Diminishing water supply, changing weather patterns and pressure to enhance environmental flows are making it imperative to optimise water use efficiency (WUE) on cotton/grain farming systems. Growers are looking for better strategies to make the best use of limited water, but it is still not clear how to best use the available water at farm and field scale. This research project investigated the impact of management strategies to deal with limited water supplies on the yield and quality of irrigated cotton and wheat. The objectives were: (1) to develop irrigation management guidelines for the main irrigated crops on the Darling Downs for full- and deficit irrigation scenarios, taking into account the critical factors that affect irrigation decisions at the local level, (2) to quantify the evapotranspiration (ET) of Bollgard II cotton and wheat and its relationship to yield and quality under full- and deficit-irrigation scenarios, and (3) to increase industry awareness and education of farming systems practises for optimised economic water use efficiency.

Objective (1) was addressed by (A) collaborating with ASPRU to develop the APSFarm model within APSIM to be able to perform multi-paddock simulations. APSFarm was then tested by conducting a case study at a farm near Dalby, and (B) conducting semi-structured interviews with individual farmers and crop consultants on the Darling Downs to document the strategies they are using to deal with limited water. Objective (2) was addressed by (A) building and installing 12 large (1 m x 1m x 1.5 m) weighing lysimeters to measure crop evapotranspiration. The lysimeters were installed at the Agri-Science Queensland research station at Kingsthorpe in November 2008, (B) 16 conducting field experiments to measure crop evapotranspiration and crop development under four irrigation treatments, including dryland, deficit-irrigation, and full irrigation. Field experiments were conducted with cotton in 2007-08 and 2008-09, and with wheat in 2008 and 2009, and (C) collaborating with USQ on a PhD thesis to quantify the impact of crop stress on crop evapotranspiration and canopy temperature. Glasshouse experiments were conducted with wheat in 2008 and with cotton in 2008-09. Objective (3) was addressed by (A) conducting a field day at Kingsthorpe in 2009, which was attended by 80 participants, (B) presenting information in conferences in Australia and overseas, (D) presenting information at farmers meeting, (E) making presentations to crop consultants, and (F) preparing extension publications.

As part of this project we contributed to the development of APSfarm, which has been successfully applied to evaluate the feasibility of practices at the whole-farm scale. From growers and crop consultants interviews we learned that there is a great variety of strategies, at different scales, that they are using to deal with limited water situation. These strategies will be summarised in the “Limited Water Guidelines for the Darling Downs” that we are currently preparing.

As a result of this project, we now have a state-of-the-art lysimeter research facility (23 large

weighing lysimeters) to be able to conduct replicated experiments to investigate daily water use of a variety of crops under different irrigation regimes and under different environments. Under this project, a series of field and glasshouse experiments were conducted with cotton and wheat, investigating aspects like: (A) quantification of daily and seasonal crop water use under nonstressed and stressed conditions, (B) impact of row configuration on crop water use, (C) impact of water stress on yield, evapotranspiration, crop vegetative and reproductive development, soil water extraction pattern, yield and yield quality. The information obtained from this project is now being used to develop web-based tools to help growers make planning and day-to-day irrigation decisions.

This project aimed to identify means to improve nutrient use‐efficiency in Australian

cotton production systems and to improve soil health/fertility. The NutriLOGIC DSS

provides an updated resource for cotton growers to manage soil fertility and cotton

nutrition. This program provides recommendations to optimise crop nutrition

through interpreting soil and plant analyses.

N use‐efficiency has been benchmarked and indicates the cotton industry

substantially over‐uses N fertiliser. The industry can safely reduce N fertiliser inputs

by about 25% without reducing yield.

The cotton industry can become carbon positive by adopting minimum tillage

practices, by incorporating all crop stubble, by including legume crops in the

rotation and reducing fallow times. Producing cotton using sustainable soil and crop

management and reducing our net CO2e emissions will greatly assist marketing

Australian cotton.

Soil health can be improved dramatically with legume cropping. Marked

improvements can be seen in the soil physical environment, chemical fertility and

biological activity in those cropping systems that include legumes. For example, the

cotton‐vetch‐fallow‐cotton rotation remains the highest‐yielding system and requires

very little N fertiliser and therefore produces low carbon emissions.

H. armigera is one of the major pests faced by the Australian cotton industry. Widespread uptake of transgenic Bt-cotton has reduced the costs and environmental and health impacts associated with the use of chemical insecticides to control this pest. However, genes for Bt-resistance have been detected in H. armigera, and the danger of resistance to the limited array of Bt toxins available to control Lepidoptera, means that novel biological methods of pest control continue to be of interest.

Recent advances in molecular biology have opened possible new control technologies. CSIRO‟s large genomics effort is delivering not only the complete genome of H. armigera, but has also sequenced many thousands of genes expressed in the midgut of larvae. Successful gene silencing by RNAi would allow us to exploit the genomics results for pest control. RNAi involves introduction of double-stranded RNA (dsRNA) into a target species, resulting in highly specific gene silencing. By reducing the expression of any essential gene, RNAi could be used as an effective method of protecting crop plants from insect damage or of controlling the propagation of the pest insects themselves.

Using the limited resources available to this project, we asked whether any evidence of RNAi-caused knockdown could be observed upon transient expression of dsRNA in plant tissue. This approach proved to be challenging for a number of reasons, and no consistent and significant evidence of RNAi was observed in any bioassay. A small number of H. armigera genes, all expressed in the larval midgut, were targeted. The first four are known to be essential genes, and the fifth is an enzyme specifically required for gossypol detoxification. Initial experiments were conducted to test biosassays of larvae on Nicotiana benthamiana. These control bioassays on different plants showed that larval growth on control and mock-treated plants was quite variable; even when older larvae were tested, no significant effects were observed. The variability observed demanded that we have found it necessary to find a better experimental system. Results of control experiments using cowpea were encouraging, but no evidence for RNAi was obtained upon transient expression of the dsRNA constructs. This work suggests that a full-scale project to evaluate genes for their effectiveness as RNAi targets will be required, making use of transgenic plants, such as Arabidopsis or tobacco in the first instance.

To determine the various factors affecting the loss of activity of insecticides on cotton over time. To detetemine the relative persistence of the range of insecticides used to control cotton pests, particularly Heliothis spp.

Following the success of CottonInfo researcher tours over recent years, the 2018 “Optimising Irrigation & Nitrogen” tour aimed to bring together researchers, industry, advisors and growers; with the objective of raising awareness of industry funded research programs, and promoting the latest best practice management.

Tour themes cover topical industry-wide issues, including management to optimise different irrigation systems, practices to maximise performance of irrigation systems, management practices to increase NUE, where N losses occur & impact of irrigation.

This project aimed to improve the profit of 3,000 cotton, dairy, rice and sugar irrigators with the support of 16 research and development partners and 19 farmer irrigation technology learning sites. Grower led irrigation research and extension aimed to collect commercially relevant comparative data on different irrigation systems and technologies. The intention was to provide growers improved understanding of the implications for capital investment, management and the resource requirements (water, energy and labour) associated with different irrigation systems and the adoption of automation technology and different approaches to farming systems.The project consistedof three components. 1.Practical, reliable irrigation scheduling technologies 2.Precise, low cost automated control systems for a range of irrigation systems3.A network of 19 farmer managed learning sites located around Australia.The project hadkey learning sites in Queensland; Ayr, Emerald, Warwick, Dalby, Toowoomba, St George. NSW; Moree, Narrabri, Wee Waa, Tamworth, Aberdeen, Whitton, Jerilderie. Victoria; Numurkah, Shepparton, Macalister. Goulburn Murray Irrigation District,Tasmania; Rocky Creek, Sisters Creek, South Riana, Montana, Cressy. South Australia; Allendale, Eight Mile Creek, Mt Schank. Western Australia; Harvey.The flagship strategy of the project was use of the key learning sites. These 19 sites were located all around Australia and were mostly on commercial farms. They all involved farmers, advisers, scientists and agribusiness. Thousands of people inspected or visited one of these sites. Some were more “research” focused; testing a hypothesis with robust scientific methods. Others were “demonstration” focused involving monitoring current actions and making changes as experience and confidence grew. One of the strengths of the project was having both approaches.Extension activities conducted by the project have resulted in the project being promoted to over 3000 irrigators and industry personnel at a range of field days, field walks and workshops.Severalactivities targeted sharing knowledge and collaborations across different sectors of rice, cotton, sugar and dairy. These included bus tours to other industries, social media, workshops and farm field days

In this investigation we have identified that approximately 30% of the sites in both years investigated are showing issues at depth with respects to root development and / or irrigation infiltration. There was broadly, two phenomena that have been identified in this study, those being; 1. Locations showing little or no root development during the period being investigated (crop year period) and/or 2. Locations showing depleted root development, or poor or nil irrigation recharge to the portion of the profile investigated during the crop year period. Further to our investigations it would seem that soil structure is being compromised and soil porosity lost either due to rain shifting salts down through the profile and causing a band of structural collapse, which links in to irrigation recharge issues, or is due to the increased frequency of irrigation causing increased dispersion and general structural decline of the soils in question, thus reducing root penetration, and moisture infiltration.

This study has identified spatially and temporally the extent to which these constraints to the production of cotton are an issue at an industry level. The findings of this study will allow the authors to focus future research efforts to investigate in more detail the causal factors behind the mechanisms identified. This research will also follow on to more detailed investigations as to how the mechanisms identified in this study are affecting plant root development and moisture infiltration again both spatially and temporally at field level .

* Testing various versions of SIRATAC on a commercial scale. * Ptoviding a database of the response of cotton to damage. *Comparing the response of the new varieties Siokra and DP90 with DP61.

This 3 year study examined the relationships between catches of Heliothis adults in monitoring traps and the abundance of eggs on cotton crops. In the first year paired traps of the two Heliothis species set up on the edge of cotton blocks showed a bias towards H. armigera in total catch compared with the proportion of the two species found in egg identification. The bias was greater with funnel than cone traps.

Since the first detection in the Dawson/Callide region of Central Queensland in 2012, reniform nematode has become a serious concern for cotton growers and researchers as well. Although reniform is considered one of the major diseases of cotton in the US, it is still considered a minor problem in the Australian cotton industry due to the limited scientific studies of the epidemiology of reniform in the Australian cotton cropping system. This project had a number of objectives to address knowledge gaps and obtain data to understand how the reniform nematode is interacting with cotton plants in Australian soil so that we can improve the management practice.

In this project, large numbers of cotton fields from both NSW and QLD have been monitored every season to confirm the presence or absence of plant-parasitic nematodes, and to provide an indication of possible nematode problems in the field. To understand the ecology of reniform nematode in Australian cotton, three glasshouse pot trials were conducted specifically to assess the vertical movement reniform nematodes in the vertisol soil, host/non-host suitability to different crops for reniform nematode, and effect of different reniform nematode population on growth and yield of different cotton varieties. The genetic diversity of the reniform populations found in different crops including cotton was compared to each other while it was also compared with international isolates. Additionally, three different field trials were conducted during this project period to investigate the effectiveness of seed treatment products (with nematicidal property) and a biological control agent to control the reniform nematode.

The seasonal field survey has provided information about the prevalence and spread of the reniform nematodes in Australian cotton fields. So far, reniform nematodes have been found in the cotton field in Central Queensland only. Early-season deep core samples (2018/2019 season) from different fields in Theodore shows the variable abundance of reniform nematode in the soil profile. In some fields, they were most abundant in the top 30 cm while some fields had a large population in the 30-70 cm below the surface. Interestingly, in some of the fields, the highest population was found at the depth of 70-100 cm below the soil surface. These results clearly show that the reniform can live and survive deep in the soil profile thereby providing a reservoir of nematodes that may reinfest the planting zone when cotton is sown. The vertical movement pot trial confirmed that the reniform nematode can move upward from deeper soil profile in the presence of a suitable host (cotton) once the seedling starts to grow.

The reniform population trial has provided some interesting results on the varietal response of cotton plants. Although all the varieties were treated similarly, reniform had a direct negative effect on growth (shoot biomass) and yield of variety ‘Sicot 714’ while ‘Sicot 746’ and ‘Sicot 748’ were not affected. This indicates the reniform nematode may significantly reduce the crop yield if the number of nematodes in the soil reaches a certain threshold and different cotton varieties may have different thresholds for reniform. The host/non-host trial has provided evidence that the rotation crops such as corn, forage sorghum, grain sorghum, and wheat are non-host of the reniform nematode. These crops were not infested by a reniform nematode, and interestingly, the reniform population in the soil of these crops was dropped to almost zero. Thus, crop rotation using any of these crops would be a good option to manage the reniform population in the field. It would be worthwhile to conduct a detailed field trial to evaluate whether similar results can be achieved in the field.

In the field trials, commercial seed treatment products with nematicidal properties had no effect on the reniform population in the soil. Similarly, another field trial with a biological product containing Bacillus species named FertiLink showed that this product has no effect on the nematode population in the soil.

The genetic diversity study has shown that the reniform nematodes found in different crops across Queensland are not different from each other. Although it is not clear if the nematodes on other crops are virulent to cotton, they may pose a great threat to the cotton field because of the cross-contamination of reniform nematodes from other crops to the cotton field. This study also confirmed that the Australian reniform population is not different than the international population, therefore the management practices from abroad can also be recommended in Australia.

The research results obtained during this project have been widely disseminated throughout the industry through presentations at different conferences and grower’s meetings.