Use of Multiple Regression to Examine the Effect of Leaf Rust and Yellow Spot on Yield of Wheat in Northern New South Wales.

1985 ◽  
Vol 14 (4) ◽  
pp. 62 ◽  
Author(s):  
CR Wellings ◽  
PTW Wong ◽  
GM Murray
Keyword(s):  
Leaf Rust ◽  
Multiple Regression ◽  
New South ◽  
New South Wales ◽  
Yellow Spot ◽  
South Wales

Susceptibility of Australian wheats to Pyrenophora tritici-repentis

1988 ◽  
Vol 39 (2) ◽  
pp. 141 ◽  
Author(s):  
RG Rees ◽  
GJ Platz ◽  
RJ Mayer
Keyword(s):  
New South ◽  
New South Wales ◽  
Yellow Spot ◽  
Final Evaluation ◽  
Screening System ◽  
Pyrenophora Tritici Repentis ◽  
Controlled Conditions ◽  
South Wales ◽  
Juvenile Plants ◽  
Juvenile Plant

The response of Australian wheats to yellow spot caused by Pyrenophora tritici-repentis has been examined under controlled conditions with a juvenile-plant screening system. About three-quarters of contemporary Australian wheats are highly susceptible to the disease and very few cultivars possess useful levels of resistance. Also, the majority of Australian wheats now undergoing final evaluation before releasing are highly susceptible to yellow spot. Modern wheats grown in Queensland and northern New South Wales are, as a group, more susceptible than those they replaced, and this may have contributed to the upsurge in yellow spot in the region. In two comparisons between ratings on juvenile plants under controlled conditions with field disease assessments and yield measures, the juvenile plant ratings and field disease assessments explained similar proportions of the variation in yield measures.

History of outbreaks of the Australian plague locust, Chortoicetes terminifera (WALK.) between 1933 and 1959, and analysis of the influence of rainfall on these outbreaks

1962 ◽  
Vol 13 (4) ◽  
pp. 674 ◽  
Author(s):  
M Casimir
Keyword(s):  
Multiple Regression ◽  
New South ◽  
New South Wales ◽  
Regression Equations ◽  
Relative Significance ◽  
Early Season ◽  
South Wales ◽  
Outbreak Areas ◽  
History Of ◽  
Australian Plague Locust

An account of the history of outbreaks of the Australian plague locust, Chortoicetes terminifera, is presented for the period 1933–1959 from published information and records maintained by the New South Wales Department of Agriculture. Population fluctuations during this period have been examined in relation to rainfall for seven of the major and intermediate outbreak areas in New South Wales. It has been shown that rainfall during the months August to December is important in its influence on locust numbers the following season, whereas that occurring between January and April is apparently not. Subnormal "early season" rainfall favours an increase in the locust population of an area in the next season, while above-normal rainfall favours a locust decrease in the following season. In each of the outbreak areas selected there was a significant negative correlation between the current first locust generation of the season (measured in terms of an arbitrary scale or index) and preceding early season rainfall; and the estimated regression lines due to the two variables in each area were apparently parallel, although not coincident. A multiple regression analysis was carried out incorporating the preceding autumn locust generation as an extra independent variable. When the Culgoa-Barwon outbreak area was eliminated from the analysis, it was found that the regression equations for each of the six other areas could be considered identical, even to the constant term, any differences between areas being attributable to differences in the values of the independent variables. A single multiple regression equation based on the data for the six areas combined was calculated, and it is suggested that this can be used to forecast approximately the size of the spring locust generation in time to plan appropriate control measures. Difficulties inherent in the data are pointed out and the disturbing influence of invasion of one area by migrating swarms from another discussed. It is believed that more refined methods of estimating locust numbers and greater knowledge of locust behaviour in relation to long-term rainfall influences would allow predictions of much greater accuracy to be made, based on the correlations established in the present paper. The relative significance of outbreak areas situated mainly in the Central Division of New South Wales and those in far western parts of New South Wales and Queensland is discussed. It is suggested that two of the most serious outbreaks on record were the result of long-range migratory flights from the latter areas. The importance of these areas as a source of outbreaks affecting South Australia, Victoria, and southern New South Wales is also emphasized, and a tentative explanation of the role of early season rainfall in these arid regions is given.

Pathogenic specialization of Puccinia hordei Otth. in Australia, 1966-1990

1995 ◽  
Vol 46 (1) ◽  
pp. 127 ◽  
Author(s):  
PJ Cotterill ◽  
RF Park ◽  
RG Rees
Keyword(s):  
Leaf Rust ◽  
Resistance Genes ◽  
New South ◽  
New South Wales ◽  
Puccinia Hordei ◽  
Resistance Sources ◽  
South Wales ◽  
Rust Pathogen

One hundred and fifty-four isolates of the leaf rust pathogen (Puccinia hordei), collected from infected barley plants in Australia between 1966 and 1990, were typed to determine virulence with respect to the resistance genes Rphl to Rph9, Rphl2 (Triumph) and several uncharacterized resistance sources. The Australian cultivar, Prior, reacted differentially to the isolates examined, and is believed to possess a gene which is also present in addition to Rph2 in Reka 1. Virulence and avirulence on Prior were designated P+ and P- respectively. Eleven distinct pathotypes (pt) were identified, with pt 243 P+ and 243 P- predominating in samples collected between 1966 and 1979. In the 1980s, pt 210 P+ was most commonly isolated from samples collected in Queensland and northern New South Wales, and although a range of different pathotypes was present in southern Australia, pt 200 P+ was most frequent in this region. Virulences to genes Rphl, Rph2, Rph4, Rph5, Rph6, Rph8, Rph9 and Rphl2 have been detected, and only Rph3 and Rph7 are likely to be of value in protecting future Australian barleys from the disease.

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