Annual Report 1994-1995

Annual Report 1993-1994

This fact sheet has been adapted for CottonInfo from a former Cotton Catchment Communities CRC publication. It was originally authored by CSIRO, NSW DPI, Incitec Pivot and CRDC.

The result of the trials clearly shows that within the majority of cases the amount of lint produced from the amount of N applied is outside the optimum, highlighting that there is opportunity for increased production with current levels of fertiliser input if the influencing factors are better understood. In addition the results also showed that there are farming systems that enable NFUE to be optimised without sacrificing lint yield.

Nitrogen (N) nutrition of high yielding cotton crops remains one of the biggest production costs with improvement of nitrogen use efficiency (NUE) being somewhat of an enigma when trying to ensure that profitability and efficiency are both optimised. When attempts to improve NUE are centred on tweaking N rates, application timing and products only, the outcomes are frequently fruitless, confusing and seasonally contradictory. This is generally because they are made in the absence of close consideration of the other major factors that control NUE. NUE is not just related to N fertiliser practices but is intimately related to soil characteristics and condition, their reaction to irrigation practices, and weather conditions

The reniform nematode is a major constraint to cotton production in the USA. Recent detections in Central Queensland have led to an extensive soil survey of the Theodore district. Reniform nematodes were found to be widespread, inhabiting 72-75% of fields in the northern districts, 49% of sampled fields to the south of Theodore as well as a limited area in Emerald. Although summer/ winter fluctuations have been observed, there is some early indication of net population increases between cotton seasons. Further data collection is required to establish economic thresholds to enable prediction of potential yield decrease associated with a population density

The Society for Invertebrate Pathology annual meeting is the leading forum for the review of research and development of biopesticides and invertebrate pathology. Biopesticides based on baculoviruses such as Vivus and Gemstar have been of significant benefit to the cotton industry in management of Helicoverpa spp, but there remain very few researchers in Australia experienced in baculovirus biology. The conference encouraged new linkages between the attending researcher and international researchers in the field, increasing the flow of information into Australia. A showcase of current research findings through a presentation on the application of next generation sequencing and bioinformatics in the characterisation of diversity and evolution of the Australian baculoviruses in commercial production by AgBiTech Australia. This work has implications for the stability of virus isolates used in the Australian cotton industry and in the registration of this and other isolates as biopesticides.

It is well-recognised that the pest status of Helicoverpa spp. moths within Australian cotton crops has been reduced by the use of Bt cotton varieties, and that much less insecticide is now directed against these pests. But how has the abundance per se of Helicoverpa spp. changed over time within cotton landscapes and how much of the observed change can be attributed to the use of Bt cotton ? Have the two key species, H. armigera and H. punctigera, been influenced to the same extent ? Does the large “spring” immigration of H. punctigera into eastern cotton production landscapes, from the inland where it is unlikely to be influenced by Bt cotton, still occur to the extent it was believed to do in past years ? In part to help answer these questions, CSIRO has been monitoring populations of Helicoverpa at landscape scale in the vicinity of ACRI, Narrabri (Namoi Valley) using pheromone traps since 1992. This work continued in this project.

Irrespective of any numerical suppression of these pests, the possibility of Bt resistance emerging in Helicoverpa spp. remains a major threat for the Australian cotton industry. A Bt Resistance Management Plan (RMP) was therefore established with the introduction of Bt cotton and is regularly reviewed for its effectiveness. Central to the RMP is the use of mandatory refuge crops (currently pigeon pea and conventional cotton) to release large numbers of Bt susceptible moths within cotton production landscapes and thereby limit the development of Bt resistance. At the inception of this project, unexpectedly high frequencies of resistance alleles (especially those for Cry2Ab) had been reported and seemed to be trending upwards, which was of much concern. Our previous research had identified the most productive (although highly variable) refuges. We had also shown that mandatory refuge performance in servicing landscapes with susceptible moths is likely to be very patchy and suggested that such would be inevitably weakened further by the industry decision to halve refuge area requirements. Other work had shown that mating of Helicoverpa moths is random with respect to plant host origin (the latter determined using stable isotope signatures that moths aquire from plants when feeding on them as larvae). Random mating was hitherto a key but untested assumption in the RMP. However, our understanding of the relative contributions of the various plant host origins of moths, be they Bt cotton crops, mandatory refuge crops or other [“unstructured”] refuges, to the total populations of moths throughout landscapes and regions, and the degree of movement / spatial mixing of such moths within and between such areas, is still rudimentary. Such information is critical to an effective RMP. In particular, the scales at which the movements and mixing occur (and their spatial consistency) are directly relevant to the optimal development and use of modelling tools to adequately predict the development of resistance and its management. What is the most appropriate scale to use in such modelling ? Possibly it’s landscape scale, or perhaps something larger is more befitting for very mobile insects ?

In addition, the efficacies of other aspects of the RMP, most notably the mandatory requirement of planting windows for Bt cotton (designed to limit the number of generations of Helicoverpa exposed to Bt toxins) and post-harvest “pupae busting” of Bt cotton (designed to reduce the over-winter survival of resistant Helicoverpa, i.e. from one season to the next), have been questioned. Much has changed in cotton production since the original development of the RMP, or is likely to in the near future (e.g. increased dry-land cotton, greater emphasis on soil health, new tools provided to manipulate crop growth & maturity, the future release of Bollgard 3® cotton with three Bt toxins) which put pressure on the perceived benefits of these RMP-related practices.

This travel exchange sponsorship funded the researcher to present t two international conferences, their paper based on the findings of the Legal Dimensions aspects of the Accelerating Precision Agriculture to Decision Agriculture Research Grant, as well as the broader project and project outcomes.

Currently, the legal and regulatory frameworks around agricultural data are immature. Around the world, many groups are grappling with how best to manage agricultural data and what best practice would look like for the governance of agricultural data which would enable producers to capture the value of their data and for agricultural industries to foster and support digital innovation. The aim of this international travel exchange was to disseminate the research findings of the Legal Dimensions of Digital Agriculture research funded as part of the P2D project as well as provide the opportunity to network and collaborate with researchers working on the agricultural data governance internationally. Interestingly, Australia was shown to be leading the discussion on agricultural data governance in the international context.

One of the key findings of a recent Australian wide research study, Accelerating Precision Agriculture to Decision Agriculture, funded by the Australian Government (Department of Agriculture and Water Resources as part of its Rural R&D for Profit programme) and all of Australia's 15 Rural Development Corporations is that a national approach to ag data governance is needed to ensure the benefits of digital agriculture are fully realised. While a fundamental part of the national approach is to ensure agricultural data is findable accessible interoperable and reusable, this discussion will focus on the unique interrelationships between Government, rural industries, agribusinesses, advisers and farmers in Australia that are posing challenges to how best to implement the FAIR principles to ensure on farm data sharing benefits not only third parties but the farmers themselves.

Deep drainage below irrigated crops wastes a scarce resource and can potentially lead to rising water tables and salinity. The lysimeter facility at the Australian Cotton Research Institute (ACRI) was used to measure deep drainage at 2.1 m depth under a furrow irrigated cotton-wheat rotation Drainage accounted for 11% of the irrigation. Two distinct types of drainage were observed - matrix and bypass. Bypass drainage was much faster and occurred immediately after irrigation. It accounted for most of the drainage. Drainage could arrive at the watertable at 16 m depth within 15 - 30 days. Bypass drainage was inefficient at leaching accumulated salt, but removed about 6% of the applied nitrogen