The impact of legumes after 21 years of rotation (11 legume crops) continue to positively impact soil health. The addition of a legume in a cotton rotation impacts all aspects of the cotton production. The evidence was clear from the soil N status and plant accumulation of N (nitrogen use efficiency (NUE), Carbon:Nitrogen (C:N) ratio and Apparent Nitrogen Fertiliser Recovery (ANFR)), yield, fibre quality to seed nitrogen and protein content. The most significant benefit of including a legume was evident when a legume followed a summer and winter fallow before the next cotton crop was sown (CV~C and CF~C). The long fallow allowed for the legume crop to reach optimum biomass production and time for the fixed atmospheric N to be mineralised and available for the following cotton crop. The addition of wheat into the cotton rotation also had a positive impact when compared to the continuous-cotton rotation. The impact from adding wheat was not as beneficial as a legume, however there were benefits by adding wheat into the cotton system.

This long term rotation experiment at ACRI, established by the late Dr Ian Rochester in 1994, has assisted with the understanding of soil and plant nutrition interactions. It has been a pivotal site in developing the industry crop nutrition requirements (especially N) but has evolved over the years to include the following research initiatives and outcomes:

- Advancing the understanding of legumes and their role in cotton crop systems.

- The role of stubble management in soil fertility.

- Improving the understanding of fertilisers (the role of timing, application and type) in increasing cotton productivity.

In recent times the site has also been important to the following research initiatives

- The dynamics of soil carbon in various rotation systems. (Data published from 1998 to 2008 reported the only increase in soil carbon under a cotton farming system in Australia).

- Greenhouse gas emissions from various cotton rotations and N application practices.

- Increasing attention on soil microbiology because of the sites high fertility.

- The response of cotton genotypes to various fertility regimes.

The 2016/17 season was the first time a Bollgard® 3 variety had been sown in the long term trial. The new variety responded to high rates of N and positively to the legume rotations. The fitted curves for N rates and N uptake revealed a positive linear relationship for the new Bollgard® 3 variety for the cotton-vetch-summer and winter fallow-cotton rotation. This is something to investigate for Bollgard® 3 response under a legume rotation. Under the continuous cotton rotation, the optimum N rate was calculated as 407 kg N/ha, however only yielding 12 bales/ha. In comparison the CV~C rotation only required 147 kg N/ha to achieve a much higher 14 bales/ha. The new variety responded positively to both vetch and faba bean in rotation and continued to follow the trend to the previously sown Bollgard® II varieties.

The green mirid, Creontiades dilutus (Hemiptera: Miridae), is a serious pest of cotton in Australia (Adams and Pyke, 1982). Minds are sucking insects which feed preferentially on the actively growing points of young plants. The damage they inflict to the tips of pre-squaring cotton and to early squares can result in delayed maturity of the plants and a reduced yield (Bishop, 1980). Current control of the green mirid relies on early season chemical sprays. The use of chemical insecticides is disruptive to beneficial insect populations as well as being expensive and environmentally harmful. One new strategy for insect control is the use of genetic engineering to produce plants resistant to insect attack. Chemical control of Heliothis armigera has already been augmented with the use of cotton plants expressing Bacillus thuringiensis (Ali and Young, 1993). A similar strategy for control of the green mind would be a desirable alternative to chemical insecticides.

The advent of round module picking, has created the opportunity to conduct 'large plot' replicated experiments at a field scale. However, accurate assessment of plot yield requires the ability to weigh the odd-sized round modules that are produced. Drive-on load cells offered a way of weighing these round modules as they are carried by three point linkage grab devices used on most farms. The tractor can simply drive over the scales carrying the module to accurately define its weight. Drive-on load cells would also be useful for weighing grain chaser bins and conventional basket pickers or boll buggies.

This capital item purchase will enable the weighing of cotton and grain yields from various cotton research projects conducted by Queensland Department of Agriculture and Fisheries and their collaborators.A set of four load cells complete with remote digital readout were purchased for the purpose of weighing a wide range of agricultural equipment (tractors, basket pickers, grain bins) on-farm on a range of ground surfaces. These load cells enable the quick and efficient assessment of crop yield whether it be in the form of round modules carried by tractors, basket pickers or boll buggies for conventional equipment and grain chaser bins.

Accurate yield assessment is essential for large scale on-farm research experiments, and these scales have the capacity to weigh equipment up to 40T with accuracy of +/- 40 kg. They also have a remotely­ located d igital readout, which avoids the need for cables that could easily be damaged during usage or transpoti, and the load cells are portable with inbuilt ramps, a carry handle and a weight of 27 kg each.

The green mirid, Creontiades dilutus (Stal), is one of the key early season pests on cotton in Australia. Adults and nymphs feed preferentiality on the meristematic tissue (both apical and axillary buds) of the cotton plant (Bishop, 1980). Severe infestations cause cotton plants to lose squares and also cause damage to growing tips, resulting in significant delays in growth and maturity of the plant(Adams and Pyke, 1982; Chinajariyawong et al 1988; Khan 1995 unpublished data). This delay can lead to loss in yield and/or quality. Currently, populations of green minds in commercial cotton are suppressed by insecticide sprays (mainly synthetic pyrethroids, organophosphates, cyclodienes and carbamates) applied for helicoverpa spp. In high infestations, dimethoate is the only effective insecticide available for green mirid control. The use of these insecticides early in the season disrupts beneficial insect activity and deters any chance of a true integrated pest management (IPM) program being developed for cotton. However, with the proposed introduction of Ingard (transgenic) cotton by Monsanto in Australia by 1997/98, it is expected that synthetic insecticide use on cotton will be reduced and green mirids may assume greater importance in the Australian cotton industry as they are unaffected by the Bt toxin in these plants. Green mirid infestations of Ingard cotton may therefore require the use of synthetic chemicals for control. Chemicals will disrupt the natural enemies of cotton pests and flare mites, aphids and other pests. If these things do happen, then Ingard cotton will require the same insecticide strategy as normal cotton to manage secondary pests. However, to realise the full benefits of the Ingard technology, growers should use new management techniques for green minds which do not rely on insecticides.

The spring edition of CRDC's magazine, Spotlight, brings you the highlights from the 2018 Australian Cotton Conference and its program of quality industry, research and external speakers.

This edition also takes a look at CRDC's investment into industry leadership, and our support for future leaders. With Cotton Australia and Auscott, we are pleased to announce Fleur Anderson and John Durham as our 2018 participants in the Australian Rural Leadership Program, and with Cotton Australia, a new crop of 16 Australian Future Cotton Leaders. We also recognise NSW DPI scientist Dr Robert Mensah, who received a Queen’s Birthday Honours Public Service Medal for outstanding public service to the NSW primary industries sector over 26 years.

This edition of Spotlight also has a range of articles based on research information to assist growers and consultants with ongoing improvements to crop nutrition and pest management. There is a strong cohort of CRDC-supported researchers continuously bring new information about nitrogen use which we’ve outlined. There is also a strong contingent of growers and consultants who, supported by CRDC Grassroots Grants, are sharing a wealth of experience in managing key pests to growers in other regions. And as we move into a new season it is a timely reminder to consider the likely consequences of early season pest management decisions and their impacts later on in the crop.

Spolight artile:Many cottongrowers have been improving environmental management on farm in recent years and in doing so have gained benefits for productioni

The aim of this training was to build industry biosecurity capacity and provide a gap analysis for boll weevils. Participants worked through the process of an incursion and eradication, with PHA facilitating the scenario.

*see PHA1702

The cotton fields are considered to be a biologically 'sterile' environment because of the constant use of pesticides and herbicides, however little work has been done to document the potential benefits of altering crop management practices which may result in less reliance on chemicals, greater soil biodiversity, and improved soil structure. Studies in southern Australia (Haines and Uren 1990, Rovira et al 1987) have shown rotations and conservation tillage to double the presence of soil fauna. Haines and Uren (1990) also noted improvements in soil structural properties which was seen to be a consequence of increased soil biological activity .

This report presents the results of an impact assessment of a cluster of six Bt Technologies projects funded by the Cotton Research and Development Corporation (CRDC) over the years ending June 2010 to 2018. In addition to CRDC funding (a combination of statutory levies paid by industry participants and matching Commonwealth funding), other resources were provided by research organisation contributions.

Methods

The six individual projects were first analysed qualitatively within a logical framework that considered project rationale, objectives, activities/outputs, outcomes, and impacts. Project Principal Investigators made comments on, and further inputs to, these logical frameworks. Some of the impacts identified through this process were then valued in financial terms. Benefits were estimated for a range of time frames up to 30 years from the year of last investment (2017/18). Past and future cash flows, expressed in 2016/17 dollar terms, were discounted to the year 2016/17 using a discount rate of 5% to estimate investment criteria. Investment criteria reported included Present Value of

This Guide provides you with a comprehensive summary of the key cotton crop protection issues, and is brought to you by CRDC and the Australian cotton industry's joint extension program, CottonInfo, in partnership with Crop Consultants Australia (CCA).