Many researchers are involved in the evaluation of rotation cropping in several cropping systems experiments being conducted throughout the cotton production area. As well, many growers have been testing various rotation systems and are providing practical and proven information on the positive and negative aspects of these systems.

The Australian cotton industry is heavily dependent on the use of chemical insecticides and herbicides. The off-farm movement of these pesticides has created a number of &quote;environmental&quote; issues for the industry. The major ones are related to: the presence of pesticides in the riverine environment; the contamination of pasture and fodder crops leading to residues in livestock, particularly related to the use of Helix' (chlorfluazuron) and endosulfan; community health concerns related to droplet drift and odour.

The DLWC (Department of Land and Water Conservation) has operated the Central and North West Regions Water Quality Program for the past 5 seasons in the Namoi,Gwydir, Macquarie and Border Rivers catchments. The program has covered 4 main areas of study: pesticides, nutrients, biological monitoring and trace metals and their relationship to the growing of irrigated cotton (Cooper, 1995).

Biopesticides based on Heliothis nuclear polyhedrosis virus (NPV), one of the Baculovims group, are notable for their potency, specificity and safety. The virus constitutes a natural mortality factor in Heliothis populations on cotton (Wilson and Greenup, 1977) and other crops. It has evolved to produce vast amounts of infectious virus per infected insect. This can be exploited by laboratory mass production of the virus, and dissemination by the grower using conventional spray equipment. This paper is designed to give background to reports on &quote;Gemstar&quote; trials during the past two seasons. A brief history of its development as an insecticide in Australia is given in Table I.

With the imminent release of cotton varieties expressing the n\IGARD gene to control Helicoverpa the time has come to consider in detail the elements of the proposed resistance management plan for transgenic cotton. The characteristics and value of cotton varieties with INGARD and the critical need for a pre-emptive resistance strategy has been discussed widely over the past few years' Through collaboration of numerous entomologists and industry the components of a strategy have been identified and researched and details of the resistance strategy for 1996-97 have been finalised by the TMS (Transgenic and insect Management Strategy) Committee with input from researchers, growers, consultants and industry partners. Details have been widely publicised (Fitt 1996, Forrester, this proceedings). The strategy focuses squarely on Heliothis armigera as the pest most likely to evolve resistance to INGARD varieties, just as it has to conventional chemicals. Of the four man components (planting window, refuges, overwinter cultivation to destroy pupae and late season Helicoverpa control), the concept of providing refuges to assist resistance management is perhaps the most novel aspect of the whole strategy, and the most critical component. It is also likely to be the most challenging aspect for growers and the most difficult to implement effectively. Here I will briefly explain the concept of a refuge, why we need them, precisely what they are, how they work and what they will mean for growers.

ACF simply contends that far too much water has been taken from the Murray Darling for irrigation and that insufficient water is left to manage in ways which meet the ecological needs of the rivers and their floodplains, wetlands and billabongs . In a nutshell, environmental flows means water which is allowed to flow through the system in ways which best mimic natural flow regime, thereby meeting the needsof native fish, invertebrates, waterbirds and plants.

The introduction of transgenic cotton expressing the CrylAc insecticidal crystal protein from Bacillus thuringiensis (Bt) is expected to provide the basis for pest management in cotton in the near future and to reduce the usage of pesticides in the industry. However the potential for over-reliance on Bt-cotton to result in the development of resistance to Bt by Helicoverpa armigera has been identified (Edge, 1994). Recognising that his resistance would undermine the basis for pest management the cotton industry has devoted resources to addressing the problem. Experience with resistance to synthetic chemical insecticides has shown that there are options for managing resistance. One of the major options being examined is the provision of alternative means of control that will complement the Bt cotton. Among these alternatives is the identification of new insecticidal crystal proteins from Bt. Over the past four years an additional 35 Bt insecticidal crystal proteins have been recorded, demonstrating that the diversity of these insecticidal toxins is much greater than previously recognised. We have taken advantage of new molecular technologies to search for new insecticidal crystal proteins that can be used to complement CrylAc in a resistance management program.

Crop monoculture frequently causes a build up of weeds, diseases, insects and soil fertility problems. Furthermore continuous cotton production in the Macquarie Valley often causes soil compaction leading to poor crop growth and yields. While cotton growers in the Macquarie Valley have shown an interest in using rotations to minimise degradation of the crop environment, information on the merits of different rotations is sparse. This experiment was set up to provide such data.

Controlling heliothine caterpillars presents an ever greater challenge for the Australian cotton industry. The bollworm, Helicoverpa armigera, creates especial problems by evolving resistance to most major chemical insecticides. Chemical insecticides are furthermore associated with environmental dangers and increased production costs due to the need to overcome resistance.

Spider mites are world-wide pests of a variety of crops. They are important pests of cotton as they can reduce plant vigour which leads to reduced yield (up to 90%), inferior fibre and inferior seed quality (Wilson, 1993); control of spider mites is expensive and they are able to develop resistance to miticides. The two spotted spider mite comprises 99% of cotton mite pests in Australia.