Crop and Pasture Science
Volume 64 Number 8 2013
Cotton Catchment Communities CRC – Research Outcomes & Innovation (Part 1)
CP13070IPM in the transgenic era: a review of the challenges from emerging pests in Australian cotton systems
The dramatic uptake of Bt transgenic cotton led to effective control of Helicoverpa spp., and a dramatic reduction in insecticide use. Ironically this allowed several sucking pests, not affected by the Bt proteins, to emerge as important pests. The lack of scientifically derived management recommendations for these pests led to crop managers taking pesticide driven risk adverse strategies. This paper tells the complex story of the Cotton Catchment Communities Cooperative Research Centre’s efforts to address this gap and re-establish a strong IPM ethos in the Australian cotton industry.
CP12382An assessment of alternative cotton fibre quality attributes and their relationship with yarn strength
Cotton fabric manufacturers require stronger cotton yarns so they can knit and weave fabric more efficiently. While standard cotton fibre quality parameters relate to yarn strength, new alternative measures of fibre fineness and tensile properties are available that allow the yarn strength potential of cotton fibre to be better predicted. Such tools can be used by spinners for managing cotton bales, and by researchers developing new cotton varieties to produce better fibre.
CP13060Integrated pest management in cotton: exploiting behaviour-modifying (semiochemical) compounds for managing cotton pests
This paper reviews work on novel products for cotton pest management carried out in successive Cotton CRCs from 1998 to 2012. The paper describes the development of a long-range attract-and-kill product for Helicoverpa spp. moths, Magnet®, which is based on plant volatiles and is the first such product to be registered anywhere. The paper also describes the development of Sero X®, a directly toxic, short-range deterrent and anti-feedant product, which has good activity against Helicoverpa spp. and many sucking pests, and is currently being submitted for registration with Australian Pesticides and Veterinary Medicines Authority.
The data collected from three decades of disease surveys illustrates the impact of changes in farming practices, variations in seasonal weather conditions and the introduction and adoption of resistant varieties on the incidence and severity of the significant diseases of cotton in Australia. The survey results document the elimination of bacterial blight, the rise and fall in the incidence of Verticillium wilt and the emergence and spread of Black root rot and Fusarium wilt. Research efforts have been justified and the effect of control strategies have been measured by disease survey results.
CP13109Managing glyphosate resistance in Australian cotton farming: modelling shows how to delay evolution and maintain long-term population control
Herbicide resistance is an increasingly important problem in intensive broadacre agriculture worldwide. We used a model of herbicide resistance evolution to investigate how glyphosate-centric cotton farming in Australia could be altered to delay and manage glyphosate resistance. The model predicted that most scenarios result in resistance within two decades. Some feasible strategies can, however, be devised using the model’s predictions, offering the cotton industry the chance to extend the usefulness of this important herbicide, and manage resistant populations in the medium to long term.
The herbicide glyphosate has largely replace most other weed control methods in glyphosate-resisant cotton and summer fallows. We undertook a weed survey to determine what the effect of this reliance on glyphosate has had on weed species composition after a decade of use of glyphosate-resistant cotton varieties. We found a major increase in flaxleaf fleabane (Conyza bonariensis) in both cotton and fallow, and a minor increase on sowthistle (Sonchus oleraceus), these species and a number of others were poorly controlled and are likely to evolve glyphosate resistance and a shift to glyphosate tolerant species.
CP12374Soil organic carbon concentrations and storage in irrigated cotton cropping systems sown on permanent beds in a Vertosol with restricted subsoil drainage
We studied soil organic carbon changes in cotton rotations under varying stubble management practices in an irrigated grey cracking clay soil with poor subsoil drainage. The experimental treatments were: cotton–cotton; cotton–vetch; cotton–wheat, where wheat stubble was incorporated; and cotton–wheat–vetch, where wheat stubble was retained as surface mulch. Carbon concentrations and storage were similar among all cropping systems. Net carbon sequestration rates did not differ among rotations and did not change significantly with time in the 0–0.3 m depth.
CP13078The effect of sodicity on cotton: Does soil chemistry or soil physical condition have the greater role?
Soil sodicity reduces the growth of cotton across much of Australia’s irrigated production zones. Poor soil physical structure, not an unbalanced soil solution chemistry, is identified as the chief cause of reduced cotton yield. Further research into soil physical amendments is required to improve cotton yields rather than simply adding more fertiliser.
CP13093Impact of waterlogging on the nutrition of cotton (Gossypium hirsutum L.) produced in sodic soils
Waterlogging frequently occurs in flood-irrigated cotton crops grown in sodic soils, reducing nutrient availability and yield. This study suggests that root activity recovers more slowly with increasing sodicity, and that this is further exacerbated by waterlogging due to the longer time taken for aerobic conditions in the root-zone to return. More consideration of management options to deal with soil physical constraints is warranted because simply increasing fertilizer application is unlikely to overcome reduced cotton yield in sodic soils.
CP13025Growth and phosphorus uptake of faba bean and cotton are related to Colwell-P concentrations in the subsoil of Vertosols
The northern grains region (NGR) of eastern Australian is responsible for approximately 95 % of Australia’s annual cotton production. Historically, the application of phosphorus (P) fertiliser to cotton systems have been variable and unpredictable. This study found the concentration of bicarbonate extractable P in the subsoil layer was related to crop biomass and tissue P concentration. However, no individual P fertiliser placement strategy was superior for crop P uptake.
This is the first attempt to critically identify factors that are of greater or lesser importance in contributing to lint yield and fibre quality across the Australian cotton industry. Lint yield was significantly influenced by cultivar and growing region and the interaction between region, nitrogen, phosphorus, plant stand, rainfall and irrigation and season length. Changes have occurred from 2004 to 2011 in nitrogen and phosphorus application, lint yield increased under irrigated systems and decreased under dryland systems while all fibre quality parameters were base grade or better.
CP13139Maximum ambient temperature can influence carbon storage in Vertosols sown with cotton-based farming systems
The influence of average annual maximum temperature on carbon storage in clayey soils was studied by re-evaluating results from experiments conducted in NSW and Queensland. In general, variation in carbon storage with average maximum temperature was described by bell-shaped curves, and occurred at peak rates within a limited temperature range. The decrease or absence of change with time reported in many studies may be due to carbon storage occurring within a limited temperature range, whereas maximum temperatures can range widely within a season.