Tesi sul tema "Pine Diseases and pests South Australia"

Bibliography: leaves 81-100. Entry of inoculum into a crop and disease development in the crop cannot be prevented because spores are airborne and there is a lack of highly resistant varieties. This makes complete control of chocolate spot unlikely. It should however, be possible to improve current levels of disease control through the integration of the factors identified in the study.

Three pages of addenda pasted inside back cover. Bibliography: leaves 166-189. Rhizoctonia solani is a complex species comprising morphologically basidiomycetous imperfect fungi. This study aimed to determine genetic diversity within R. solani AG-3 causing rhizoctonia disease of potato in South Australia. For this purpose, pectic zymogram, PCR, DNA fingerprinting and RFLP techniques were used in conjunction with traditional plant pathology procedures.

Bibliography: leaves 224-236. The study aimed to determine the distribution of both P. thornei and P. neglectus in South Australia. Also to study the field and laboratory population dynamics of P. thornei in relation to wheat yields, to determine its host range on a variety of cereal and non-leguminous hosts and to identify possible sources of nematode resistant wheat cultivars/varieties. Preliminary experiments studied the involvement of root rotting fungi with the nematode in wheat disease.

Bibliography: leaves 307-329. This study concludes that in soils in South Australia where root-rotting fungi and P. neglectus exist together, root disease of wheat is caused by their combined effect. Evidence suggests that P. neglectus not only contributes to this interaction through mechanical wounding of roots, but also causes biochemical and physiological changes in plants, making them more prone to fungal infection.

Bibliography: leaves 131-153. This thesis investigates the mechanisms of manganese (Mn) efficiency (genetic tolerance to Mn-deficient soils) in barley (Hordeum vulgare L.) at both physiological and molecular levels.

Includes bibliographical references (leaves 102-114) The highly successful biological control of the citrophilous mealybug Pseudococcus calceolarie (Maskell) (CM) by the parasitic wasp Coccophagus gurneyi Compere in several countries led to the release of this parasitoid in the Riverland of South Australia as part of an integrated pest management program. However CM has not been successfully controlled in this region. The results of this study may help to explain the lack of effective biological control of CM in Riverland citrus.

Bibliography: p. 410-429.
429 p., [20] leaves of plates : ill. (some col.), map ; 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 Plant Science, 1995?

Title page, table of contents and abstract only. The complete thesis in print form is available from the University of Adelaide Library.
Grapevine powdery mildew, caused by the fungus Uncinula necator Schweinitz Burrill, is a major disease affecting grape yield and quality worldwide. In conventional vineyards, the disease is controlled mainly by regular applications of sulphur and synthetic fungicides, such as demethylation inhibiting fungicides (DMIs), and in organic agriculture by sulphur and canola-based oils. The impending restrictions on the use of sulphur in organic viticulture, the development of resistance to DMls in Australia and elsewhere, and the demand for residue-free grapes create a need for effective alternatives to sulphur and synthetic chemicals. This research has identified potential replacements for synthetic fungicides and sulphur in the control of powdery mildew, such as milk, whey, bicarbonates and canola oil-based sprays. A series of greenhouse experiments was conducted to evaluate 34 potential novel materials and biological agents for efficacy in controlling powdery mildew. The most effective treatments applied were Bacillus subtilis (which reduced disease by 94% compared to the untreated control), Synertrol Horti-Oil® (a canola oil-based product, 92%), milk (70%), whey (64%) and Ecocarb® (potassium bicarbonate, 58%). Milk and whey provided increased control of powdery mildew as the concentration increased. The efficacy of milk tended to decrease as the fat content of the milk was reduced. The materials that were most promising in the greenhouse were then assessed in field trials in commercial vineyards. Applications of milk, whey and mixtures of a canola oil-based product and potassium bicarbonate, applied at rates of 300 L/ha to 1000 L/ha depending on canopy development, reduced the severity of powdery mildew. The severity of powdery mildew on vines sprayed with a 1:10 dilution of milk, 45 g/L whey powder and mixed programs was not significantly different from that on vines sprayed with sulphur (wettable powder, 3 g/L). However, the relative control of powdery mildew by the test materials in field trials was highly dependent on the degree of coverage of the plant surface achieved. In vineyards where coverage was compromised, the degree of control of powdery mildew was reduced, often to commercially unacceptable levels. Electron spin resonance (ESR) and scanning electron microscopy (SEM) were used to investigate the possible mode or modes of action of milk and whey in the control of powdery mildew. The ESR experiments showed that production of oxygen radicals by various components of milk in natural light was associated with reduced severity of powdery mildew. SEM images showed that milk and whey caused the hyphae of U necator to collapse and damaged conidia within 24 h of treatment. Hydrogen peroxide, applied as a source of free radicals, also caused collapse of the hyphae of U necator within 24 h but did not damage conidia, and appeared to stimulate germination. Lactoferrin (an antimicrobial component of milk) ruptured conidia, but damage to hyphae was not evident in lactoferrin-treated samples until 48 h after treatment. The results suggested that fats, free radical production along with the action of lactoferrin, and possibly other proteins, are associated with the control of powdery mildew by milk. Novel soft fungicides, such as milk and oil plus bicarbonate mixtures, were effective alternatives to sulphur and synthetic fungicides in certain South Australian conditions. Biological agents (including B. subtilis, which was highly effective in greenhouse experiments) did not provide acceptable control of powdery mildew in the vineyard.
http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1116612
Thesis (Ph.D.) -- University of Adelaide, School of Agriculture and Wine, 2004

Bibliography: leaves 221-240.
viii, 240, [13] leaves : ill. (some col.), maps ; 30 cm.
Title page, contents and abstract only. The complete thesis in print form is available from the University Library.
This thesis deals with the introduction of "Aphidius rosae" as a classical biological control agent into South-Eastern Australia. Appropriate host specificity tests are carried out. Laboratory experiments are also completed to gain a better understanding of the interactions between host and parasitoid in the field. The study aims to monitor the performance of the control agent in the Adelaide environment for the first two years after initial release. It is also planned to invent an experimental field technique to estimate the impact of the control agent on rose aphid populations.
Thesis (Ph.D.)--University of Adelaide, Dept. of Crop Protection, 1997

Bibliography: leaves 221-240. This thesis deals with the introduction of "Aphidius rosae" as a classical biological control agent into South-Eastern Australia. Appropriate host specificity tests are carried out. Laboratory experiments are also completed to gain a better understanding of the interactions between host and parasitoid in the field. The study aims to monitor the performance of the control agent in the Adelaide environment for the first two years after initial release. It is also planned to invent an experimental field technique to estimate the impact of the control agent on rose aphid populations.

Bibliography: leaves 82-89. This study is aimed at providing information on control measures against Gaeumannomyces graminis var. tritici (abbreviated to Ggt) in annual pastures across southern Australia. The impact of timing of herbicide application, the impact of variation in timing of rainfall patterns, as well as herbicide application on the control of Ggt are also discussed. Additional experiments examine the ability of grass genera to host and carry over Ggt.

Fusarium circinatum is a fungal pathogen that has had a serious impact on pine production throughout the world. It attacks most Pinus species including Pinus elliottii, Pinus patula and Pinus radiata. Infections in South Africa (SA) are largely on seedlings, and result in fatal seedling wilt. Accurate and quick detection systems suitable for field use are needed to monitor the spread of the disease and optimize fungicide applications. Detection of F. circinatum is currently based on visual observations of typical symptoms. However, symptoms are not unique to the pathogen and can be caused by other biotic and abiotic stress factors. Nucleic acid-based identification techniques using PCR are available for different fungal species. These are sensitive and accurate, but they are expensive and require skilled biotechnologists to conduct the assays. In this study an enzyme-linked immunosorbent assay (ELISA) was developed to identify F. circinatum in infected seedlings. This optimized ELISA is able to discriminate between F. circinatum and two other fungi that frequently affect pine. This method has advantages over other assays because of its ease of operation and sample preparation, sensitivity and the ability to run multiple tests simultaneously. Mycelium-soluble antigens from Diplodia pinea (=Sphaeropsis sapinea), F. circinatum and F. oxysporum were prepared in nutrient broth. Analysis of these antigens on SDS-PAGE indicated the presence of common antigens between the different fungal pathogens. Some antigens were expressed more by some isolates than by others. Separate groups of chickens were immunised with mycelium-soluble antigens from D. pinea, F. circinatum and F. oxysporum and exo-antigen from F. circinatum prepared in nutrient broth. A 34 kDa protein purified from SDS-PAGE specific for D. pinea was also used for immunisation. Five sets of antibodies were obtained including anti-D. pinea, anti-F. circinatum, anti-F. oxysporum, anti-F. circinatumexo and anti-D. pinea 34 kDa antibodies, respectively. Reactivity of these antibodies was evaluated against antigens prepared in nutrient broth using western blotting and ELISA. Western blot analysis indicated that immuno-dominant antigens for F. circinatum were larger than 34 kDa and their reactivity was not the same between different isolates. Each of the antibodies prepared using mycelium-soluble antigens showed increased reactivity when detecting its own specific pathogen, but cross-reactivity was observed. Anti-D.pineaantibodies showed minimal cross-reactivity with antigens from F. circinatum and F. oxysporum. Anti-F. circinatum antibodies cross-reacted with antigens from F. oxysporum but showed little cross-reactivity with D. pinea antigens. Anti-F. oxysporum antibodies showed more cross-reactivity towards antigens from F. circinatum than those from D. pinea. No reactivity was observed when anti-F. circinatum-exo antigen and anti-D. pinea 34 kDa antibodies were used in immuno-blotting analysis. Evaluation of antibody reactivity using indirect ELISA showed patterns similar to those observed on western blotting, where anti-D. pinea, anti-F. circinatum and anti-F. oxysporum antibodies showed the same cross-reactivity relationships. Anti-F. circinatum and anti-F. oxysporumantibodies showed a significant difference when reacting with antigens isolated from other pathogens including D. pinea, F. circinatum, F. oxysporum, F. solani, F. graminearum and F. culmorum (P = 0.001). No significant difference was observed when the antigens were detected with anti-D. pinea antibodies. Reactivity of anti-F. circinatum-exo and anti-D. pinea34 kDa antibodies was mostly similar to that of non-immune antibodies and showed no significant difference between detection of different antigens. Pine seedlings were artificially infected with the three fungal pathogens using a spore concentration of 1 – 1 x 106conidiaml-1.Infection was monitored using scanning electron microscopy. Results showed increased levels of mycelium growth on the stem and roots of the F. circinatum and F. oxysporum infected seedlings and on the leaves and stem in the case of D. pinea infected seedlings. These plant parts were used in ELISA tests for the detection of antigens. Isolation of antigens from the plant materials involved crushing plant parts in buffer and centrifugation of the suspension. The supernatant obtained was directly used in the assay. ELISA tests prepared in this study were sensitive enough to detect infection caused by 1 conidium ml-1at two weeks post inoculation. A positive reaction for detection of F. circinatum and F. oxysporum was indicated by an ELISA reading above an optical density at 405 nm. The plant material used in ELISA tests were further analysed using PCR. Results indicated that there was no cross-infection between seedlings and served as a confirmation of the disease-causing pathogen. This indicated that cross-reactivity observed was due to other factors such as common epitopes on the major antigens. Use of an ELISA dip-stick or ELISA using these antibodies should provide an easy, fast field test to identify infections of pine, discriminating between F. circinatum, F. oxysporum and D. pinea.
M.Sc.Agric. University of KwaZulu-Natal, Pietermaritzburg 2013.

Microxeromagna armillata ( Lowe, 1852 ) is a snail introduced snail to Australia which has established populations in the Riverland and Sunraysia citrus growing regions. Citrus exported from these regions to the USA has been rejected due to contamination with M. armillata, causing significant economic losses. The life history, phenology and activity of Microxeromagna armillata has not been studied in Australia : this forms the basis of this thesis. Microxeromagna armillata employs an iteroparous egg laying strategy in semi - field conditions and lays approximately 500 eggs per year. Field populations can reach high densities ( ∼ 4000 snails / m ² ), particularly during the winter months when juvenile recruitment occurs. Snails reach sexual maturity at ∼ 6mm in shell diameter and can grow to this size from a juvenile stage ( 2mm ) within six weeks. Microxeromagna armillata can reproduce successfully by self-fertilisation, and juveniles are able to aestivate with little reduction in subsequent fecundity. These traits make control of this pest a significant challenge. Leaf litter is the preferred habitat of M. armillata, but snails do move in the tree canopy. Cues for snail activity in the leaf litter and canopy appear to differ, as does the size of active snails in these areas. Microxeromagna armillata activity was low in the tree canopy during harvest compared to post harvest, intimating that fruit contamination is either occurring infrequently or post - harvest. Copper trunk bands were shown to minimise snail movement into the canopy and may be an important preventative measure. These findings have changed the recommendations for M. armillata management in citrus groves of south eastern Australia.
Thesis (Ph.D.)--School of Agriculture, Food and Wine, 2007.

Bibliography: leaves 140-158
ix, 158 leaves, [23] leaves of plates : ill., 1 map ; 30 cm.
Title page, contents and abstract only. The complete thesis in print form is available from the University Library.
Thesis (Ph.D.1985) Dept. of Plant Pathology, University of Adelaide

Attempts were made to grow Fergusobia nematodes in a dual aseptic culture with Eucalyptus camaldulensis. Callus tissue was grown from E. camaldulensis stem pieces in aseptic conditions. Calli were prone to deterioration after 14 days unless transferred to fresh growth medium. Lower levels of solutes (25% Murashige and Skoog salts, 25% plant vitamins and 0.5% sucrose) were more successful than published concentrations. Fergusobia J2 nematodes were surface sterilised with either Hibitane or washed with water to prepare them for inoculation of callus (Hay, 1994). Fergusobia subsequently recovered from plates of callus were all dead, which raised questions of how the nematodes are suited to Murashige and Skoog salt solutions. The survival of Fergusobia in aqueous solutions was then observed. It has been assumed that Fergusobia live about 2 days after dissection. Amphimictic nematodes from E. camaldulensis axial bud galls were used for a survival study. Nematodes lived for as long as 12 days in fresh tap water and 11 days in 1% M.S. solution. They were more active in tap water than in 1% M.S. solution. Nematodes in a dish together with dissected gall material died within 2 days. Nematodes in a separate dish with fresh tap water and clean gall fibres were observed to gather around the fibres. Observations of Fergusobia could be made within fresh solutions providing deteriorating gall tissues were removed from the dish. Gall production was attempted on E. camaldulensis grown in the glasshouse. These tree saplings were pruned to encourage new growth and periodically treated for infestations of scale insects leading to growth of sooty mould. Two forms of cage construction were used: (1) 1 m ³ screened cages and (2) acetate sleeves as used by Goolsby et al., 2000. Within the 1 m ³ cages containing flies, the growing points on saplings were blackened, possibly due to over-exploitation by ovipositing flies. One growing point caged in an acetate sleeve showed oviposition scars but did not produce a mature gall. Production of galls in the glasshouse was hindered by a lack in coincidence of flies emerging from mature galls and the flush of new growth following pruning. The production of galls within the glasshouse was not achieved. The phenology of E. camaldulensis, a host for the Fergusonina/Fergusobia mutualism, and gall ecology were observed in a two-year, non-destructive, field study in the Urrbrae Wetlands, Adelaide, South Australia. Tree growth and gall development was observed in the lower regions (0 – 2 m) of young trees. Three bud forms, terminal leaf bud, axial leaf bud and flower bud galls were monitored on the trees. The densities of galls were highly seasonal. Greatest density of growing points, axial leaf bud and flower bud galls occurred mostly during mid-winter to spring, whereas that of terminal leaf bud galls occurred during mid-spring to summer. Galling of flower buds did not appear to influence flowering and more flower buds and flowers occurred in the second year of the study as the trees matured. Trees mostly had medium (30-70%) levels of leaf damage, but there were seasonal trends in damage levels. Low scores for leaf damage were associated with increases in flower bud and flower production. Leaf damage, including sooty mould, appeared to increase during the cooler winter months. There were no significant seasonal relationships between levels of leaf damage and either growing point density or the occurrence of galls. When trees were compared with each other, those with lower leaf damage were more likely to have more growing points. The appearance of the canopy and the likelihood of a tree to have galls varied greatly between the trees. One tree was particularly susceptible to leaf attack, rarely had new leaves and produced no mature galls during the study. The colouring of leaves varied between trees, which indicates possible genetic variations causing some trees to be more likely hosts for Fergusonina/Fergusobia. Both new vegetative growth and terminal leaf bud galls were concentrated on the northern and eastern quadrants. Axial leaf bud and flower bud galls occurred more on the western or southern quadrants where they were possibly more protected from sun exposure on the northern or eastern quadrants. Axial galls on the northern side of one tree became reddened while those in the southern and western quadrants remained green. Reddening of axial galls may increase their likelihood of parasitism and predation by birds. Each of the three gall forms occurred within certain positions in the canopy. The tree host resource is partitioned effectively, with the three gall forms occurring on three different host structures. Additionally, the two vegetative forms terminal leaf bud and axial leaf bud galls occur on different shoot regions and in different seasons. The numbers of the galls is probably also affected by biotic and climatic influences. Parasitism, plant canopy shading, nutrient levels and host genetics are possible influences. Assuming an interval of 4 weeks between oviposition and first observation within the current study, terminal leaf bud galls had an average longevity of 11 weeks and axial leaf bud galls an average longevity of 14 weeks. Flower bud galls had longevities of 14 to 27 weeks from oviposition to senescence, assuming an interval of 6 weeks between oviposition and first observation within the current study. Flowers and flower buds occur irregularly within the eucalypts so it would be advantageous for flies and nematodes developing within flower bud galls to have extended or variable longevities to allow fly emergences to coincide with new flower buds. Not all of the galls recorded matured to produce adult flies. Nearly half of the terminal leaf bud galls initiated were aborted, recorded as absent, parasitised or eaten (45% of initiated galls). Of the three gall forms, they were the most prone to obvious parasitism and as many as 12 hymenopteran species have been reared from terminal leaf bud galls on E. camaldulensis (Taylor et al., 1996). These galls obviously provide a resource for many species within multiple trophic levels. Fourteen percent of axial leaf bud galls were absent or eaten and birds were seen breaking off and feeding on the galls. More than half (55%) of the initiated flower bud galls disappeared during the period of observation, possibly due to the foraging of birds. Destructive sampling and rearing out of parasitoids from both axial leaf bud and flower bud gall forms is needed to establish what species exist within them. Terminal leaf bud galls ranged from 7.5 to 30.1 mm in diameter and 10.0 to 43.6 mm in length. Flower bud gall size varied, with the largest being 15.0 mm by 22.3 mm. Axial leaf bud galls, ranged from 2.6 to 13.0 mm in diameter and length ranged from 2.3 to 10.5 mm. The larger axial leaf bud galls were nodular and appeared to have multiple locules. Destructive sampling and rearing out of flies is needed to establish the relationship between size and numbers of flies emerging. Terminal leaf bud galls increased in size, including many locules and exit holes per gall. Axial leaf bud galls were much smaller than the terminal leaf bud galls and 99% had only one to three exit holes. The rounded shape and presence of few locules within the axial leaf bud galls indicate that this form is limited to a shape and size producing few flies. The observation of greater size of terminal leaf bud galls suggests that these galls may have multiple foundresses. Twelve of the 13 flower bud galls with exit holes had either one or two holes. In flower bud galls on E. camaldulensis. the operculum remains sealed and the characteristic Fergusonina “window” appears at the side of the flower bud before fly emergence through a single hole. Destructive sampling is also necessary to determine parasitism of each of the gall forms.
http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1331016
Thesis (M.Sc.) -- University of Adelaide, School of Agriculture, Food and Wine, 2008

Errata and addenda attached. Bibliography: leaves 195-211. This thesis is concerned with the biology of Eriosoma lanigerum (WAA) and its parasitoid (Aphelinus mali), the impact of the pest on the crop and the effects of pesticides used routinely in South Australian orchards on both woolly apple aphid and the parasitic wasp. The study identifies current management practices of apple growers in South Australia. Aspects of the biology of WAA and A.mali are examined. Work is also done on the toxicity against WAA and A.mali of insecticides used in the control of codling moth and phytophagous mites. The effects of WAA infestation on the growth of young trees are investigated. The seasonal activity of WAA on mature trees is determined over a two season period.

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

Summary: The future mass propagation of elite families of Pinus patula by cuttings is a realistic method of deployment if the short-term performance of cuttings and seedlings are confirmed at harvesting. This will impact significantly on the future outlook of forestry in South Africa as softwood yields are improved substantially through the introduction of material of high genetic value in commercial plantings. This, however, will require significant changes in future silviculture and other management practices as foresters and plantation staff learn to regenerate, maintain, and schedule the harvesting of cutting stands according to a different set of demands as a result of the change in plant type. Contrary to operational experience, cutting survival was similar to seedling survival in all field studies. This indicates that factors other than those that were studied and reported on, such as planting techniques, may be contributing to mortality. Also, due to the different root structure of cuttings they may be more fragile. The similar survival observed in these trials, therefore, may have been due to the close supervision given to the planting operations by the research staff. Although survival was similar, both plant types survived unacceptably poorly in the majority of studies with an average stocking of approximately 50% at one year. It is therefore anticipated that commercial stands will require several blanking operations in order to achieve an acceptable stocking in excess of 85% by the following planting season. The reduction in expected profitability as a result of blanking costs, delayed establishment, and the loss of improved genetic plant material, indicates that this is an area that still requires further research irrespective of what plant type is being planted. The pathogen, Fusarium circinatum, was commonly isolated from the planting stock before and after planting in two studies. Due to its virulent nature, it was assumed that mortality on the trees on which F. circinatum was isolated was principally due to this pathogen. At planting all plants were observed to be healthy and free of disease indicating that this pathogen maybe carried from the nursery to the field in a cryptic form, either inside or outside the plant tissue , which results in the death of the newly planted tree. In two field studies, where F. circinatum was commonly isolated, the application of Benomyl fungicide and to some extent the biological control agent Trichoderma harzianum at planting appeared to improve survival although this improvement was not significant. Laboratory studies, designed to determine alternatives to Benomyl fungicide, indicated that three fungicides (Octave, Folicur and Tilt), three sterilants (Sporekill®, Prasin®and Citex®) , as well as a biological control agent (T.harzianum), were all highly successful in controlling F. circinatum colony growth in vitro. It is recommended that these products undergo nursery testing , where the plant material is inoculated with F. circinatum spores, in order to test their efficacy and possible phytotoxicity in vivo before commercial application. Post-planting survival was also affected by site climate . Greater temperature extremes, as well as lower humidity and less rainfall resulted in poor survival. Plant dimension at planting was found to interact with site quality where it was a significant factor on a poor quality site. Optimal cutting dimensions at planting was a root collar diameter of 2.8 - 3.2 mm, and a stem height greater than 7 cm at planting for cuttings produced in cavities 90 ml in volume. Optimal seedling dimensions at planting were a root collar diameter of 1.8 - 2 mm, and a stem height of 10 - 15 cm for seedlings produced in cavities 80 ml in volume. In a separate study, plant morphological criteria influenced medium-term growth, where greater root mass and thicker cutting root collar diameters at planting improved field growth performance for seven years after planting. A greater root mass at planting was achieved by raising cuttings in containers that could support greater medium volume. From the study it was concluded that cuttings should be raised for an approximate period of 9 months in container cavities no smaller than 80 ml in volume and possess an oven-dry root mass of 0.3 - 0.5 g at planting. In addition to similar survival, the cuttings in this study grew either similarly to, or in some cases out-performed, the seedlings that were used as a control. Several other published studies indicate that hedge maturation poses the greatest threat to the success of softwood cutting deployment. This is especially true in clonal forestry and methods to maintain juvenility, such as cold storage of shoots and cryopreservation, require further research before clonal plantations of P. patula can be realised. In the studies carried out on family hedges in this report, the effect of donor hedge maturation was found to influence nursery management practice and the characteristics of rooted cuttings. The nursery data indicates that rooting efficiency, root system quality, and stem size and form, all decline with increasing hedge age particularly from two years after the date of sowing. A decline in root system quality was particularly apparent and was observed prior to a decline in rooting efficiency. If field trials indicate poorer performance from older hedges , it may be necessary to determine whether the causes are purely ontogenetic, morphological, or both before drawing final conclusions about hedge longevity. Until such results are known, it is recommended that P. patula cuttings should be propagated from seedling donors maintained as hedges , approximately 15 cm high, for a period not more than three years from the date of sowing.
Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.

"August 2003."
Includes bibliographical references (leaves 294-333)
2 v. (xxxi, 333 leaves) ; 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, School of Agriculture and Wine, Discipline of Plant and Pest Science, 2005

There is currently little knowledge about the dynamics of invertebrates in Australian viticultural ecosystems. This study was conducted in Coonawarra vineyards over three seasons (years) and has focused on identifying natural enemies, their seasonal phenology, multiple species interactions, and potential for the suppression of the pest lepidopteran Epiphyas postvittana (Tortricidae). The work presented in this thesis shows that endemic natural enemies have far greater potential to control E. postvittana than has been realised. An initial survey identified a diverse and abundant range of potential natural enemies. Of these, the species most likely to attack E. postvittana include a predatory mite Anystis baccarum and a number of hymenopteran parasitoids. The most abundant parasitoid in the vineyards was a braconid, Dolichogenidea tasmanica. Understanding the characteristic behaviour of parasitoids in response to host density can help to gauge their potential for pest suppression. The results of large-scale field experiments showed that the response of D. tasmanica to the density of E. postvittana was inversely density-dependent, and that parasitism was consistently higher in Cabernet Sauvignon compared with Chardonnay varieties. Despite the fact that interactions among multiple species of natural enemies can increase or decrease pest suppression, particularly when they share a common prey/host, few multispecies interactions have been investigated. Laboratory studies identified a novel interaction between the predatory mite A. baccarum an abundant predator in the vine canopy, the parasitoid D. tasmanica and host E. postvittana larvae. Although A. baccarum readily ate E. postvittana eggs and free roaming larvae, they could not access larva in their silk leaf rolls. However, the addition of D. tasmanica significantly increased predation of E. postvittana larvae, by altering the behaviour of host larvae and increasing their vulnerability to the mite. Experiments conducted at a landscape level in the Coonawarra showed that D. tasmanica was also present in habitat other than vineyards including native vegetation. However, it was not present in highly disturbed habitats. Although the exact mechanism for this remains unknown, results indicate that viticultural practices and resources in the surrounding landscape can influence the presence of parasitoids. Together, the findings presented in this thesis make a significant contribution towards developing sustainable pest management in Australian viticulture.
http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1320930
Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2008

Bibliography: leaves 141-145
vii, 145 leaves, [4] leaves of plates : ill. (4 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, Depts. of Plant Pathology and Agronomy, 1986

After European settlement, Australian rangelands especially in South Australia underwent significant changes because of the main land use of pastoralism. Many studies have revealed that the plant communities are negatively effected by herbivory mainly by sheep. The main aim of this study is to separate the different effects of sheep, rabbits and kangaroos. This was examined by survey supported by experimental and modelling research. A 32,000 km² area previously surveyed by Tiver and Andrew (1997) in eastern South Australia was re-surveyed to monitor populations of perennial plant species at sites of various intensity of grazing by sheep, rabbits and kangaroos (goats populations are low in the study area), the most important vertebrate herbivores. Plant population data were collected in both sheep paddocks and historically ungrazed by sheep (road reserves) by using the Random Walk method and analyzed using Generalized Linear Modelling (GLM) to separate the effects of sheep and rabbits on plant regeneration and their regeneration in response to grazing. These data were also compared to similar data collected by Tiver and Andrew in 1992 (1997) to ascertain if the reduction in rabbit numbers through introduction of RCV had allowed increased regeneration. Regeneration of many species inside paddocks were negatively affected and species in roadside reserves neither did not significantly increase from 1992 to 2004. However, some species showed increase of populations in spite of sheep grazing, with some species being less susceptible than others. This research also indicates kangaroo grazing impact on some plant species. Reduction in rabbit numbers following the 1995 release of calicivirus has not been effective in restoring regeneration. Another experiment was conducted at Middleback Field Station near Whyalla to identify herbivore grazing pressure on the arid zone plant species Acacia aneura using unfenced, sheep fenced and rabbit fenced grazing exclosures. This experiment was set up with seedlings in exclosures, ten replicates of each treatment, at plots four different distances from the watering point to identify the survivorship of seedlings. Data were collected by recording canopy volumes of seedling over an 18 month period and analyzed by Residual Maximal Likelihood (REML). Seedlings both near and far from the watering point were severely effected by large herbivores, either sheep, kangaroos or both, and in a separate experiment kangaroo grazing effects on the seedling were also identified. Seedlings browsed by the rabbits were recovered better than the seedlings grazed by the large herbivores. Decreasing kangaroo activities has been noticed when the rabbit movements increased. Computer modelling was conducted to predict the future plant population structure over 500 years using a matrix population model developed by Tiver et al. (2006) and using data collected in the survey as a starting point. Extinction probabilities of populations of Acacia aneura near watering points, far from watering points and under pulse grazing scenarios were compared. Sheep grazing was found to cause eventual extinction of populations in all parts of sheep paddocks. Together, the results indicate that sheep are the major herbivore suppressing regeneration of perennial plant species. Kangaroo and rabbits have an identifiable but lesser effect. The results have implications for conservation and pastoral management. To achieve ecological sustainability of arid lands a land-use system including a network of reserves ungrazed by sheep and with control of both rabbit and kangaroo numbers will be required.