Water for irrigation is the limiting resource for cotton production in Australia. While this has been recognised by the cotton industry for at least the last twenty years, the Australian Water Reform Agenda of the last five to ten years has heightened the importance of high water use efficiency. Cotton growers in New South Wales and Queensland have suffered a significant reduction in water allocation from both surface and groundwater resources since the mid 1990s. Both the research and commercial sectors of the industry have increased focus on water use efficiency issues in the last five to ten years but significantly more needs to be done. Storage and conveyance of water from government and private scheme to the farm gate, storage and conveyance on-farm, application of irrigation and the return and storage of tailwater all need to minimise losses. Fortunately with defined water allocation security, improvements in efficiency should result in increased production per megalitre for the irrigator along with improved environmental performance

Groundwater, under the right conditions can be of benefit to plants. For example, cotton can derive substantial water from groundwater at depths of around 2.6m (Wanender et al 1979). Excessive exposure to groundwater however can be detrimental. It has been shown that yield can be reduced by as much as 60% in the presence of a ground water that rises from around 3 in to less than 1m (Kahlown and Azam 2002). This occurs by either a) extending the period for which the crop root zone is saturated after irrigation or b) soil remains permanently saturated in the root zone. The depth to groundwater is primarily a function of the environmental and geological setting in which the area is located. However land management practices also have varying degrees of influence on groundwater depth.

Resistance in the cotton aphid (Aphis gossypii) is a major new threat to Australian cotton production (Herron et al. 2001). Insecticide monitoring underpins the management of resistant populations and collections of aphids are made from cotton fields, weeds farm gardens and residential backyards. These are tested against a range of the control options allowing us to identify emerging resistance problems as well as keeping track of existing problems. This information then contributes to the development of the aphid component of the Insecticide Resistance Management Strategy (IRMS) for cotton. Management is underpinned by rotation between insecticide groups and restriction in the number of applications of product from any one insecticide group. At present, there are five chemical groups to use in rotation against A. gossypii. In the current insecticide groupings the carbamate aldicarb is in the same resistance management group with pinmicarb and the organophosphates, due to likely cross resistance between these insecticides which fall into the IA and IB Groups. However, there is evidence from testing of resistant aphid strains that cross-resistance within the carbamates and organophosphates cannot be assumed. Hence, aphids that are resistant to pinmicarb or organophosphates may be susceptible to aldicarb or carbosulfan and this would change resistance management options. It was decided to investigate biochemically the potential for cross resistance between these two carbamates and other members of Group IA and IB. It was hoped to be able to separate aidicarb and carbosulfan into their own separate group for resistance management in order to give the growers more flexible control options. Here we report the results of the 2002-2003 and 2003-2004 season&#39s research on aphids and outline the practical implication of those findings for resistance management

Fusarium wilt is an economically important disease of cotton in Australia. Disease occurs at the intersection of pathogen, plant, and environment (Figure I). In the case of Fusarium wilt, the disease can only occur when cotton (the plant), infected by the soil-borne fungus Fusarium oxysporum vasinfectum (Fov) (the pathogen), experiences environmental conditions that favour the pathogen above the plant. Current control measures are by and large focussed on limiting the spread of the pathogen, and developing new cotton varieties with increased resistance to the disease

Soil health has been defined as &quote; the capacity of soil to function as a vital living system, within ecosystem and land-use boundaries, to sustain plant and animal productivity, maintain or enhance water and air quality, and promote plant and animal health&quote; (Doran and Zeiss 2000). However, the microorganisms within soil ecosystems clearly did not evolve with the specific purpose of supporting and sustaining the repetitive monocultures of modem agriculture

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.