D. eres. Its ecological needs were investigated, and the in vitro efficacy of chemical and biological fungicide were screened to control D. eres growth, pycnidial conidiomata development and cirrhi occurrence. This would be an essential tool for a sustainable crop protection approach in this economically important crop

Eriophyoid big bud mites are key pests of hazelnuts throughout the world, although little is known of the identity and impact of the species on New Zealand hazelnut crops. The key objectives of this study were to determine the species of mite present on New Zealand crops, explore a method of monitoring mite emergence from overwintering big buds, determine the phenology of mites in relation to tree phenology and weather, and identify the optimum timing for control measures. The presence of both Phytoptus avellanae (Nalepa 1889) (Acari: Phytoptidae) and Cecidophyopsis vermiformis (Nalepa 1889) (Acari: Eriophyidae) was confirmed, the latter species being a new record for New Zealand. Preliminary diagnostic DNA sequences were determined for both species. A sticky band technique was developed to monitor mite emergence from overwintering big buds, and mite emergence was found to occur between early and late spring. Mite emergence and movement occurred when daily temperatures were greater than 15 degrees C and when mean temperatures were greater than 9 degrees C, with mite emergence increasing with temperature. It proved difficult to relate the phenology of hazelnut to mite emergence, however, the development of new buds during mite emergence was a crucial factor in the infestation of new buds. An accumulated heat sum model (DD), started at Julian date 152 and using a lower threshold temperature of 6 degrees C, predicted the onset of emergence on two cultivars and at two sites as occurring at approximately 172 DD. A regression model based on leaf number, bud height, bud width, DD and Julian date provided a more satisfactory prediction of percent accumulated mite emergence. It is recommended both peak mite emergence and the appearance of hazelnut buds should be used to optimise the time to apply control measures. Therefore, a control should be applied before buds measure 0.5 x 0.5 mm (width x height), are enclosed within the axil, and have a rounded tip, or, when 50% accumulated mite emergence has occurred, which ever occurs first. A preliminary field experiment tested the application of sulphur (40 g/10 litres of 800 g/kg No Fungus Super Sulphur) at 2, 50 and 80% accumulated mite emergence. The greatest reduction in mite numbers was achieved with an application at approximately 50% emergence. Considerable variation in mite emergence occurred between years, therefore optimum timing of controls would need to be determined by monitoring mites, new buds and weather conditions each year. Field collection of mites also identified the presence of Typhlodromus doreenae Schicha (Acari: Phytoseiidae) which would warrant further study for inclusion in an integrated mite control programme.