Increased pressures are being placed on irrigators in Australia to maximise their water use efficiency. This has in turn highlighted the need for more focused research and extension on water management. The HydroLOGIC irrigation management system has been developed to provide information for irrigation decisions. The system provides a range of information to assist with the effective and timely application of irrigations for furrow irrigated cotton crops. Uniquely, the software has the ability to evaluate the consequences of different irrigation strategies on daily crop growth, yield and water use, using a range of simple plant and soil moisture measurements. HydroLOGIC especially offers opportunities for optimising irrigation management in limited water situations, where understanding the consequence of different irrigation strategies become even more important to productivity. Field experiments conducted dunno the 2002-03 cotton growing season demonstrated that HydroLOGIC could achieve above average yields and water use efficiency (Richards and Bange, 2003). This paper presents the results of a HydroLOGIC experiment in 2003-04, which aims to further demonstrate the &#39value&#39 of HydroLOGIC in improving water use efficiency

Choosing the best time of sowing in a particular region can often be difficult, as it is a decision that must strike a balance between sowing too early and enduring problems associated with cold weather or sowing too late and losing potential yield. This paper summarises a field experiment conducted at in Hillston during the 2002/03 season that explored the impact of sowing time and temperature on growth and development of cotton of two varieties (Sicala 40i and Siokra V-161) differing in their maturity and a Pima cotton variety (S-7). In this particular year the early and late sowing considerably reduced yield. Yield was reduced through a lower bon set and small boll size in the early sowing and poor ginout % in the late sowing. A sowing in late October maximised yield and allowed the crop to avoid the problems with cold temperatures, promote early vigour, and maximise season length thus allowing bolls and fibre to develop. The use of Sicala 40i an earlier maturing variety also improved yield by being able to set its bolls earlier and allow fibre to develop to more optimal conditions. Sicala 40i also offset the effects of the late sowing; highlighting the opportunity to use earlier varieties when sowing is delayed. Information collected from the study will contribute to an overall initiative in attempting to understand cotton&#39s response to temperature to further improve recommendations for all cotton growing regions

Growers need to monitor soil and plant nutrient status, on a field-by field basis in order to manage soil fertility and avoid nutritional stress to their cotton crops. By regular soil and plant tissue testing, they can build a substantial bank of data to assist in managing soil fertility and planning a fertiliser program where this is required. Only in this way will growers be able to identify soil problems (eg high pH, low organic matter, high sodicity (ESP) salinity (EC) or chloride) that can limit production. Similarly, regular analysis of leaf blades can help identify nutrient imbalances, deficiencies and toxicities in a more precise way than soil testing

Fusarium oxysporum f. sp. Vasinfectum (Fov) is considered the most destructive pathogen of cotton in Australia. In this study, BC3 progenies of chromosome addition lines between G. sturtianum (C genome), an Australian wild Gossypium species shown to be resistant to fusarium wilt, and G. hirsutum were genetically characterised to determine the number and identity of the G. sturtianum chromosomes in 47 G. hirsutum X G. sturtianum chromosome addition families. The 47 families were challenged with Fov (VCG 11) in glasshouse trials using root-dripping inoculations to determine their levels of fusarium wilt resistance. Overall, 20 of the BC3 families showed enhaced fusarium wilt resistance relative to their G. hirsutum parent. Logistic regression nominated five G. sturtianum linkage groups as having significant effect in a G. hirsutum background. Two linkage groups were associated with increased susceptibility.

Typically the fungus Thielaviopsis basicola, the casual organism for black root rot, is generally considered to be widespread in both cultivated and uncultivated soils; surveys were conducted in the catchments surrounding cotton properties to determine if this was the case for Australia. Knowledge of the origin and distribution of soilborne diseases can make significant impacts on both the choice and effectiveness of control measures implemented. If T. basicola had been endemic as suggested by overseas studies, then the lack of commercially effective control measures would Give little hope for control of the disease in cotton in the near future. As it stands this research has shown that T. basicolo only occasionally occurs (in highly disturbed sites) outside of cultivated cotton land, meaning that there is potential to controlthe spread of disease to unaffected farms and fields through the implementation of appropriate farm hygiene measures.

Bollgard II is simply cotton with better control of Helicoverpa and the same principles of management apply to Bollgard II as for conventional cotton. This paper, highlights a few specific issues to consider for optimum Bollgard II management. Bollgard II cotton contains two different (Monsanto) Bt genes which provide control of Helicoverpa. Our eight years of Ingard were practice for what is to follow. The better efficacy of Bollgard II compared with Ingard is important for Helicoverpa control, but the prime objective is to have better Helicoverpa resistance management with two Bt genes. This change now allows a far greater proportion of Bt cotton.

The Australian cotton industry has developed high yielding and high quality fibre

production systems and attributes a significant contribution of this achievement to highly innovative breeding programs, specifically focused on the production of premium quality lint for the export market. Breeding programs have recently shifted attention to the development of new germplasm with superior stress tolerance to minimise yield losses attributed to adverse environmental conditions and inputs such as irrigation, fertilisers and pesticides. Various contributors to yield, such as physiology, biochemistry and gene expression have been implemented as screening tools for tolerance to high temperatures under growth cabinet and laboratory conditions but there has been little extension of these mechanisms to field based systems.

This study evaluates tools for the identification of specific genotypic thermotolerance under field conditions using a multi-level ‘top down’ approach from crop to gene level. Field experiments were conducted in seasons 1 (2006) and 3 (2007) at Narrabri (Australia) and season 2 (2006) in Texas (The United States of America) and were supplemented by growth cabinet experiments to quantify cultivar differences in yield, physiology, biochemical function and gene expression under high temperatures. Whole plants were subjected to high temperatures in the field through the construction of Solarweave® tents and in the growth cabinet at a temperature of 42 oC. The effectiveness of these methods was then evaluated to establish a rapid and reliable screening tool for genotype specific thermotolerance that could potentially improve the efficiency of breeding programs and aid the development to high yielding cultivars for hot growing regions.

iv

Cotton cultivars Sicot 53 and Sicala 45 were evaluated for thermotolerance using crop level measurements (yield and fibre quality) and whole plant measurements (fruit retention) to determine the efficacy of these measurements as screening tools for thermotolerance under field conditions. Sicot 53 was selected as a relatively thermotolerant cultivar whereas Sicala 45 was selected as a cultivar with a lower relative thermotolerance and this assumption was made on the basis of yield in hot and cool

environments under the CSIRO Australian cotton breeding program. Yield and fruit retention were lower under tents compared with ambient conditions in all 3 seasons. Yield and fruit retention were highly correlated in season 1 and were higher for Sicot 53 compared to Sicala 45 suggesting that fruit retention is a primary limitation to yield in a hot season. Thus yield and fruit retention are good indicators of thermotolerance in a hot season. Temperature treatment and cultivar differences were determined for fibre quality in seasons 1 and 3; however, quality exceeded the industry minimum thereby indicating that fibre quality is not a good determinant of thermotolerance.

In recent years mirids and stinkbugs have emerged as important sucking pests in cotton. While stinkbugs are causing damage to bolls, mirids are causing damage to seedlings, squares and bolls. With the increasing adoption of Bollgard II and IPM approaches the use of broad-spectrum chemicals to kill Helicoverpa has been reduced and as a result mirids and stinkbugs are building to levels causing damage to bolls later in crop growth stages. Studies on stinkbugs by Dr Moazzem Khan revealed that green vegetable bug (GVB) caused significant boll damage and yield loss. A preliminary study by Dr Khan on mirids revealed that high mirid numbers at later growth stages also caused significant boll damage and that damage caused by mirids and GVB were similar. Mirids and stinkbugs therefore demand greater attention in order to minimise losses caused by these pests and to develop IPM strategies against these pests to enhance gains in IPM that have been made with Bt-transgenic cotton. Progress in this area of research will maintain sustainability and profitability of the Australian cotton industry.

Mirid damage at early growth stages of cotton (up to squaring stage) has been studied in detail by Dr Khan. He found that all ages of mirids cause damage to young plants and damage by mirid nymphs is cumulative. Maximum damage occurs when the insect reaches the 4th and 5th nymphal stages. He also found that mirid feeding causes shedding of small and medium squares, and damaged large squares develop as ‘parrot beak’ bolls. Detailed studies at the boll stage, such as which stage of mirids is most damaging or which age boll is most vulnerable to feeding, is lacking. This information is a prerequisite to developing an IPM strategy for the pest in later crop growth stages. Understanding population change of the pest over time in relation to crop development is an important aspect for developing management strategies for the pest which is lacking for mirids in BollgardII.

Predators and parasitoids are integral components of any IPM system and play an important part in regulating pest populations. Some generalist predators such as ants, spiders, damsel bugs and assassin bugs are known to predate on mirids. Nothing is known about parasitoids of mirids. Since green mirid (GM), Creontiades dilutus, is indigenous to Australia it is likely that we have one or more parasitoids of this mirid in Australia, but that possibility has not been investigated yet.

The impact of the GVB adult parasitoid, Trichopoda giacomelli, has been studied by Dr Khan who found that the fly is established in the released areas and continues to spread. However, to get wider and greater impact, the fly should be released in new locations across the valleys.

The insecticides registered for mirids and stinkbugs are mostly non-selective and are extremely disruptive to a wide range of beneficial insects. Use of these insecticides at stage I and II will minimise the impact of existing IPM programs. Therefore less disruptive control tactics including soft chemicals for mirids and stinkbugs are necessary.

As with soft chemicals, salt mixtures, biopesticides based on fungal pathogens and attractants based on plant volatiles may be useful tools in managing mirids and stinkbugs with less or no disruption. Dr Khan has investigated salt mixture against mirids and GVB. While salt mixtures are quite effective and less disruptive, they are quite chemical specific. Not all chemicals mixed with salt will give the desired benefit. Therefore further investigation is needed to identify those chemicals that are effective with salt mixture against mirids and

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GVB. Dr Caroline Hauxwell of DPI&F is working on fungal pathogen-based biopesticides against mirids and GVB and Drs Peter Gregg and Alice Del Socorro of Australian Cotton CRC are working on plant volatile-based attractants against mirids. Depending on their findings, inclusion of fungal-based biopestcides and plant volatile-based attractants in developing a management system against mirids and stinkbugs in cotton could be an important component of an IPM approach.

Final Report - Identification of the Glass Transition Behaviour of Australian Cotton

Project Summaries from Postgraduate Visit

McKinnon, Buchanan, Delaney, Dodd, Humphries, Ivkovic, Lightfoot, Lowor, Machado, Najar, Speirs, Vanags, Werth, Whiffen and White