Typewritten copy / 1 v. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Waite Agricultural Research Institute, 1955

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Typescript, etc.

Call number: LD2668 .T4 1979 T73 / Master of Science

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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.

The seasonal life history of the cereal stem moth (CSM), Ochsenheimeria vacculella Fischer von Roslerstamm, (Lepidoptera : Ochsenheimeriidae) was investigated in a commercial field of annual ryegrass in the Willamette Valley, OR from January 1993 to August 1994. Phenology of life stages, effect of temperature on eclosion, and development of larvae on potential hosts of economic importantce were also studied. First records of parasitization and effects of cultural practices on this potential pest in annual ryegrass were reported. CSM is a recent introduction to North America from a monobasic family of the Palearctic region. Its life cycle is functionally univoltine in commercial ryegrass seed fields. Eggs are characteristically deposited on interior wooden walls, ceilings and straw bales or piles in outbuildings from June through September. Eclosion occurs bimodally with approximately fifty percent of current season eggs hatching in late June and July. The remainder overwinter and hatch in February and March. Larvae ballooned from oviposition sites to potential hosts and were found in annual ryegrass from February to early June. First instar larvae typically mine leaves; later stadia are stem borers. Variance to mean ratios of larvae sampled in annual ryegrass described a clumped population. Pupation occurred from late May to early July. The pupa was enclosed in a flimsy cocoon usually located on the inside of a flag leaf's sheath. Shortly after emergence in early June and July, adults fly to outbuildings preferentially remaining within those where grass straw has been stored. Migration from the field and subsequent flight, copulation and oviposition within buildings occurred only on bright days from approximately noon to 4:30 pm (PDT) through September at which time most adults have died. Two species of larval parasitoids in the Eulophidae and Ichneumonidae were very abundant in the annual ryegrass field under study during June and July 1994. Their combined parasitization rate of CSM larvae exceeded ninety percent. A frequency distribution of head capsule widths indicates CSM larvae probably develop through five instars. However, inter-instar ratios of head capsule widths did not conform to Dyar's hypothesis. Eggs deposited by females collected in the field and allowed to oviposit in the laboratory did not hatch at either room temperature or 6��C. However, cohorts of eggs hatched readily during incubation at either 10�� or 14��C when observed after two and three months exposure. Nine varieties of six commercially important species of grasses and cereals were evaluated for suitability as larval hosts. Annual ryegrass, Lolium multiflorum Lam., consistently supported the greatest population densities in the field and resulted in greatest survival of larvae in laboratory and greenhouse tests. Removal of annual ryegrass foliage in plots during late winter or early spring to simulate the effect of sheep grazing significantly reduced subsequent larval populations relative to plots without vegetation removal. / Graduation date: 1995

Public tendency, of late, is to reduce liberal use of harmful synthesized chemicals for promoting plant health. Today, biological control is becoming a commonly cited disease control option. Biological control agents (BCAs) not only control disease , but also promote plant growth. Application of biological control is based largely on knowledge of control mechanisms employed by antagonists, as well as the means of application that will ensure that an antagonistic population is established. Knowing the advantages is not the only factor that should be considered before application commences as, the disadvantages must be clearly outlined and explored further before a constructive decision as on implementation of biological control. A literature review was undertaken to provide the necessary technical information about biological control, its potential uses, methods of application, mechanisms of action employed, advantages and disadvantages associated with biological control application, public perceptions and the potential future of biological control. Diseases encountered within the KwaZulu-Natal Midlands on pasture and turf grasses were determined by a once-off survey conducted over 1999/2000. The aim of the survey was to determine broadly the management practices of farmers and groundsmen in KwaZulu-Natal and the potential impact of these on the occurrence of weeds, insects and diseases. The survey also addressed the level of existing knowledge about biological control and willingness to apply such measures. In the pasture survey, farmers were questioned about: soil type, grass species common used, irrigation , fertilization and liming, grazing programs and weed, insect and disease occurrences and control measures implemented. The same aspects were addressed in a survey to a representative sample of groundsmen (turfgrass production) , including also: topdressing, greens base used, drainage systems, mowing practices and decompaction principles. The survey showed correlation between pest incidence and management practices implemented. In terms of pest control, both farmers and groundsmen indicated a stronger preference to the use of herbicides , insecticides and fungicides. Use of fungicides for disease control by farmers is considered an often unfeasible expense, rather more emphasis was placed on implementing cultural control methods. At present farmers do not apply biological control strategies, but they did indicate much interest in the topic. Alternatives to current, or lack of current, disease management strategies are important considerations, with two new diseases identified in the KwaZulu-Natal Midlands just within the period of this thesis. Biological control strategies are implemented by 8% of the groundsmen surveyed, with emphasis being placed on augmenting the already present natural predators rather than the introduction of microbial antagonists. Although often mis-diagnosed by farmers Helminthosporium leaf spot is a common disease in the KwaZulu-Natal Midlands on Pennisetum clandestinum (kikuyu), This disease reduces pasture quality and detracts from the aesthetic appearance and wearability of turfgrasses. Helminthosporium leaf spot is incited by a complex of causal agents , Bipolaris was confirmed as the casual agent of Helminthosporium leaf spot on kikuyu at Cedara. Disease control by two BCAs, Bacillus (B. subtilis Ehrenberg & Cohn.) and Trichoderma (T. harzianum Rifai), as commercial formulations was tested against the fungicide, PUNCH EXTRA®. In vitro, Trichoderma was shown to be aggressive in controlling Bipolaris sp. In vivo, disease control achieved with Trichoderma kd was comparative with PUNCH XTRA® but not statistically different (P>=0.05). Trichoderma and Bacillus provided better disease control in comparison to an untreated control. Improved growth of Lolium sp. was determined in vitro, with Trichoderma kd and Bacillus B69 treatments. The microbe-based treatments accounted for growth stimulation, with significant (P<=O.05) growth differences noted. A microbial activator, MICROBOOST®was added to the treatments to improve microbial efficiency. Improved plant growth with MICROBOOST® applications was shown. Improved growth associated with microbial treatments, Trichoderma harzianum kd; Bacillus subtilis B69 and Gliocladium virens Miller, Gibens, Foster and con Arx. ,was also determined in vivo at Cedara, on L.perenne L., Festuca rubra L. and Agrostis stolonifera L. Establishment of a suppressive soil with antagonistic microbes resulted in significant (P<=O.05) effects on final grass coverage (except G. virens), as well increased root and shoot lengths (P<=O.05). Increased germination rates, as expressed in vitro, were not shown in vivo. Microbial activity with the application of MICROBOOST® showed little effect on germination but increased root and shoot lengths significantly (P<=O.05). Increased weed growth associated with the treatments (except G. virens) was considered a drawback of the microbial-treatments. Microbial treatments were also applied to pasture grasses. An in vitro grazing trial was established at Cedara, using L. multiflorum L. to evaluate the microbe-based treatments Trichoderma kd, Bacillus B69 and G. virens for improved pasture establishment and for increased grazing preference by Dohne Merino sheep. Trichoderma kd was associated with increased dry and wet biomass , but lower dry matter yields in comparison to the control. Only G. virens accounted for a higher dry matter percentage than the control. However, differences between the control and the microbial treatments was very small and not significant (P>=0.05). Of the three grazing observations made, sheep showed no grazing preference to plots with or without microbial treatments In general, the body of this research has shown that microbial treatments have the potential for increased disease control and growth stimulation of grasses. However, lack of significant differences between microbial treatments and controls has raised the question as to effect of external factors on microbial activity and survival, especially in vivo. This raises the question as to the validity of the use of microbial treatments where growth conditions cannot be controlled , remembering that the cost of establishment must be covered by the economic returns from utilization. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2003.

Indian ricegrass at the Desert Range Experiment Station forty-seven miles west of Milford, Utah, is damaged by the larvae of Coenchroa illibella, Diatrae sp. and Typoceris ceraticornis, the latter being the most destructive. The biology of the insects and the extent of damage inflicted are discussed. Uninfested plants produced more new stems than infested plants. Plants having a basal diameter of 4 to 6.9 cm and 7 to 9.9 cm were the most frequently infested and, consequently, the most severely damaged.