AN ENERGY efficiency audit of the new overhead irrigation system on Adam McVeigh's Darling Downs farm in southern Queensland has set him on the path to reducing emissions and making big savings in energy costs.

The green mirid, Creontiades dilutus (Hemiptera: Miridae), is a serious pest of cotton in Australia (Adams and Pyke, 1982). Minds are sucking insects which feed preferentially on the actively growing points of young plants. The damage they inflict to the tips of pre-squaring cotton and to early squares can result in delayed maturity of the plants and a reduced yield (Bishop, 1980). Current control of the green mirid relies on early season chemical sprays. The use of chemical insecticides is disruptive to beneficial insect populations as well as being expensive and environmentally harmful. One new strategy for insect control is the use of genetic engineering to produce plants resistant to insect attack. Chemical control of Heliothis armigera has already been augmented with the use of cotton plants expressing Bacillus thuringiensis (Ali and Young, 1993). A similar strategy for control of the green mind would be a desirable alternative to chemical insecticides.

To examine the genetic similarity of cotton cultivars available in Australia, twelve cultivars of Gossypium hirsutum, together with an American Pima cotton (G. barbadense) cultivar, were subjected to genetic fingerprint analysis using the technique of RAPD-PCR 1 The study revealed that it is possible to differentiate each of the CSIRO cultivars, even though the majority of these cultivars possess greater than 90% of their genetic material in common (Figure 1 ). As would be expected from their wide pedigrees, cul ti vars such as CS 50 and DP 90, together with the G. barbadense cultivar Pima S-7. reveal much less genetic similarity. From these results we can assume that if such an analysis were extended to cultivars with unknown pedigrees, it would be possible to obtain a detailed picture of their genetic relatedness.

Fov is the causal organism of Fusarium wilt disease in cotton. This disease is of serious concern to the cotton industry in terms of potential yield loss. Existing CRDC projects in progress to identify genes associated with cotton’s response to Fov infection (CSP114C) including those genes associated with the expression of moderate resistance. Once potential genes have been identified as being associated with resistance responses, it is necessary to confirm that these genes are playing an active role in the expression of this resistance. One approach that may be used to verify the role of any particular gene in resistance is to generate transgenic plants in which the expression of this gene has been altered and to look for a change in disease resistance. This is not feasible in cotton but would be feasible in the model plant Arabidopsis thaliana, where suitable genomics tools (e.g. rapid and simple transformation, complete genome sequence, diploid plant) are available. One of the aims of this project was therefore to establish a model Arabidopsis/Fusarium oxysporum system to complement studies with cotton and Fov. We wished to know if the importance of genes detected in the cotton microarray work (CSP114C) could be assessed rapidly in Arabidopsis and if it would have been feasible to perform gene discovery work in the system for application to the cotton system. In order to achieve this we needed to set up and develop expertise in the Arabidopsis/Fusarium infection system.

The second part of the pilot project dealt with developing the tools required to undertake a study of the molecular basis of pathogenicity of Fov. This may have lead in the long term to the development of novel disease resistance strategies. In order to undertake molecular analysis of the pathogen, a transformation system for Fov is required. We wished to apply an Agrobacterium-based transformation method developed for Fusarium oxysporum pathogens of Arabidopsis to the cotton pathogen Fov. Initially we planned to introduce reporter genes into the fungus to generate transgenic strains with immediate practical use in studying Fov infection dynamics in experimental systems and in the glasshouse.

It was hoped that development of these technologies would form the basis for a further project aimed at verification of the role of genes already discovered, the discovery of novel plant genes and the elucidation of pathogenesis mechanisms in Fov.

Since the late 1980's secondary soil salinisation has been recognised as a potentially threatening problem in many of the irrigated cotton growing areas. This has been most apparent in the lower Macquarie valley and at Bourke where large earthen storage dams constructed from semipermeable soil materials have leaked. Owing to the presence of subsurface textural boundariesshallow water tables have been created in adjacent irrigated fields which have redistributed stored soluble salts within the rootzone. In Dalby and the Lockyer valley, the application of poor quality irrigation water has resulted in minorproblems with salinisation of surface soil. Fortunately, there have been no widespread occurrences of secondary soil salinisation as a result of rising water tables or the prolonged use of poor quality irrigation waters.

Integrated pest management systems for cotton are now being developed that place a greater emphasis on beneficial insects (Mensah and Harris 1994, Murray et al. 1994). The development of food sprays and the planting of lucerne strips has shown that effective populations of beneficial insects can be maintained within cotton crops (Mensah and Harris 1995). Reductions in pesticide use associated with the introduction of transgenic cotton should also increase the abundance of beneficial insects (at least those not dependent on Helicoverpa) and improve natural control (Dick 1994, Fitt 1994). However, there is considerable scope within the cotton agroecosystem to use other crops as nurseries and/or refuges for beneficial species, and/or as trap crops for Helicoverpa and other pests. Such nursery crops or refuges could be sown in strips through cotton fields, in a similar way to that proposed for lucerne, to attract beneficial species and/or trap pest species. The advantages and disadvantages of various crops in such a system have not been fully investigated. The nursery crop approach relies on there being sufficient beneficial insects within the wider cropping system to colonize the nursery crops in the first place and perhaps recolonize it during the season if pesticide application or drift eliminate populations in the nursery crop. However, we understand very little about the origin and dynamics of beneficial insect populations outside the cotton crop. Where do beneficial species originate and what happens to their populations when the cotton crops disappear? Which natural habitats or crops generate most beneficials?

Cotton growers and consultants are becoming concerned with the level of compaction in soils in the Gwydir. The feeling is that compaction is increasing due in part to the use of round bale pickers and to working the soil when it is still above the plastic level at depth. Compaction is believed to be impacting the productivity of the region. It is influencing crop growth, nutrition and water use and may be increasing water logging. Soil pits dug as part of the Gwydir Valley area wide management groups at Ashley and Telleraga in July 2013 indicated that there was a compaction on our irrigated cotton soils. Further pits dug in May 2014 confirm that soil compaction is not an isolated issue. General the cracking clay soils across the Gwydir Valley do repair themselves when they are able to have a series four or five wet and dry cycles. This project examined possible remediation techniques which may benefit the soils and concentrated on two key areas : 1. To increase the awareness and understanding of the compaction in irrigated cotton soils in the Gwydir Valley and 2. To investigate possible crop rotations and mechanical approaches which may help reduce the degree of compaction in irrigated soil. This is seen as important in helping to achieve a more resilient and competitive cotton farming system and an environmentally sustainable cotton industry.

Pest management is only one link in the cotton management chain. To produce an early crop it is essential that all links in that chain be securely welded together.

From before the first seed is planted, everything that 1s done, 1.e. selection of seed variety, to all cultural practices and 1nsect control must have one aim and that is earliness. There are three main cultural practices in this area: (1) Long fallow dryland, (2) Limited water - pre-watered and one other watering (usually after the corn has been finished watering in early February) and (3) Fully irrigated.

To the question "Can nutrition affect earliness?" the answer must be a definite Wes". Further, it will be just as important a factor as irrigation or pest management. Correct nutrition will form the basis of any attempt to produce a good early crop and without it one would be less likely to utilise other management tools in their most effective manner. Correct crop nutrition is more than just a question of what fertiliser at what rates or time, but rather an integrated approach leading to the most beneficial use of the fertiliser applied. The information contained in this paper applies to sel^-mulching black soils west of Wee Waa