Helicoverpa armigera (Hubner) and H. punctigera (Wallengren, commonly called heIiothis, have historically been the primary focus of cotton pest management in Australia (Fitt 1994; 2000). The full commercial release of second-generation Bt cottons (BOLLGARD II ), scheduled for the 2004-05 season, is set to radically change the hierarchy of key insect pests of cotton by ending the dominance of hellothis. By virtue of its highly effective built-in chemical defence resulting from stacked Bt genes, BOLLGARD II is widely expected to be much less susceptible to heIiothis damage than conventional or first-generation Bt cottons (INGARD). Central Queensland (CQ) cotton growers are among those that stand to benefit enormously from access to the new technology. Among the key benefits of the new technology are a significant reduction in insecticide use and the resulting benefit to the CQ environment and its inhabitants. However, access to new technology in the CQ region comes with a price tag that involves diligent adherence to the regions unique area-wide heIiothis management program and Bt resistance management strategy. Support for and compliance with these and other best practice options requires an understanding of the factors underwriting access to Bt cotton technology and, often, a gentle reminder of the way things used to be. The objective of this paper is to provide a historical overview of heIiothis research conducted in CQ since 1996, leading up to the current situation and the imminent release of BOLLGARD II in the region.

In modem society there has never been more emphasis placed on the accuracy and reliability of spatial information used for management of natural resources. As management decisions regarding environmental and built resources are being more closely scrutinised, so too are data used for decision making based on alternative land uses. Therefore the collection of accurate natural resource data and their processing into useful information are of utmost importance. In recognition of these requirements, the Australian Cotton Cooperative Research Centre funded (total funding: $37 million) a number of research projects since 1994 to make inventories of soil of the cotton-producing regions of Australia. The outcome of this project is a large amount of both quantitative and qualitative soil data covering much of the northwestern New South Wales and southwestern Queensland.

The Insecticide Resistance Management Strategy (IRMS) for cotton is designed to manage insecticide use, maintain the susceptibility of pest species to insecticides and to manage resistance where it already exists so that it does not become worse (Johnson and Farrell 2003). One pest, the two-spotted spider mite is renowned for rapidly developing resistance to insecticides worldwide. In order to prevent this happening in cotton a mite-specific component has been developed in the IRMS. This strategy is based around two core principles (1) use limitations, to a maximum of two applications of any pesticide group, and (2) rotation, ie. non-consecutive use of the same chemical. Monitoring is an integral part of the effective management of resistance in T. urticae in Australian cotton. Results of annual monitoring have chronicled the demise of the organophosphates and anticipated the need for newer chemistry (Herron et al. 1998; Herron et al. 2001). Here we present monitoring data for seasons 2001-2002 and 2002- 2003 and discuss implications for future resistance management of mites.

Cotton aphids are a potential problem for future cotton systems. Their abundance in different cotton seasons is strongly influenced by the availability of over-winter hosts, hence in the recent dry years they have generally riot been as much of a problem as they were in the years following the wetter winters of 1998 and 1999. Consequently, a change to wet conditions would see the potential for high aphid numbers earlier in the season again. This poses a risk to cotton for several reasons. Firstly, because the effect of aphids on the Growth and yield of cotton is poorly understood. Secondly, because aphids are vectors of Cotton Bunchy Top disease. Finally, because aphids are increasingly resistant to some of the insecticides used for their control, notably pirimicarb (carbamate) and most of the organophosphates (dimethoate, omethoate, profenofos, chiorpyrifos). Over the past three years we have completed experiments to determine if aphid populations affect cotton growth and yield. Such information can provide the basis for development of thresholds for control. However, it is also important to obtain information on aphid ecology and distribution that will help in developing more robust management strategies. For this reason we have also monitored the use of alternative hosts by aphids, their distribution within cotton field and within plants. In addition we also interested in the carry-over of resistance from one year to the next.

Irrigation is an indispensable technology used to augment agricultural production in the semi-and and arid regions. However, poor water management (eg. unsuitable location of reservoirs) can lead to the creation of perched water tables and secondary salinisation. In some irrigated areas in the northern Murray Darling Basin, point-source salinisation has occurred (Trialnaillis et. al. 2003a) whilst in others there is little or no evidence. This is because waterlogging and salinisation occur as a function of interactions between various biophysical factors such as agronomy, geology, hydrology, climate and topography. In order to determine where these problems may arise, biophysical features that are influenced by agronomic practices need to be generated. Stored in Geographic Information Systems (GIS), the interaction between biophysical data layers can be related to where salinisation occurs, and where these conditions may be met elsewhere. Recently airborne geophysical methods have been used to develop layers (eg. National Dryland Salinity Program). The start-up-cost of around $7-121ha is prohibitive. Alternatively, salinity hazard and risk maps are being produced at catchment level (e. g. State Government Agencies) using qualitative soil/geology data and land use information. The results may lead to maps of low accuracy/interpretability. A major reason for this is that weightings given to particular biophysical layers are subjective (i. e. assigned by so-called experts). In the following paper we describe the development and spatial distribution of deep drainage (DD) risk, average clay content (0-7 in) and average salt store (0-10 in) in the cotton growing districts of Trangie and Warren in the lower Macquarie valleys of central New South Wales (see Figure I). By doing this we mapped individual biophysical layers thought to contribute to the causes of water logging at a site where soil salinisation was first reported in the Trangie district in the early 1980&#39s. Critical values thought to cause salinisation were determined: a) DD risk is greater than 0.5 beneath water reservoirs; b) average clay content (0-7 in) > 38 %; and, c) average salt store (0-10 in) > 2.5 dS/in. By using GIS type analysis we mapped where these three conditions would be met and hence create salinity hazard maps associated with the construction of reservoirs. The results are consistent with areas where salinity has been experienced. The maps also indicate where best management practices developed in Trangie district could be extended.

The Silverleaf whitefly (SLW), Bemisia tabaci Biotype B is a major production constraint in many parts of the world including the USA, Israel and other parts of the Middle East. Legumes, particularly soybean, have been virtually eliminated from many production systems in Texas and Arizona where SLW is now endemic. Cotton growers in the USA (Arizona) are faced with potential losses of up to $500 million annually, directly and indirectly from SLW. SLW was first discovered in Australia in 1994 by Dr. Robin Gunning (NSW department of Agriculture). Research by CSIRO scientists has since shown that it has spread throughout much of the east coast of Queensland and is now the dominant whitefly on both cultivated and wild host plants in the northern half of Australia. SLW has since become a troublesome pest of horticulture with frequent outbreaks in the Bower/Burdekin region and other coastal regions of Queensland and New South Wales. The spread of SLW into the central Queensland (CQ) cropping areas of Emerald and the Callide and Dawson valleys presents a serious and imminent threat to field crops including sunflower, peanut, grain legumes and cotton in these areas and other cropping regions further south.

Earlier maturity in cotton would counteract increasing production costs and facilitate the expansion of cotton production into areas with shorter growing seasons. Gaining earlier maturity without some yield penalty is difficult to achieve. Ultra-narrow row (UNR) cotton, a production system with rows spaced less than 40 cm apart, has shown potential for earlier maturity than conventionality spaced cotton (1m apart), without substantial yield penalties. In practice, this earlier maturity has been difficult to achieve consistently in UNR trials in both Australia and the United States. Information on the growth and development of UNR cotton is needed to find out why. A trial in southwest NSW near Hillston compared cotton in ultra-narrow (25 cm row spacing) and conventionality spaced rows. Despite greater dry weight and fruit production in UNR earlier in the season, the competition for light and resources later in crop development negated these early benefits and did riot translate into either earlier maturity or any increase in crop yield. The structure of the UNR cotton canopy meant that light was not penetrating through the top part of the plant to bolls lower in the canopy, perhaps delaying maturity. Studies are continuing into a greater range of environments and different population densities to further understand the key physiological processes of UNR production in order to optimise the system

Previous studies of soil used for cotton production has highlighted that soil structural decline may be a potentially one of the limiting factor restricting cotton growth (CRDC report MCK IC & MCK 2C). Surface soil aggregates of soil used for cotton production will slake and/or disperse in water. The implications vary according to the scale at which this phenomenon occurs. Generally slaking is a desirable process in terms of surface soil structural regeneration, a process termed self-mulching. If slaking is excessive, resulting in aggregates < 100 pin in diameter, there is a chance that a temporary surface crust may form (Loch, 1995). Further, if the slaked aggregates disintegrate to producing sand, silt and clay, an undesirable massive structure may result. Water and air movement, root penetration and function, and seedling establishment often are affected adversely (Field, 2001). In order to identify the potential for surface soil structural decline two soil stability procedures have been identified by the industry. One of the procedures is termed the aggregate stability in water test (ASWAD, developed by Field et al. (1997), which is a diagnostic procedure used to assesses the degree of dispersion aggregates experience when immersed in water. The advantage of the test is it requires little specialised equipment, is relatively expedient making it satisfactory for routine use by land managers in the field or at home. Consequently the ASWAT procedure has been incorporated into SOILpak for cotton growers (3&#39rd edition) making it accessible to workers in the cotton industry. The other procedure identified by industry is a modified end-over-end technique. This procedure is used to assess the rate at which surface soil slakes and/or disperses. By comparing these surface soil breakdown dynamics it is possible to assess the potential for a surface crust to form.

Soil type and climate both influence the cotton plants response to soil moisture status. Soil types differ in both the amount of moisture contained and more importantly how this moisture is available to the plant. Climate, through evaporative demand, influences plants requirement for water, mainly through changing evapotranspiration rates. The combination of these two factors has a large effect on the level of plant moisture stress and consequently irrigation scheduling for cotton. Our research investigates the effect of these factors on the cotton plant in the Australian cotton industry and our aim is to refine irrigation scheduling guidelines and promote increased water use efficiency

Our research addresses three questionsI. Is soil biodiversity reduced in agricultural soil compared with undisturbed soilsΓ2. Does cropping affect which groups of fungi are present in agricultural soilsΓ3. Do microbes increase carbon stored in soilΓ