Distributed across every major cotton growing region, the Australian Cotton CRCs National Extension Network aims to enhance the returns to industry accruing from the implementation of research and development. Industry Development Officers (IDO), District Agronomists, specialist officers in the areas of Water Use Efficiency, Irrigation, integrated Pest Management (IPM) and Spray Application Technology and a National Coordinator provide a close link between industry and research. In addition to their local role, each member contributes to a national extension effort through one of the Insects, Farming Systems, Environment, Diseases SE Weeds or Water focus teams. These teams work closely with researchers and their ACGRA members to ensure that consistent messages are extended across the industry with minimal duplication of effort.

Cotton is one crop with an opportunity for a true integrated weed management strategy to be implemented. New herbicide chemistry, genetic engineering and new machinery when combined together offer the prospects of achieving a more environmental and ecologically sustainable weed management approach for the industry. This paper aims to briefly discuss three weed management issues for the cotton industry. Firstly, examining current weed management systems in the cotton industry, high-lighting some of the advantages and potential problems associated with current management strategies. Secondly, addressing weed management techniques that are likely to be adopted in the future and thirdly a discussion on the future of using manual 'chipping' in the industry.

Bacterial stunt is a disease in which soil borne bacteria colonise cotton roots and inhibit the growth and mycorrhizal development of the plant. Brown discolouration develops rapidly in the roots of stunted plants. Stunting is relatively uniform and, therefore, may only be noticeable when parts of a field are affected and parts not. Stunting tends to be more severe in heavy clay soils, even though these soils may have high levels of nutrients such as phosphorus (Nehl et al 1996a, 1996b). In some cases crop growth picks up mid-season and yields are acceptable but yield loss of up to 50% occur when cotton is severely affected. There are few options for control of bacterial stunt. Eradication of the pathogenic bacteria from soil is impractical. Permanent bed systems appear to have lifted yields, although the relative patterns of stunting across fields remain. At present the best option for control is to optimise management of the crop

Cotton aphid and two-spotted mite have the potential to cause dramatic reductions in the yield and fibre quality of cotton. Management of these pests is strongly dependent on insecticides and acaricides. Recent development of resistant in both species now threatens the sustainability of their control. This project will monitor resistance in mites and aphids to existing control options, and establish baseline resistance and cross resistance data for new chemistry. This will enable continued development of effective resistance management strategies and integration of new control options, thereby maintaining the sustainability of cotton production. This will be best achieved by pursuing an integrated approach, including monitoring, cross-resistance testing, mechanism elucidation, and the evaluation and the timely inclusion of new chemistry that is compatible with IPM. This project will monitor the resistance of mites and aphids to a wide range of current control options. For new options, biological and synthetic, a sound knowledge of the base-line (initial) resistance levels and cross resistance profiles will be developed so they can be effectively incorporated into resistance management strategies. Without this study Australia's capacity to manage these pests, and in particular our reputation as a producer of clean lint, uncontaminated with aphid honeydew, could be dramatically affected.

In recent times there has been general recognition that broad based legislation, while it must remain the cornerstone of community standards, does not fully address the needs of the community for better environmental performance. Laws can only enforce to a standard, they do not encourage performance greater than the standard. This has led to various sectors of the community putting in place Quality Assurance or Best management or Codes of Practice programs for the dual purpose of encouraging members of their sector to improve their performance above the law to a common benchmark for internal reasons and to provide a vehicle to demonstrate to other sectors of the community that they are responsive to, and share, the general increased awareness and concern with respect to environmental performance.

While many Australian cotton growing valleys had the fortune of relatively low Helicoverpa spp. activity during the 1997/98 season, this was not the universal experience. Extremely high pest activity on the Darling Downs has reinforced the concerns that our current over-reliance on insecticides for the management of Helicoverpa on cotton and grain crops is unsustainable. Just as important is the realisation that within the agro ecosystem, action must be taken to attempt to maintain Helicoverpa spp. populations at more manageable levels. While densities of up to 10 eggs per metre can be managed satisfactorily, densities of 50 or more eggs per metre pose serious difficulties, especially if activity persists at this level for several days or even weeks. Helicoverpa spp. populations fluctuate in response to various factors. Where a succession of wild or cultivated hosts are available, successive generations can develop through the spring, summer and autumn months. If progressive population increases take place for whatever reasons, the end result can be serious management difficulties. Such was the case on the Darling Downs during the 1997/98 season, where the earlier than normal appearance of substantial numbers of H armigera and their persistence at high levels throughout the season resulted in high insecticide use and some control difficulties across cotton and grain crops

Madame Chairperson, ladies and gentleman, good morning and welcome to my presentation on Profitability and Sustainability.

Thielaviopsis basicola, a phytopathogenic filamentous fungus, is the causative agent of black root rot in a variety of host plants, including the economically important crop, cotton. The method of Agrobacterium tumefaciens mediated transformation (ATMT) was chosen to investigate the molecular interactions that exist between T. basicola and cotton. ATMT has long been used to generate transgenic plants and has more recently become a popular method for random insertional mutagenesis in the transformation of filamentous fungi. Generation of a large number of reduced pathogenicity mutants using this technique will aid to elucidate the identification of key pathogenic genes providing a better understanding of the molecular interactions between T. basicola and cotton, governing the pathogenesis of black root rot.

Development of an efficient ATMT protocol, designed specifically for transforming T. basicola, required optimisation of the experimental conditions prior to, during and after transformation. Transformation efficiency was found to be dependent upon the duration and temperature of pre­ cultivation, co-cultivation and selection. The number of A. tumefaciens cells and the status of the T. basico/a cells were also found to have significant influence on the efficiency of transformation. A consistently high rate of transformation efficiency was achieved by employing the hypervirulent strain AGLI, carrying the binary vector p8Ht2, which contains the modified bacterial Hygromycin B phosphotransferase hph gene under the control of the Aspergillus nidulans trpC promoter. The

media used during co-cultivation and the method of selection also played an important role in

optimising the ATMT protocol for T. basicola. Optimal conditions of transformation led to the

production of 300-770 Hygromycin B resistant (HygR) putative transformants per I x 106 conidia of

T. basicola.

All I 0 HygR putative transformants tested remained mitotically stable, maintaining their Hygromycin B resistance after five generations on non-selective medium. Primary pathogenicity screenings indicated that three of the I 0 mitotically stable HygR putative transformants had reduced pathogenicity, showing decreased virulence towards infected cotton seedlings when compared to the WT. Vegetative growth tests of these same 10 HygR putative transformants, displayed varying growth by comparison to the WT; with six showing reduced growth and four growing at a similar rate to the WT. Colony morphology also indicated that at least seven of the HygR putative transformants differed in colour, texture, and number of chlamydospores compared to the WT.

Further genetic testing will be required to confirm that single and random insertion of the T-DNA

occurs in the T. basicola genome.

Southern blot analysis on three of the five T. basicola reduced pathogenicity mutants generated by PEG/CaC(z, revealed that in p737 and p888, more than one insertion of pGpdGFP took place at multiple loci in the fungal genome; a common occurrence when using this method of transformation. The reduced pathogenicity mutant p 16 instead had a single insert of the plasmid pGpdGFP integrated at a locus in the fungal genome, which suggests that further attempts could be made to recover the tagged pathogenicity gene from this mutant. Phenotypic analyses of all five PEG mutants, as well as 20 HygR putative ATMT transformants, indicated that T. basicola most likely has some pathogenicity genes that are similar to those found in other filamentous fungi; including genes involved in the formation of infection structures and hydrophobins, spore development and germination, regulation and biosynthesis of melanin, cuticle and cell wall degrading hydrolytic enzymes, and regulatory proteins, including transcription factors, receptors, G proteins, and enzymes.

An important requirement for successful management of Helicoverpa spp. In Australian cotton is a reliable and effective monitoring system. Timely pest management decisions must be based upon knowledge of the pest population densities with a reasonable degree of accuracy. Effective sampling for Helicoverpa spp life stages can be time consuming and onerous, and any technique which reduces the amount of time spent scouting is welcomed, provided accuracy is not compromised. Whatever sampling scheme is used must be based on an understanding of the distribution and feeding behaviour of Helicoverpa life stages and then be associated with a well validated threshold to allow management decisions. Here we briefly review sampling techniques for cotton and present our first field results aimed at assessing the validity of these techniques with INGARD cotton.

Although cotton is grown on fertile soils, commonly nutrient deficiencies become apparent due to many factors. Cotton has a high demand for many nutrients which are taken up over a period of weeks (Table I). Nutrient deficiency (or excess) can reduce crop yields. Nitrogen deficiency, for example, is easily detected, but usually by the time the deficiency is recognised and remedied, the crop has suffered some nutritional stress.