This study was carried out in afield trial on black clay soils in the Macintyre cotton growing region during a 2005/2006 cotton season and future improvements on this experiment may see significant results that will give us a better understanding of the K and B effects on cotton development, which may lead to improvements in agronomic practices.

The study will was the first stage of a process aimed at assisting the industry and its communities to manage change effectively. The industry will benefit from a better understanding of the factors affecting the economic and social condition of cotton communities, the change processes in those communities, and the means by which these factors and changes might be managed. In the discussion of possible socio-economic topics at the 'Industry and Community' meeting at UNE in April 2005, a strong consensus emerged that a necessary component of research in this area would be to select indicators that could be used to track the economic and social condition of cotton communities over the life of the CRC and beyond. Such indicators could have a variety of uses, including:helping the industry to monitor its influence on the rest of the community; helping the community to monitor its influence on the industry; helping stakeholders in both community and industry to understand the changes they were undergoing; and helping both industry and community manage these changes and interactions. The Main Project Aims were to:scope the selection of socio-economic indicators for cotton catchment communities engage stakeholders in those communities in the identification of issues relevant to the sustainability of their livelihoods engage stakeholders in the definition of indicators relevant to their communities. The report of the study will serve as a basis for addressing some of the specific questions posed in the Cotton Catchment Communities Prospectus.

Water remains a key issue for the cotton industry, with improving water use efficiency a priority. Relatively water research has focussed on the plant and its interaction with the soil and climate. Currently deficit irrigation and many different row configurations are used in the cotton industry without accurate knowledge of how these irrigation regimes affect root development. Water deficit and irrigation can influence cotton plants root systems: dryland cotton has deeper roots than fully irrigated crops and the timing of first irrigation can be used to encourage good root development. These affects are important in overall plant responses to moisture stress.

A thesis submitted in the form of two papers for fulfilment of the requirements for the degree of Bachelor (Land and Water Science) Faculty of Agriculture, Food and Natural Resources The University of Sydney

The primary purpose of DAQ 122C was to investigate alternative pest management options under central Queensland conditions with a view to supporting and expanding the role of area wide management. The project accomplished of a broad suite of research spanning the use of assassin bugs as applied biological control agents through to investigating the potential of using attract and kill technology (Magnet®) for the management of Helicoverpa and Bt resistance.

The threat of ascochyta leaf blight disease gaining a foot-hold within the CQ chickpea industry provided an impetus to re-investigate alternative legume options for spring trap cropping. Field peas (cvs Alma or Glenroy) were found to be the most effective legume for Helicoverpa trap cropping and were unique in that the majority of eggs laid on it perished due to dislodgement from the waxy foliage making it a partially self-maintaining trap crop. The adoption of field peas for spring trap cropping circumvents any problems associated with chickpea leaf blight disease.

The use of refuges to augment natural enemies in cotton was investigated, with niger identified as being attractive to the broadest range of natural enemies. However, the use of refuges was found to be a inconsistent method for augmenting natural enemies commonly associated with cotton systems. The patterns of natural enemy abundance observed in the refuge treatments were probably more closely associated with variations within the surrounding environment than any in-field modifications to vegetative biodiversity via the provision of refuges. These results suggest that the key to reliably predicting and augmenting endemic populations of natural enemies within cotton farming systems may potentially exist in developing a more refined understanding of the interactions that occur between beneficial species and the broader natural environment.

The assassin bug, Pristhesancus plagipennis was demonstrated to be an effective biological control agent for Helicoverpa and mirids in conventional cotton. Assassin bugs were found to be innately tolerant of Steward®, Admiral®, Tracer®, Regent® and Affirm®, as well as NPV and Bt biopesticides. The compatibility of these products with assassin bugs in the field is highly desirable and our experiments demonstrated that the strategic integration of these insecticides with releases of assassin bugs provided effective pest management with 50% less insecticide whilst maximising crop yield. Should assassin bugs become commercially available in the future, significant potential exists utilise them within a low spray IPM program for conventional cotton.

Population dynamic studies demonstrated that Silver Leaf Whitefly, Bemisia tabaci Biotype (B) has become a regular pest of cotton within the Dawson Valley, infesting crops each year during late November and December and peaking in abundance during February. Sampling has also determined that native Eretmocerous parasitoids have become well established with their increased abundance correlating with a reduction in regional whitefly populations on cotton. Mean parasitism rates recorded in cotton have risen from 15% in 2003 to 87% in 2005 whilst applications of Insect Growth Regulators (IGRs) for whitefly control have decreased from 40% to <5% of fields over the same period. The reduction in IGR use constitutes savings of $100 per hectare not treated. Our data suggest that it is imperative to ensure the compatibility of pest management practices with whitefly parasitoid conservation and that this consideration will continue to influence future pest management research.

DAQ122C identified the potential for using Magnet® as a regional moth busting tool for targeting last generation Helicoverpa emerging from Bollgard® fields. Such an approach could supersede the requirement for summer trap cropping as part of the CQ Bt resistance management strategy and will be the focus for future research. Refinement of the current Bt resistance management strategy is of critical importance to ensuring the prolonged viability of pesticide reducing transgenic technologies.

Best pest management practices and novel research outcomes were promoted to CQ cotton growers throughout DAQ122C via several interactive field days each season and the provision of significant technical support and input for three IPM short courses conducted in the Dawson Valley and Central Highlands regions of CQ.

Experiments to establish the response of cotton plant to soil water stress under different soil types, climatic conditions and fruiting loads have shown that (i) the response of cotton to water stress is different on different soils (eg heavy clay vs. sandy-loam) (ii) these differences can be accounted for when soil moisture content is normalised for water holding capacity, expressed as the fraction of transpirable soil water (FTSW) (iii) that climate, especially evaporative demand, can cause plant stress even when the crop has adequate soil moisture and (iv) there is no difference in soil water extraction and therefore root development by crops with different levels of fruit retention.Field experiments were run over three cotton seasons at three sites with widely different soil types around Narrabri NSW. The response of the cotton plant to moisture stress, imposed by skipping irrigations around flowering, was measured as leaf water potential using a pressure chamber. Cotton plants were found to behave in the same way to moisture stress on all soil types when the soil water holding capacity of the soil was taken in to account and expressed as a percentage or fraction of transpirable soil water (FTSW). Over the three seasons prevailing climatic conditions have a large effect on the ability of the plant to cope with a given level of soil moisture deficit. Even under low levels of soil moisture deficit, on high evaporative demand days plants often experienced stress which had an impact on yield. There are some climatic conditions under which the cotton plant is unable to take up enough moisture even from a soil profile with readily available water that the plant will become stressed no matter if more water is applied. Identifying these conditions and their management implications are the subject of ongoing research.The results of this research will provide a basis for refined irrigation management through understanding the effect of climate and soil type to reduce water stress and providing decision points for future management. This information will also be included in decision support systems through inclusion in future versions of HydroLOGIC.A separate experiment conducted over two seasons also in Narrabri showed no difference in soil moisture extraction and therefore extent of root development between crops that have high and low levels of fruit retention before cutout. High retention crops (such as BG II®) should be irrigated in a similar manner to lower retention cotton. The high level of early reproductive development does not appear to affect the below ground vegetative development of the crop. A preliminary experiment was also conducted to investigate partial rootzone drying in cotton. This showed no benefit from partial rootzone drying in terms of cotton plant stomatal control, biomass production or yield.This project has significantly improved our understanding of basic responses of cotton to soil moisture stress and how this is influenced by climate and soil type. This knowledge is vital in developing improved irrigation strategies for cotton and achieving maximum yield from applied water.

The aim of this study was to use EM imaging and .a collected by a DUALEM-421 to infer the spatial distribution of soil properties and soil particle size fractions related to .a across a prior stream channel in an irrigated cotton field in the lower Gwydir valley. EM imaging is defined by Christensen (1997) as an approximate inverse mapping of data into a model.

This project is about the development and interpretation of a range of socioeconomic indicators for a sample of case study communities where the cotton industry is a significant industry. This is one of the reports from this project and relates to the economic indicators and their interpretation.

An essential component of the plant body is the root system. It provides anchorage and support for the plant to explore its substrate, to absorb water and nutrients and to transport them above ground to the shoot system. Root systems are highly adaptive and responsive to environment flux (Stokes et al, 1996, Annals of Botany 78: 415-421).The root systems in cotton may vary in different cultivars, for example, cultivars infected with different soil-borne pathogens and cultivars with varying levels of disease resistance may show different root characteristics. The soil-borne black root rot and fusarium (Fov) wilt pathogens have been used in this project to determine whether different disease resistant lines show variations in their root architecture. The root architectures between different genotypes grown under normal conditions are also assessed in this project. More robust roots in cotton cultivars are of great agronomic significance in its potential to protect against cotton diseases without the need for chemicals. Cultivars showing robust root characteristics may be incorporated into new lines.It was found that cotton root architecture varies with genotype. Additionally, cotton cultivars respond to exposure to the pathogen Thielaviopsis basicola with some cultivars showing an increase in root branching and others showing a decrease. Furthermore, degree of root branching was seen to vary with relative resistance to the fusarium wilt pathogen

The current project was devised in the knowledge that increased sodicity and salinity of percolating water will alter the saturated conductivity of many soils, especially sodic soils. Additionally, on commencement of the project the Cotton industry had minimal data or experimentation on the scale or driving forces behind deep drainage (DD) with furrow irrigation. The project had two principal objectives: to assess the effect of increasing salinity and sodicity of irrigation water on the DD under various cotton soil types, and to utilise drainage lysimeters to directly measure DD and correlate responses in column experiments to field response.

To obtain data for the first objective, a glasshouse experiment was conducted to assess the effect on DD of changes in salinity and sodicity levels, waters being applied to large intact cores collected from each field site. For the second objective, nine drainage lysineters were installed in 3 cotton fields (3 lysimeters over each field) and data collected over a period of two cotton seasons.

There were four major sets of results. Firstly, physico-chemical analysis of the soils (to 150 cm) at each site, showed the three sites to be quite different, particularly in their clay content being on average 75%, 55%, and 45% for the Dalby, Goondiwindi and St George sites, respectively.

Secondly, the quality of the irrigation water applied at each site was quite different, in terms of its salinity, with electrical conductivity of 3358, 498 and 137 (μS/cm) for Dalby, Goondiwindi and St George, respectively.

Thirdly, the drainage lysimeters (located at 115 to 150 cm below the soil surface collected water that is deemed “lost from the cotton root-zone”and hence is deep drainage. At the Goondiwindi and St George sites in both seasons (2002-3 and 2003-4) the ranking of the amount of DD at the three in-field locations was the same, with the head ditch receiving the most DD, then the mid and the least at the tail ditch end. Long-term inundation at the head ditch rationalises these results, whereas the tail end may remain dry if irrigation siphons are stopped early. In terms of quantities of DD, the Dalby site had the greatest recorded DD; 222 mm (= 2.2 ML of water) at the head ditch end in the first season but the other two sites also recorded several instances of >90 mm of DD in one season (0.9 ML) at the head and mid field locations.

Fourthly, in a glass house experiment, irrigation with high Electrical Conductivity (EC) and low Sodium Adsorption Ratio (SAR, a measure of sodicity) water increased drainage by 4, and 2 fold in Dalby and St George soils, respectively, compared with irrigating with fresh water; however, Goondiwindi did not show any change. Irrigation with low EC and high SAR water resulted in 2, 4, and 3 fold greater drainage in Dalby, St George, and Goondiwindi soils, respectively compared to fresh water. Irrigation with high EC and high SAR water showed 5, 3, and 1.3 fold drainage increase in Dalby, St George, and Goondiwindi soils, respectively compared to fresh water. These results demonstrate an interaction between soil type (probably clay content) and water quality on deep-drainage. Water lost to deep drainage was increased more by salinity than sodicity of the irrigation water in Dalby soil (high clay content), and more by the sodicity rather than salinity of the irrigation water in St George and Goondiwindi soils.