Digitized by Kansas Correctional Industries

Bibliography: leaves 186-210.

The effect of foliar applied potassium chloride on Septoria tritici on winter wheat was quantified and possible modes of action investigated by in vitro, glasshouse, controlled environment and field experiments between 1996 and 1999. In vitro experiments showed that as the concentration of potassium chloride increased, mycelial growth and germination of conidia decreased (EO sos of 1.36M and 0.7M, respectively). One glasshouse and two field experiments showed a significant reduction in the leaf area affected by S. trttict after foliar application of potassium chloride compared to untreated controls. In general, application of potassium chloride reduced the leaf area affected by S. tritici by 20 -.40%. However, a significant yield increase was not observed. Potassium chloride applied to the lower leaves of winter wheat did not confer systemic acquired resistance against S. tritici on the upper leaves. Inhibition of conidial germination, on leaf surfaces by potassium chloride was observed. Similar inhibition was observed when polyethylene glycol, an inert osmoticum, was applied at the same calculated osmotic potential. During field experiments there was no significant difference in the leaf area affected by S. tritici in plots treated with potassium chloride or polyethylene glycol, although both significantly reduced the leaf area affected compared to untreated control plots. Therefore, the principal mode of action of potassium chloride was proposed to be as a result of adverse osmotic conditions caused by the salt on leaf surfaces. However, the addition of a range of adjuvants to potassium chloride did not increase the efficacy of S. tritici control in glasshouse studies. The results from this study show that potassium chloride, when applied to foliage of winter wheat can reduce the leaf area affected by S. tritici and it is proposed that this reduction was by adverse osmotic conditions caused by the salt on leaf surfaces.

The use of wood-based composites has increased dramatically over the last two decades due to a number of factors. One reason is that Oriented Strand Board (OSB) is being increasingly utilized in residential applications in place of plywood. However, the use of OSB in residential construction is often limited because of its susceptibility to attack by biological pathogens such as mold and decay fungi. The environmental conditions that exist in certain use categories can be so adverse that the performance of these composites is negatively affected. This study was divided into two parts. The first phase examined the effectiveness of fungicides or combinations of fungicides (including some metal-containing preservatives) for enhancing the mold resistance of strandboard. During the second part of the study, preliminaryexperiments investigated the effectiveness of fungicides or combinations of fungicides using anagar-block test to estimate the preservative toxic threshold retention. The compatibility of the fungicide on the resin curing was studied by measuring change in the resin gelation and viscosity. After these screening experiments were completed, large size boards were prepared and mechanical and decay resistance properties were examined. It was found that mold and decay resistance properties of strandboard directly were related with the biocide type and its concentration. Greater protection of the strandboard was achieved with an increase in preservative retention levels. However, due to the relatively high cost of non-metallic (organic) preservatives, it is important to find the minimum amount of preservative that can protect the OSB against mold and decay fungi. One method of reducing the cost and increasing efficacy is to combine different fungicides to determine whether synergism exists. Even if synergism does not occur, it may reduce the overall cost by combining a less expensive biocide with a smaller amount of a more expensive biocide wheretheir biocidal efficacy complements each other. In addition, it is important to understand that high retention of preservative may also cause negative effects on the mechanical properties of strandboard. This maybe noticeable of the high retention level of the biocide when a greater negative effect on the internal bonding (IB) strength may be recorded. Lower IB strength for treated strandboard may be attributed to the formulation of chemical residue in the wood surface, which may interfere with the reaction between wood and phenol formaldehyde (PF) resin. Surface-active agents in the preservative may also cause the PF resin to over-penetrate into wood decreasing bond strength. Increasing moisture content of strands by the introduction of an emulsified aqueous biocide solution, may cause dilution of the resin, and reduced bonding. It should also be noted that high retention of preservative which cause a change in the viscosity and gelation time of PF resins would be problematic for the operation of an OSB plant. For viscosity change, it could significantly affect the flow properties of the resin on the wood furnish and its atomization as it is spraying onto the wood furnish. In addition, it may require further modification to the equipment that supplies the resin to the spray nozzle. For changes in the gelation time, this may require changes to the press time at the OSB plant.

No description available.

The use of wood-based composites has increased dramatically over the last two decades due to a number of factors. One reason is that Oriented Strand Board (OSB) is being increasingly utilized in residential applications in place of plywood. However, the use of OSB in residential construction is often limited because of its susceptibility to attack by biological pathogens such as mold and decay fungi. The environmental conditions that exist in certain use categories can be so adverse that the performance of these composites is negatively affected. This study was divided into two parts. The first phase examined the effectiveness of fungicides or combinations of fungicides (including some metal-containing preservatives) for enhancing the mold resistance of strandboard. During the second part of the study, preliminaryexperiments investigated the effectiveness of fungicides or combinations of fungicides using anagar-block test to estimate the preservative toxic threshold retention. The compatibility of the fungicide on the resin curing was studied by measuring change in the resin gelation and viscosity. After these screening experiments were completed, large size boards were prepared and mechanical and decay resistance properties were examined. It was found that mold and decay resistance properties of strandboard directly were related with the biocide type and its concentration. Greater protection of the strandboard was achieved with an increase in preservative retention levels. However, due to the relatively high cost of non-metallic (organic) preservatives, it is important to find the minimum amount of preservative that can protect the OSB against mold and decay fungi. One method of reducing the cost and increasing efficacy is to combine different fungicides to determine whether synergism exists. Even if synergism does not occur, it may reduce the overall cost by combining a less expensive biocide with a smaller amount of a more expensive biocide wheretheir biocidal efficacy complements each other. In addition, it is important to understand that high retention of preservative may also cause negative effects on the mechanical properties of strandboard. This maybe noticeable of the high retention level of the biocide when a greater negative effect on the internal bonding (IB) strength may be recorded. Lower IB strength for treated strandboard may be attributed to the formulation of chemical residue in the wood surface, which may interfere with the reaction between wood and phenol formaldehyde (PF) resin. Surface-active agents in the preservative may also cause the PF resin to over-penetrate into wood decreasing bond strength. Increasing moisture content of strands by the introduction of an emulsified aqueous biocide solution, may cause dilution of the resin, and reduced bonding. It should also be noted that high retention of preservative which cause a change in the viscosity and gelation time of PF resins would be problematic for the operation of an OSB plant. For viscosity change, it could significantly affect the flow properties of the resin on the wood furnish and its atomization as it is spraying onto the wood furnish. In addition, it may require further modification to the equipment that supplies the resin to the spray nozzle. For changes in the gelation time, this may require changes to the press time at the OSB plant.

Thesis (M. Ag. Sc.)--University of Adelaide, 1985. / Some ill. mounted. Includes bibliographical references (leaves 86-92).

Thesis (M. Sc.)--University of Western Sydney, Hawkesbury.

Thesis (Ph.D.)--University of Adelaide, Dept. of Environmental Science and Management, 1998. / Bibliography: leaves 186-210.

Thesis--Auburn University, 2007. / Abstract. Vita. Includes bibliographic references (p.61-68).