Browsing by Author "Stringer, JK"

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A database of pest and disease incidence for the sugar industry : SRDC final report BS126S
(BSES, 1999) Stringer, JK
This project established a system to collate, store and interrogate pest and disease data that are collected annually by Queensland Cane Protection and Productivity Boards (CPPBs). An Access database titled ‘Bugbuster’ was developed and this served as the template which was modified to accommodate the needs of individual CPPBs.
Best linear unbiased prediction as a method for predicting cross potential : SRDC final report BS119S
(1999) Stringer, JK
Until recently, BSES breeders used an empirical formula to assess the breeding potential of a parent (Hogarth and Skinner, 1986). Although this method uses data from many sources, it needs to draw on data accumulated for up to ten years to provide reliable estimates. An alternative is the statistical technique called Best Linear Unbiased Prediction (BLUP) which was developed to predict breeding values from dairy cattle data sets which are typically highly unbalanced and from diverse sources.The main objective of this study was to compare the relative efficiencies of BLUP and the existing empirical method for identifying superior sugarcane cross combinations. There was little difference in the agronomic performance of crosses selected using either BLUP or the empirical method but BLUP proved to be the quicker method and should allow more rapid progress from breeding and selection.
Chlorotic streak resistance screening in the Tully district
(ASSCT, 2016) Magarey, RC; Sevntek, K; Bull, JI; Stringer, JK; Zamora, R
CHLOROTIC STREAK DISEASE (CSD) was first recognised more than 85 years ago and is present in most cane-growing countries around the world. An important management strategy is the use of resistant varieties; past research has shown there is significant variability in resistance in the Australian sugarcane germplasm. Data are reported from a variety resistance screening trial conducted in the Tully district (2013–2015 period) that was subjected to at least five flooding events over a two-year period. Maximum ‘% stools diseased’ infection levels were over 60% in the most susceptible variety. Several current commercial varieties appear very susceptible, including Q241A and Q251A. The data show that a much higher disease incidence is evident when data on ‘% stools diseased’ are recorded rather than ‘% stalks diseased’. Recording data on a stools basis therefore may provide a shorter time frame for assessing varietal susceptibility. Crop inspections are also significantly easier using this parameter, especially in mature crops where symptom expression is often higher (and therefore desirable to undertake at this time). Major flooding events provide optimum conditions for disease transmission in field trials, as long as shoot survival is not unduly affected.
Development and application of spatial analysis to improve precision in selection trials : SRDC final report BSS231
(2004) Stringer, JK
In the early stages of selection, a sugarcane breeder tests a large number of genotypes. As the amount of planting material for each genotype for testing is typically limited, selections are usually made on small, unreplicated, single-row plots. Unfortunately, such designs are prone to errors arising from spatial variability and interplot competition, which, unless accounted for, can seriously bias variety estimates and reduce genetic progress.In this project, an approach to the simultaneous modelling of spatial variability and interplot competition is developed. This approach combines nearest-neighbour techniques to model spatial variability, together with the genotypic and phenotypic interference models to estimate interplot competition. The joint modelling and standard approaches are compared using 23 sugarcane data sets for cane yield. Agreement between the two approaches varied from approximately 38% to 90%. Hence, for some trials there would be large differences in the selections to be advanced to final assessment trials. Additionally, for two trials, the joint modelling approach was applied to cane yield and CCS data. The number of selections in common for sugar yield for the two approaches was compared. Approximately 43% and 75% of the clones were in common, indicating that appropriate modelling of interplot competition and spatial variability can have a very large effect on the varieties to be advanced to final assessment trials.This project has resulted in an improved selection system, and this is likely to result in increased genetic gain through the advancement of superior varieties to later stages.The project has formed the basis of a PhD thesis submitted to the University of Queensland.
Evaluation of methods of estimating breeding value of sugarcane parental clones : SRDC final report BS75S
(1996) Stringer, JK
BSES uses an empirically based index to assess the breeding potential of sugarcane (Saccharum spp.) parents and this may take many years to provide reliable estimates. A rapid and efficient method of assessing the breeding value of parents in early stage families is needed to increase the rate of population improvement.
Factors affecting the incidence of and damage caused by weevil borers : SRDC final report BS151S
(BSES, 1998) Stringer, JK; Telford, DE
This study has shown that sampling billets for weevil borer damage through the extraneous matter system of a sugar mill gives reliable data as it supports in field data collected by BSES. These data may allow the simple field assessments to be related to the entire mill area. This would benefit other mill areas who do not currently sample for weevil borer damage.
Field performance of transgenic sugarcane plants carrying genes for resistance to SCMV : final report BSS154
(2000) Smith, GR; Taylor, GO; Harding, RM; Stringer, JK; Cox, MC; Yoyce, PA
The field resistance of transgenic sugarcane plants to sugarcane mosaic potyvirus was successfully demonstrated, and a number of transgenic lines are available for consideration for agronomic evaluation. Some of the transgenic lines yielded significantly more tonnes sugar per hectare in this trial, but a firm conclusion about the overall performance of the transgenic lines compared to the parental clone can not be concluded due to the limitations of this trial. These plants contain the coat protein gene of sugarcane mosaic virus and prove that pathogen-derived resistance can be engineered into a genetically complex monocot. The precise molecular basis of the resistance appears to be RNA mediated. More research is necessary to prove this as a number of the resistant lines do not exhibit the usual RNA profiles of transgenic plants from other species which are virus resistant. A second pathogen-derived resistance gene, based on the virus replicase gene, is also capable of conferring virus resistance in sugarcane.Analysis of sugar and syrup produced from transgenic cane has revealed that no genes, native or transgenic, survive the laboratory production process. There is every confidence that this result would also be found with mill produced sugar, when the opportunity to mill transgenic sugarcane eventuates. There is now good scientific evidence to contribute to the debate that sugar manufactured from transgenic sugarcane plants is indistinguishable or substantially equivalent to sugar produced from non-transgenic plants.
Optimising productivity and variety recommendations through analysis of mill data : ASSCT peer reviewed paper
(ASSCT, 2016) Stringer, JK; Croft, B; Di Bella, L; Sefton, M; Nielsen, R; Larsen, P; De Lai, R; Davies, I
Production peaked in the Herbert River mills in 2005 but since then productivity has declined. Analysis of mill data in the Herbert has successfully identified groups of farms with similar productivity over time and the major factors associated with these groupings. The major finding of the study was that those growers who have adopted new farming systems had significantly higher productivity than those who use traditional practices. The impact of the Pachymetra resistance of previous varieties on yield of the current crop was also significant, suggesting this may be a major factor contributing to poor ratooning in the Herbert. In the small farm size groups, low and high performing growers had similar levels of % plant, % young crops, % old crops and % old varieties. However, the low and high performing groups varied significantly in terms of new varieties, suggesting that the small farm size low performing group were not adopting the new, more productive varieties to the same extent as the small farm size high performing group. Manager’s age was also an important factor associated with cane yields. Growers who regularly (five or six years out of six) obtained clean seed had more than 10% higher yields than growers who never or infrequently obtained clean seed and greater than 6% higher yields than growers who only obtained clean seed in three or four years out of six. Results from this research has allowed the Herbert Cane Productivity Services Limited (HCPSL) to design targeted extension strategies with the region. This will result in better variety recommendations and increase productivity.
Pachymetra root rot surveys of the Tully district update 2018 : ASSCT peer-reviewed paper
(ASSCT, 2019) Shannon, GJ; Magarey, RC; Macgillycuddy, L; Stringer, JK; Lewis, M
Pachymetra root rot is a soil-borne disease that impacts all sectors of the Australian sugar industry. The disease attacks the root system of sugarcane crops, affecting yields and leading to stool loss and shortened crop cycles, thus impacting the farming, harvesting and milling sectors. Monitoring the disease is, therefore, important so that optimised management practices are adopted, so bringing benefits to the entire value chain. A survey of the Tully district conducted in 2004 showed that pachymetra root rot was widely distributed across the Tully mill area; a second survey undertaken in 2013 sought to determine trends in disease incidence after some significant changes occurred in the cultivar mix. Crop resistance had shifted significantly with a change in cultivar resistance and there was a consequent increase in disease severity. Financial losses from reduced yield were estimated at $5.5 million in 2013; this compares to just under $1.0 million in 2004. This paper reports on a third survey in 2018 that is a five-year update to provide snapshot of the status of this disease in the Tully sugar industry. While the disease is still widespread, its severity has decreased with financial losses estimated to be $3.5 million.
Productivity performance of climatological sub-regions within the Tully Mill area : ASSCT peer-reviewed paper
(ASSCT, 2019) Stringer, JK; Skocaj, DM; Rigby, A; Olayemi, M; Everingha, YL; Sexton, J
Inter-annual climate variability has a significant impact on productivity in the Wet Tropics region. Climate also varies spatially, yet the impact on productivity is less well known. Two distinct climatological sub-regions (northern and southern) have been identified within the Tully mill area based on total annual rainfall and annual average daily radiation. The wetter northern sub-region is characterised by lower radiation, lower temperatures and higher rainfall than in the drier southern sub-region. Mean cane and sugar yields were analysed for the two climate sub-regions using block productivity data obtained from Tully Sugar Limited for 2000 to 2017. After excluding 2011 (Tropical Cyclone Yasi), only farms with 15 or more years of data were included. The impact of spring-summer (SONDJF) rainfall and El Niño Southern Oscillation (ENSO) phases on cane and sugar yields in the two climate sub-regions was also analysed. On average, the northern, wetter climate sub-region yielded less cane and sugar yield than the southern, drier sub-region. There were significant differences between SONDJF rainfall terciles (dry, normal and wet) and ENSO phases (El Niño, Neutral and La Niña) for cane and sugar yields in the two climate sub-regions. Cane and sugar yields were significantly lower in years experiencing high SONDJF rainfall or in the La Niña phase. This analysis validates the results of the analyses used to derive the two climatological sub-regions in Tully. Improved knowledge of how climatic conditions influence sub-regional productivity performance will assist industry extension programs and on-farm management decisions.