Fusarium wilt is a destructive disease of cotton which occurs in many cotton growing areas of the world, including; south-eastern USA, Egypt, Tanzania and China. It is caused by the soil inhabiting Fusarium oxysporum f.sp vasinfectum (Fov) (Hillocks, 1992) The first confirmed record of the disease in Australia was from wilted cotton collected from the Brookstead/Cecil Plains area in the Darling Downs of Queensland, in March 1993 (Kochman, 1995). Fusarium wilt has since been recorded in many commercial cotton crops on the Downs and in isolated locations at Mungindi, Boggabilla, Goondiwindi and Moree. More recently, the disease was confirmed in wilting plants in the Theodore and Miles areas of Queensland. To date, Fusarium wilt has not been recorded in the Emerald or St George areas of Queensland or cotton production areas in the Namoi and Macquarie Valleys of New South Wales

In a cool, wet season when conditions are favourable for the Verticillium dahliae fungal pathogen, Verticillium wilt disease can cost the Australian cotton industry millions of dollars in lost production. The susceptibility of cotton plants to Verticillium wilt does however vary between cotton species and cultivars (Ramsay et al, 1996), and breeders have attempted to select cotton germplasm with increased resistance to the disease. True resistance can be found in cultivars of Gossypium barbadense, such as the American cultivar Pima S-7, whereas cultivars of Gossypium hirsutum at their best only display tolerance to the disease, restricting the development of disease symptoms and allowing the production of a reasonable crop. Plant breeders from the CSIRO have now developed several G. hirsutum cultivars with increased tolerance to Verticillium wilt such as Sicala V-I, Sicala V-2 and Siokra V-15

Many of Australia's broadacre crops have or will have herbicide tolerance traits added in the future. Cotton, canola, clover and wheat are just a few of the crops that are either being conventionality bred or genetically modified to tolerate both new and old herbicides. Cotton currently has Roundup Ready@ technology with the possibility of other herbicide traits being introduced in the future, however, we need to mindful of the entire farming system and other rotation crops with similar traits being introduced. This is an important period where researchers, regulators, utilisers of the technology and consumers must communicate with each other in a timely manner where and how this technology should be utilised. In the case of cotton there are a large number of potential advantages but an equally large number of management considerations including, herbicide resistance, management of volunteers and herbicide application issues. This presentation attempts to cover some of the important considerations for cotton growers utilising herbicide tolerant cotton

It is necessary to research multiple stresses on cotton as plants are generally exposed to many stresses in the field, and interactions between them are largely unpredictable. We studied the effects of spider mite damage and water stress on cotton and determined whether cotton plants could compensate for these stresses. Dryland cotton was more resilient to mite stress than irrigated cotton. Neither dryland nor irrigated plants compensated for mite damage, except under severe mite stress when lower undamaged leaves were able to increase photosynthesis relative to uninfested / healthy plants due to faster senescence in upper leaves and consequent increased light levels.

With the advancement in production of monoclonal antibodies (MAbs) that are species specific the use of serological assay as a tool for assessing natural enemies has increased during the last decade (Greenstone 1996). Serological assay has been used widely overseas to estimate the potential of predators as biological control agents. It offers advantages over other predator assessment trials in that it provides a method of quickly screening a complex of predators and can be utilised to determine the stage of prey being consumed as well as the species of prey consumed. Furthermore, it offers a means of establishing when (at what time of year) predators are feeding on target prey. If high numbers of predators are found to consume target prey at certain times of a growing season the need for chemical control may be reduced at those times. This may aid in resistance management strategies.

Information on the likely tinting of Autumn diapause induction in Helicoverpa is useful for growers planning to cultivate cotton stubble for &quote;pupae busting&quote;. Cultivation to control pupae is mandatory for INGARD cotton, and it is recommended for conventional cotton as part of the Australian Insecticide Resistance Management Strategy (Forrester and Bird 1996). The benefits of controlling H. armigera pupae in this way have been extensively published within the cotton industry (Slack-Smith et al 1997, Fitt et al 1993, Wilson 1993, Murray and Titmarsh 1990).

Transgenic plants are rapidly dominating World agriculture and already the produce from millions of acres of transgenic insect and herbicide tolerant cotton, corn, soybean and canola being traded around the World, predominantly originating from the U. S. . By the end of the decade there will be few broad acre crops whose management would not have been changed uralterably by this new technology. The experiences from these early transgenic crops are in general good, providing good value to the farmer, but sporadic reports of poor performance of the transgenic traits and of variable performance of transgenic plants between different regions, suggest that we do not yet know enough about how genes function plants to perfectly predict the behaviour of transgenes under field conditions.

This project was designed to support the deployment and continued use of transgenic (INGARD) cotton in the Australian cotton industry. To maximise the efficacy and useful lifespan of transgenic cotton we need to monitor the production of the toxin from Bacillus thuringiensis (Bt) in cotton plants throughout the growing season. Transgenic cotton contains a gene which encodes for the production of an insecticidal crystal protein (referred to as the &quote;toxin&quote;) which is highly toxic to Iepidopteran species including Helicoverpa, a major pest in the Australian cotton industry. These plants have been shown to successfully produce the toxin, but field studies indicated that the efficacy of plants was reduced later in the season (Fitt et al 1994). The cause of this reduced efficacy was not understood, although it is possible that production of the toxin is influenced by plant age or reproductive stage, and/or by a variety of environmental factors. Also, to ensure that resistance management strategies designed for use with transgenic cotton are successful, we need to assess the exposure of insects to the toxin.

The past growing season (1997/98) was the second commercial year of INGARD cotton varieties with some 60,000 ha planted across all growing regions. In the first two seasons of commercial use INGARD varieties have reduced pesticide use by 50-60% and achieved similar or better yields to conventional varieties. This represents a significant step forward in reducing pesticide use in the cotton industry. There have been several reports from CRDC and Monsanto regarding the performance of INGARD crops in relation to pesticide use and economic value to growers and I don't intend covering these issues here. Obviously the bottom line when it comes to INGARD performance is efficacy, an issue which is amenable to research. To provide most value and ease of management, transgenic cotton crops need to provide consistent and hopefully high capacity to kill the target pests quickly ie. high efficacy. Early in development of transgenic cottons the expectation was that expression of the Bt protein would be consistent throughout growth of the crop and consequently that control of the target pests would be provided almost season long. The Cry1Ac gene is driven by a promoter which gives constitutive expression in all tissues in the plant, although there are significant differences between plant structures in the level of Bt protein production. However, from the very first year of small scale field trials it soon became evident that efficacy of leaves and reproductive tissues declined during plant growth and that some larvae were able to survive beyond first instar. It was not until lNGARD crops were grown on a commercial scale that the magnitude of these changes, and the variability which can occur between crops in different fields, farms and regions became fully apparent.

Organophosphate insecticides are valuable insecticides used to control Helicoverpa armigera on cotton in Australia. Organophosphates most commonly used for Helicoverpa spp. control, are profenofos, methyl parathion and chiorpyrifos. However, there is an emerging organophosphate resistance threat in Australian H. armigera, which is compounded by cross resistance between profenofos and methyl parathion. An insensitive acetylcholinesterase has been identified as the common resistance mechanism. No resistance to chlorpyrifos has been detected and acetylcholinesterase remains fully sensitive to chlorpyrifos and its oxon