Please read the abstract in the section 00front of this document / Dissertation (MSc)--University of Pretoria, 2005. / Microbiology and Plant Pathology / Unrestricted

The fungal genus Botryosphaeria including its anamorphs has a cosmopolitan distribution and occurs on a wide range of monocotyledonous, dicotyledonous and gymnospermous hosts, including woody twigs and branches, herbaceous leaves, stems of grasses, and even lichen thalli. These fungi give rise to a wide variety of symptoms such as shoot blights, stem cankers, fruit rots, die-back and gummosis. They are also known as saprophytes on dead or dying stems, branches or leaves of plants. In Venezuela, the following species have been reported: Lasiodiplodia theobromae (the anamorph of Botryosphaeria rhodina), Diplodia pinea. D. mutila and Dothiorella spp. However, their characterization has been based only on morphological descriptions. The most common and well characterized species. L. theobromae, is associated with pines and other hosts. The focus of the studies presented in this thesis as to survey Eucalyptus and Acacia plantations in Venezuela for the presence and influence of Botryosphaeria spp., and to characterize these fungi using morphological characteristics and DNA sequence data. I also evaluated the pathogenicity and population biology of Botryosphaeria species present in the plantations. It was anticipated that the various studies would characterize a relatively large number of Botryosphaeria species, potentially recognize new species and provide some perspective of their relative importance to the Eucalyptus growing industry. The thesis has been divided into chapters that reflect discrete units prepared for future publication. The first chapter presents a review of the relevant literature. Two chapters treat the taxonomy of the Botryosphaeria spp. collected in this study. An additional two chapters consider the population biology of the most commonly encountered species and the remaining chapter deals with the pathogenicity of these fungi to Eucalyptus. In the literature review I treat the taxonomy of Botyosphaeria, which has been the subject of much uncertainty for many years. I also briefly review recent findings related to their molecular characterization. A focus is also placed on the pathogenicity of Botyosphaeria species on various host plants and their known importance in Venezuela. The focus concerns mainly Eucalyptus spp. Surveys that formed part of this study logically gave rise to a large collection of Botryosphaeria isolates. An important component of this thesis was to characterize these fungi. This was done based on morphological characteristics and also comparisons or DNA sequence data for various gene regions known to be informative for these fungi. Lasiodiplodia theobromae (anamorph of B.rhodina), B. ribis and B. parva were studied from a population biology perspective. These fungi were chosen for study because they were the most common species encountered on Eucalyptus in Venezuela. To study populations, I made use of simple sequence repeat markers (SS R). Three populations of each of L. theobromae (Venezuela, Mexico and South Africa) and B.ribis-B. parva complex (Venezuela, Colombia and Hawaii) were analysed and the data considered in terms of population differentiation, gene now, mode of reproduction, gene and genotype diversity. In the final chapter of this thesis, I evaluated the pathogenicity or the seven Botryosphaeria species identified from Venezuela. These seven species were thus inoculated on Eucalyptus urophylla x E. grandis hybrid clones. A second series of inoculations was then carried out with the two most pathogenic fungi to determine the relative tolerance or the most important clones to infection. This thesis was conducted over a period of four years. Work was undertaken both in Venezuela and South Africa and this necessitated long periods of time away from my home University and family. Surveys were conducted in many parts of Venezuela to collect the Botryospaeria spp. of interest for latter study in South Africa. The research chapters have been completed systematically and they evolved over time. Each represents a discrete unit implying that there is some overlap, at least in the references, between them. I would like to believe that the thesis will provide a firm foundation for further studies of Botryospaeria spp. and prove valuable to the small but important Eucalyptus growing industry in Venezuela. / Thesis (PhD)--University of Pretoria, 2008. / Microbiology and Plant Pathology / unrestricted

vi, 207 leaves : graphs, tables, photos ; 30 cm / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Entomology, 1980

Bibliography: leaves 137-167 / viii, 189 leaves, [31] leaves of plates : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Entomology, Waite Agricultural Research Institute, 1986

In South Africa the genus, Eucalyptus plays an important role as a major economic component in the forest and mining sector. Unfortunately, this genus has problems due to damage by pests. The Eucalyptus snout beetle, Gonipterus scutellatus, feeds and defoliates the leaves of eucalypts. Plants produce secondary metabolites, which protects them against defoliation by insects and herbivores. This study focuses on the variations of total soluble phenolic content of nine Eucalyptus species between the species and within the species throughout the year. Total soluble phenols were quantified with the Folin-Ciocalteau reagent. There was a general increase in the concentration of total soluble phenols throughout the year. The content of total soluble phenols were generally higher compared to carbohydrates. This experiment needs to be done on a continuous basis so as to formulate a screening method for eucalypt species that are resistant to G. scutellatus. / Dissertation (M Inst Agrar (Sustainable Insect Management))--University of Pretoria, 2005. / Zoology and Entomology / unrestricted

In South Africa, the genus Eucalyptus plays an important role as a plantation tree and hence forms a major economic component in the forest sector. An insect pest of these Eucalyptus species, Gonipterus scutellatus, causes periodic defoliation in the plantations. Plants have extraordinary array of chemicals (secondary metabolites), which defend them from herbivores. This study reports on the seasonal variation of the tannin concentration and carbohydrate content of the leaves of nine Eucalyptus species. Soluble tannins were quantified using Hagerman test and the carbohydrate content with a refractometer. Generally high tannin concentrations were observed during spring and late summer with low concentrations during autumn and winter. During the months of February, April, July tannin concentration was usually found to be higher than the carbohydrate content. The higher concentration of tannin could be linked to the allocation of carbon for the production of tannin instead of carbohydrates for growth. / Dissertation (MInst Agrar)--University of Pretoria, 2006. / Zoology and Entomology / unrestricted

Please read the Summary in the section 03chapter3 of this document / Dissertation (MSc)--University of Pretoria, 2005. / Plant Science / Unrestricted

Thesis (MSc)--Stellenbosch University, 2003. / Full text to be digitised and attached to bibliographic record. / ENGLISH ABSTRACT: The losses incurred to by the South African hardwood industry because of damage caused by the larvae of the Australian eucalyptus borers Phoracantha semipunctata (Fabricius) and P. recurva Newman (Coleoptera: Cerambycidae) were countered by the introduction of various biological control agents. Megalyra fasciipennis Westwood (Hymenoptera: Ichneumonidae), restricted to the southwestern Cape for nearly 91 years after its probable establishment in 1910, is a specialist pupal parasitoid achieving a parasitism level of up to 52.5 %. It has an activity peak in early spring, which coincides with the pupation of a large percentage of its hosts that had overwintered as larvae. The average length of the ovipositor of M. fasciipennis (42.71 ± 5.33 mm S.D.) was longer than the average tunnel length (31.34 ± 11.85 mm S.D.) to the pupal chamber of Phoracantha spp, within the log despite variations in the thicknesses of the eucalypt stems. Stem thickness therefore did not adversely affect the level of parasitism. Megalyra fasciipennis adults are diurnal, with activity largely determined by temperature. Over 70 % were active between 25°C and 34 °C, the minimum threshold for activity being 16°C. Optimum temperature for oviposition was 30 °C. Males became active before the females and maximum oviposition occurred between 10hOOand 15hOO. In 1993, a host specific egg parasitoid, Avetianella longoi Siscaro (Hymenoptera: Encyrtidae), was introduced for the control of Phoracantha spp. A total of 7791 A. longoi adults and 80 parasitised eggs were released around Cape Town between 1993 and 1995 before establishment was confirmed. Dispersal was monitored annually and was determined to occur at a rate of 50 km/year. By 1998 A. longoi had dispersed 300 km north of Cape Town to Lutzville and 270 km east to Riversdal. Subsequent to a satellite release in Knysna during 1994, it has been established 40 km from this release site, at Plettenberg Bay. The parasitoid has also bridged a LO km expanse of ocean to establish on Robben Island, immediately off the west coast of Cape Town. Avetianella longoi has a preference for the eggs of P. semipunctata, which is the most likely cause for the decline in the population of P. semipunctata. However, P. recurva remains relatively unaffected. Average parasitism of Phoracantha spp. eggs by A. longoi was 59.4 %. An undescribed Cleonymus sp. (Hymenoptera: Pteromalidae) of unknown origin (the genus being widely distributed on several continents), was discovered in the Cape Peninsula parasitising late instar larvae of P. semipunctata and P. recurva. This ectoparasitoid lays its eggs (mean number per larva = 20.3 ± 15.2 S.D.) through the bark into the host chamber after the host has been paralysed. The host is entirely consumed and pupation takes place in the chamber with wasps emerging in the ratio of 1 male: 3 females. Although uncommon in the field, mass rearing of these wasps in culture was easily accomplished and a consignment was released in the Tzaneen district in 1993, where it was confirmed to have become established in 1996. Bark thickness constraints on the effectiveness of this parasitoid as a biological control agent because it's short ovipositor restricts the wasp to certain eucalypt species or trees with thin bark. The introduction into South Africa in 1995 and attempted establishment of the larval parasitoids, Syngaster lepidus Brullé (Hymenoptera: Braconidae), Jarra phoracantha Marsh & Austin (Hymenoptera: Braconidae) and J maculipennis Marsh & Austin proved unsuccessful in the Western Cape. However, the former two species were established in the Tzaneen district and their recruitment for release in the Western Cape should be considered. The present guild of biological control agents has been insufficient to give the required control. In the absence of biological control agents, intraspecific competition amongst host larvae is the major mortality factor. Although high levels of mortality are achieved as a result of parasitism despite the biological constraints of the parasitoids (e.g. the narrow activity peak of A. longoi and the restriction of Cleonymus sp. to thin barked eucalypts), their combined parasitism has succeeded in reducing the competition between host larvae, resulting in fewer yet larger host beetles emerging. The introduction of additional viable agents to assist in the biocontrol of Phoracantha spp. is required. / AFRIKAANSE OPSOMMING: Die verliese wat die Suid-Afrikaanse hardehoutbedryf ly as gevolg van skade veroorsaak deur die bloekomboorders Phoracantha semipunctata en P. recurva (Coleoptera: Cerambycidae), is bekamp deur die invoer van verskeie biologiese beheeragente. Megalyra fasciipennis Westwood (Hymenoptera: Ichneumonidae), beperk tot die Suidwes-Kaap vir byna 91 jaar nadat dit waarskynlik in 1910 daar gevestig is, is In spesialis papieparasitoïd wat In parasitismevlak van tot 52.5% bereik. Dit het In aktiwiteitspiek in die vroeë lente wat saamval met die papievorming van baie gasheerlarwes wat oorwinter het. Die gemiddelde lengte van die eierboor van M. fasciipennis (42.71 ± 5.33 mm S.A.) was langer as die gemiddelde tonnellengte (31.34 ± 11.85 mm S.A.) na die papieholte van die gasheer binne in die hout, ten spyte van die variasie in die dikte van die bloekomstamme. Stamdikte het dus nie In nadelige uitwerking op die vlak van parasitisme nie. Volwassenes van M.fasciipennis is bedags aktief en aktiwiteit word hoofsaaklik deur temperatuur bepaal. Meer as 70% was tussen 25°C en 34 °C aktief, met 16°C as die minimum drumpel vir aktiwiteit. Mannetjies het voor die wyfies aktief geword en maksimum eierlegging het tussen 10hOOen 15hOO plaasgevind. In 1993 is die gasheerspesifieke eierparasitoïd Avetianella longoi Siscaro (Hymenoptera: Encyrtidae) vir die beheer van Phoracantha spp. ingevoer. Van 1993 tot 1995 is 7791 volwassenes van A. longoi en 80 geparasiteerde eiers rondom Kaapstad vrygelaat en dis vasgestel dat die spesies gevestig het. Die verspreiding daarvan is jaarliks gemonitor en dis vasgestel dat dit teen 50 km per jaar plaasvind. Teen 1998 het dit versprei tot 300km noord van Kaapstad na Lutzville en 270 km oos na Riversdal. Na 'n satelliet-loslating by Knysna in 1994 het dit 40 km verder by Plettenbergbaai gevestig. Die parasitoïd het ook 10 km van die oseaan oorgesteek om op Robbeneiland, wes van Kaapstad te vestig. Avetianella longoi gee voorkeur aan die eiers van P. semipunctata en dis waarskynlik die rede vir die afname in die getalle van hierdie spesies, maar P.recurva word relatief min beïnvloed. Die gemiddelde graad van parasitisme van Phoracantha spp. was 59.4%. Dit is gevind dat 'n onbeskryfde Cleonymus sp. (Hymenoptera: Pteromalidae) van onbekende oorsprong (die genus kom wyd verspreid in verskeie vastelande voor) die laat instar larwes van P. semipunctata en P. recurva parasiteer. Hierdie ektoparasitoïd lê sy eiers (gemiddeld 20.3 ± 15.2 S.A.) in die gasheerholte nadat die gasheer eers verlam is. Die gasheer word heeltemalopgevreet en pupering vind plaas in die holte plaas. Volwassenes kom uit in verhoudingvan drie mannetjies tot een wyfie. Alhoewel skaars in die natuur, kan hierdie wesp maklik in massa geteel word. 'n Besending is in die Tzaneen distrik vrygestel en in 1996 is vasgestel dat hulle gevestig het. Basdikte is 'n beperkende faktor in die gebruik van hierdie parasitoïd as effektiewe beheeragent vir biologiese beheer omdat die kort lengte van die eierboor die wesp sal beperk tot bloekomsoorte met dun bas. Die invoer na Suid-Afrika in 1995 en vestiging van die larwale parasitoïde Syngaster lepidus Brullé (Hymenoptera: Braconidae), J. phoracantha Marsh & Austin (Hymenoptera: Braconidae) en J. maculipennis Marsh & Austin was onsuksesvol in dieWes-Kaap. Die twee spesies is egter in die distrik Tzaneen gevestig en versameling met die oog op loslating in die Wes-Kaap behoort oorweeg te word. Die huidige gilde van biologiese beheer-agente is onvoldoende om die vereiste graad van beheer te verskaf. In die afwesigheid van biologiese beheer-agente is intraspesifieke kompetisie tussen gasheerlarwes die belangrikste mortaliteitfaktor. Alhoewel hoë vlakke van mortaliteit as gevolg van parasitisme bereik word, ten spyte van die biologiese beperkings van die parasitoïde (bv. die kort aktiwiteitspiek van A. longoi en die beperking van Cleonymus tot bloekoms met dun bas), het die gekombineerde parasitisme daarin geslaag om die kompetisie tussen gasheerlarwes te verlaag, met die gevolg dat minder maar groter gasheerkewers verskyn het. Dit is dus nodig dat addisionele organismes gevestig word om by te dra tot die biologiese beheer van Phoracantha spp.

Studies presented in this dissertation highlight the importance of fungal pathogens in forestry nurseries in South Africa. Both Acacia meamsii seedlings and Eucalyptus hybrid cuttings are shown to be affected by important nursery pathogens. Chapter one presents an evaluation of the potential importance of pathogens to Eucalyptus hedge plants maintained in hydroponics. Hydroponics is a new technology being used in South African forest nurseries, which allows for the rapid establishment of Eucalyptus hedge plants. However, no information is available on pathogens affecting Eucalyptus in hydroponics. By applying information on pathogens of other hydroponic crops, several potentially important pathogens were identified and these reside in the genera Phytophthora, Pythium and Fusarium. Possible disease symptoms in Eucalyptus caused by these pathogens include wilting, stem cankers and root rots. Implementation of appropriate control measures that include cultural, biological and chemical practices could prevent and/or reduce disease impact in hydroponics. Chapter two presents the results of a survey of the roots of Eucalyptus hedge plants grown in an ebb and flow hydroponic system. An interesting result of the survey was the discovery of Cylindrocladium pauciramosum in the hydroponic system. This is the first report of the pathogen in a hydroponic system. Other important pathogens in the genera Phytophthora and Pythium were also isolated. Two Pythium species, namely P. dissotocum and P. helicoids, found in the roots and nutrient solution are new to Eucalyptus. Several Fusarium species were also isolated of which two, namely F. nygamai and F. lateritium, are also new to Eucalyptus. Chapter three of this dissertation presents the results of a survey of Eucalyptus cuttings conducted at four forestry nurseries in KwaZulu-Natal, South Africa. Several well-known Eucalyptus nursery pathogens were isolated. Cylindrocladium pauciramosum was identified as the dominant pathogen on Eucalyptus cuttings. This was confirmed based on morphological characteristics and DNA sequence comparisons. Pathogenicity tests conducted using a spore suspension of C. pauciramosum indicated that this pathogen is capable of infecting most commercial Eucalyptus clones used in South Africa. Chapter four considers a serious disease of Acacia mearnsii seedlings caused by an unidentified species of Cylindrocladium. Cylindrocladium pauciramosum was isolated from A. mearnsii seedlings showing girdling and stem canker symptoms. The pathogen was identified based on morphological characteristics and DNA sequence comparisons. Pathogenicity tests with Acacia seedlings confirmed the susceptibility of this tree to C. pauciramosum infection. This dissertation clearly indicates that Cylindrocladium pauciramosum is an important nursery pathogen in South African forestry nurseries. This pathogen has already been shown to be limiting during production of planting stock. I hope to have highlighted the importance of C. pauciramosum and other nursery pathogens in forestry nurseries in South Africa. This study will also hopefully provide information to forestry nursery managers and help them improve production. / Dissertation (MSc)--University of Pretoria, 2004. / Microbiology and Plant Pathology / Unrestricted

Thaumastocoris peregrinus (T. peregrinus) is a sap-sucking insect that feeds on Eucalyptus leaves. It poses a major threat to the forest sector by reducing the photosynthetic ability of the tree, resulting in stunted growth and even death of severely infested trees. The foliage of the tree infested with T. peregrinus turns into a deep red-brown colour starting at the northern side of the canopy but progressively spreads to the entire canopy. The monitoring of T. peregrinus and the effect it has on plantation health is essential to ensure productivity and future sustainability of forest yields. Insitu hyperspectral remote sensing combined with greater availability and lower cost of new generation multispectral satellite data, provides opportunities to detect and map T. peregrinus damage in plantation forests. This research advocates the development of remote sensing techniques to accurately detect and map T. peregrinus damage, an assessment that is critically needed to monitor plantation health in South Africa. The study first provides an overview of how improvements in multispectral and hyperspectral technology can be used to detect and map T. peregrinus damage, based on the previous work done on the remote sensing of forest pests. Secondly, the utility of field hyperspectral remote sensing in predicting T. peregrinus damage was tested. High resolution field spectral data that was resampled to the Hyperion sensor successfully predicted T. peregrinus damage with high accuracies using narrowband normalized indices and vegetation indices. Field spectroscopy was further tested in predicting water stress induced by T. peregrinus infestation, in order to identify early physiological stages of damage. A neural network algorithm successfully predicted plant water content and equivalent water thickness in T. peregrinus infested plantations. The result is promising for forest health monitoring programmes in detecting previsual physiological stages of damage. The analysis was then upscaled from field hyperspectral sensing to spaceborne sensing using the new generation WorldView-2 multispectral sensor, which contains key vegetation wavelengths. Partial least squares regression models were developed from the WorldView-2 bands and indices and significant predictors were identified by variable importance scores. The red edge and near-infrared bands of the WorldView-2 sensor, together with pigment specific indices predicted and mapped T. peregrinus damage with high accuracies. The study further combined environmental variables and vegetation indices calculated from the WorldView-2 imagery to improve the prediction and mapping of T. peregrinus damage using a multiple stepwise regression approach. The regression model selected the near infrared band 8 of the WorldView-2 sensor and the temperature dataset to predict and map T. peregrinus damage with high accuracies on an independent test dataset. This research contributes to the field of knowledge by developing innovative remote sensing techniques that can accurately detect and map T. peregrinus damage using the new generation WorldView-2 sensor. The result is significant for forest health monitoring and highlights the importance of improved sensors which contain key vegetation wavelengths for plantation health assessments. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.