Summary Following square and boll loss, damaged plants may became taller and leafier than undamaged plants. Due to these changes, damaged plants may be better able to compete with their neighbours for light, water and nutrients. This explains why undamaged plants with damaged neighbours yielded about 50% less than undamaged plants with undamaged neighbours in field experiments at Narrabri. Yield reductions due to fruit loss could be greater than expected because of the negative influence of damaged plants on undamaged neighbours.

The key impact of this project for the Australian cotton industry was via the provision many of the essential knowledge foundations that assisted the rapid transition from a feasibility assessment with commercial partners at the Gilbert River to new cotton industry development at the Gilbert and the Ord Rivers (the later changing from sugar to cotton as the preferred crop). The move to cotton as the base crop for the expanded irrigation area at the Ord River was unexpected when the project started.

Tropical registration of Bollgard 3 with sowing windows and resistance management tailored to intra-regional abiotic and biotic risks was supported via expertise that identified all regions with a realistic potential to grow cotton within 10 years, the likely growing season and pest issues for each region and produced a map so distance between regions could be measured. This project also facilitated and supported efficacy studies of Bollgard 3 (VIP3A) on Spodoptera litura a key wet season pest in much of tropical Australia as there was no evidence of prior testing of this species. Following two years of screening it was concluded there would be little chance of survival of Spodoptera litura in the field.

A partnership was established to investigate cotton at the Ord River WA in 2017 following a workshop requested by local farmers and Ord expansion proponents on the prospects for growing cotton as a base crop. The workshop coincided with the impending registration of Bollgard 3 technology, the opportunity to develop well-drained levee soils on the west bank of the Ord suitable for wet season planted cotton and a climatic sweet spot analysis (conducted by this project) identifying mid-wet season as the optimal planting time. Securing funding from for the CRC-P project “Developing sustainable cropping systems for cotton, grains and fodder” (an objective of this CRDC project) expanded R&D activities in 2018. Results from research in 2017 & 2018 and test farming of 350 ha in 2018 were very promising with yields > 11 b/ha and above basis fibre quality when planted in the February ‘sweet spot’. Land development has commenced at Carlton Hill in October 2018 and planning for gin construction in late 2020 initiated by the developers.

Provided Technical support via soil characterisation and modelling analysis to two properties investigating dryland cotton cropping in the Gilbert Catchment Qld. The most suitable soil characteristics and optimal sowing window to produce reliable yield were identified. The best dryland crops in 2018 were grown on soil types with the characteristics identified in these analysis (well drained, deep uniform loamy-sand texture, minimal surface crusting).

This project contributed to DAQ1401 – “Strengthening the Central Highlands Cotton Production System” by climatic analysis, experimental design, data interpretation and analysis to support the August sowing opportunity. Presented at annual field days, review meetings & final report. The industry impacts of this project are now well documented.

Provided agronomic, climatic and technical support to many commercial and government agencies. Some will proceed with cotton in 2019 but are now more aware of the potential climatic risks and management challenges and have adjusted plans so a positive gross margin is possible in the worst case scenario (e.g. at Mareeba and the Burdekin). Other enquiries have not progressed due to time required for development or due to reassessment following climatic and resource analysis presented to them.

Central Queensland is geographically and climatically distinct from Australia’s other cotton production regions and as such presents both opportunities and challenges for cotton production and the farming system. This project examined the Emerald climate to identify opportunities that might enable the production of more consistent cotton yields and quality in what can be a highly variable climate.

The climatic analysis identified that spring and early summer is the most optimal period for boll growth and maturation. However, to unlock this potential requires unseasonal winter sowing that is 4 to 6 weeks earlier than the traditional mid-September planting time. Consequently our research investigated: (i) how much earlier can cotton be sown whilst maintaining reliable crop establishment, (ii) what benefits could accrue with earlier sowing both in terms of yield and quality and (iii) how should agronomic management be varied to optimise crop performance when sown early.

Data collected over 4 years has demonstrated that August sowing offers the potential to grow reliably higher yields compared to the traditional spring planting window with an average improvement of 2.2 b/ha per annum (23%) with no additional outlay except extra seed costs at planting. Earlier sown crops have proven to be easier to manage, as boll setting is confined to more favourable spring and early summer conditions. A measured benefit has been an average saving of 0.9 ML/ha pa over three years for the irrigation water required.

The other surprising outcome from this research has been the reliably poorer yields achieved from the mid-September sown cotton treatments over four years. Every season the yield potential of September sown cotton was compromised by deleterious weather conditions (e.g. cloud, heat waves or rainfall) highlighting the inherent limitations that have been associated with the traditional Bollgard II® mid-September to late October planting window.

August sowing does not negate the risk of wet weather at picking but compared to the traditional mid-September to late October sowing window the level of crop exposure is significantly reduced and the increased yield potential offers a sizable buffer against lint quality downgrades if they occur.

This research has been conducted in partnership with growers and consultants at a commercial scale without forsaking scientific rigour. The experiments were also fully utilised for extension purposes so that growers could experience research results in real time. The outcome has been rapid adoption of August sowing by CQ growers with 70% of the Central Highlands crop planted in August for the 2017/18 season just months after the completion of this research project.

The project also examined the pest status of symphylids a soil dwelling organism that had been considered to cause crop establishment problems in some seasons in CQ. Survey data suggests that this organism alone is an unlikely causal agent for crop establishment problems with damaged fields found to have a complex of other contributing soil pests and pathogens present.

Experiments to better understand boll rots were also conducted during the project. This research suggests that some of the causal pathogens for tight locking may gain entry to the boll during the pollination process although the development of disease is still dependent on favourable (wet) conditions during flowering and boll opening. A wide array of pathogens were identified from tight locked bolls with the abundant presence of Alternaria spp. suggesting that this group of pathogens (typically associated with leaf disease) might also be significant in the incidence of tight lock disease in CQ.

The cotton industry is a major player in Australia’s agricultural sector. It produces around 3% of the global cotton crop, delivers an average $2 billion per year in export earnings, and employs up to 10,000 workers across numerous regions. The industry comprises over 2,500 individual farms that cover over 45,000 km2 of farmland, mainly in inland NSW and Queensland with smaller areas in Victoria and Western Australia.

The cotton industry is reliant on a significant stock of natural capital that includes soil, water and biodiversity assets of the major riverine floodplains. While past management practices within the industry have depleted natural capital stocks over the past 50 years, emerging initiatives such as ‘myBMP’ seek to place the industry on a sustainable footing through improvement of on-farm practices that include better irrigation, use of chemicals, and management of native vegetation. These initiatives are being driven by a growing awareness that protection and restoration of natural ecological processes and ecosystem complexity in agricultural landscapes are important factors in the control of agricultural pests, maintenance of healthy rural landscapes, and improvement of farm profits.

Improving knowledge about natural systems in the cotton landscape will provide industry with a better evidence-base from which to set objectives and prioritise actions for natural capital enhancement via wholeof- industry management. This report presents a snapshot of key biodiversity assets across the cotton growing regions of NSW and Queensland, and uses these data to identify places in the landscape that would benefit from efforts to protect existing ecological systems or reconstruct/restore former native vegetation.

To understand an important component of natural capital in cotton growing regions, key biodiversity data were compiled across the combined extent of all cotton properties (45,070 km2) as well as the ‘cotton landscape’ (136,117 km2) which includes all cotton properties plus a 5 km buffer.

Each year, Crop Consultants Australia - with support from CRDC - conduct a qualitative survey of cotton consultants regarding their practices and attitudes, as well as those of their cotton grower clients. The resulting report provides valuable information to the Australian cotton industry regarding on-farm practices , helping to benchmark the industry's performance in a range of key areas over time. This report, published in March 2021, looks at the 2019-20 cotton growing season.

Irrigation currently uses 70% of all the world's freshwater withdrawals. Given the increasing demands for water from all other sectors of the economy, including the environment, irrigation is going to have to give up some of its water and improve its water use efficiency to produce more product with less water. This means that every litre of water made available to irrigated agriculture needs to be used productively and that any potential ‘water losses’ need to be prevented or at least minimised. Seepage/leakage losses from water distribution channels are variable but have been measured to be 3 to 24 mm/day and as high as 50 to 400 mm/day. These are significant losses that waste money and reduce crop production, but the water losses can be reduced by lining water distribution channels with clay liners, concrete liners, geomembrane and/or other ‘plastic’ liners.

Various methods are now available to identify the locations where seepage losses occur and to help quantify losses from water distribution channels. We have visited and/or held conversations with water authorities, grower organisations and growers in four different irrigation schemes around the country including Harvey Water in the south west corner of Western Australia, the Ord Irrigation Scheme in the north east of Western Australia, the Burdekin Haughton Water Supply Scheme in north Queensland and Murray Irrigation in southern New South Wales. Our aim in doing this was to learn from experiences in each of the four irrigation schemes in (i) dealing with seepage/leakage losses from water distribution channels, and (ii) to see if water managers would be interested in having access to a commercially available sprayable polymer channel liner to help reduce seepage/leakage. We also carried out a literature search and explored the web to gain an understanding of seepage/leakage losses from water distribution channels and the current channel liner products and their use. The results of this scoping study has confirmed that there is strong interest from one of the four irrigation schemes for a cost-effective commercially available fit-for- purpose sprayable channel liner for use on large regional water distribution channels. There is also interest from some of the other irrigation schemes in having access to a sprayable channel liner for use in small on-farm water distribution channels and on-farm water storages. If a cost-effective, practical, durable and fit-for-purpose sprayable polymer channel liner was developed and commercialised successfully it would have the potential to increase irrigation water availability substantially. Use of a technology like this would improve the cotton industry’s water use efficiency and yield potential by minimising seepage/leakage losses from water distribution channels.