The development of the CrylAc-resistant strains of H. armigera (BX and Is)

provides valuable models for evaluating the risks and consequences of field

populations of this pest becoming resistant to INGARD cotton.

Although the resistance ratio for the BX is strain is low in comparison to data

reported for other species, it is highly significant. H. armigera has a high natural

tolerance for Bt toxins (about 30 times that of HeIiothis virescens) and a low level

of resistance on top of this tolerance is sufficient to allow survival on glasshouse grown

transgenic cotton. Some further evaluation, involving testing of the ability

of heterozygotes to survive on INGARD cotton conducted with higher expressing

varieties and field grown plants, is required to gauge the practical significance of

this level of resistance.

As the BX strain was established from field collected insects that had survived Dr

Neil Forrester's screening assays, it was not possible to determine the frequency

of the resistance al!ele in field populations with a high degree of accuracy.

However, Dr Forrester estimated that the BX strain was established from the

survivors of perhaps 3000 field-collected insects. This suggests that one or more

insects in 3000 was carrying the resistance allele, an estimate that is of the same

order as estimates of CrylA-resistance alleles in Heliothis virescens,

Pectinophora gossypiella and Chilo suppressalis. This relatively high frequency

of resistance alleles in natural populations strongly supports the need for effective

resistance management strategies.

The very strong response of the Is strain to selection indicated that the decline in

resistance ratio for the BX strain after generation 22 was due to inbreeding

lowering the general vigour of the strain. Application of increasing selection

pressure to the Is strain showed that high resistance levels (RR=800) can be

attained by this species. The demonstration by Olsen and Daly (CSE89C) that

heterozygotes of BX and a susceptible strain have some tolerance of INGARD

cotton suggests that heterozygotes of IS and a susceptible strain could be very

damaging.

Key factors in managing transgenic Bt cottons for the future are to have an effective

resistance management strategy. An essential component of any such strategy is to

establish a resistance monitoring program. The core components of this project

address resistance monitoring as well as examine the performance of transgenic

cotton (two genes) in relation to resistance management.

Cotton production in Australia has traditionally been conducted using surface irrigation techniques on heavy clay soils. However, increasing pressures on water availability, the potential yield benefits of improved control of soil/water in the root zone, and the potential for reduced labour, fertiliser and pesticide costs has raised grower interest in alternative irrigation application techniques including large mobile irrigation machines. While less than 4% of the total Australian cotton crop is currently grown using large mobile irrigation machines, it seems likely that this proportion will increase due to existing and future pressure on water availability and environmental sustainability as well as economic and political factors. This document reports the findings from a survey of cotton growers irrigating with centre pivot or lateral move machines as well as equipment manufacturers and dealers of these machines. The survey included 25 face-to-face interviews and 6 telephone interviews with growers as well as interviews with the major manufacturers and dealers within the industry,

Quantitative Bt ELISA assays have only recently become available as a research

tool. This research will not only assist cotton breeders in identifying lines which possess

more Bt is present, but indicate where agronomic and environmental factors impact on the levels of Bt in the cotton plant. Effects of crop nutrition, time of sowing, soil condition, soil water management etc have suggested that Bt efficacy is compromised to some extent when environmental stresses are imposed on transgenic plants. Hence, productivity of some Ingard cotton crops has been substantially limited.

Various projects in the past have attempted to assess the extent to which agronomic

factors influence Bt efficacy, including Project CRC3C (Dynamics of Bt protein in Ingard

cotton: mechanisms of variable efficacy against HeIicoverpa).

The primary aim of this project was to assess agronomic factors influencing the

amount of Bt toxin measured using quantitative ELISA assays. This would enable

identification of factors in agronomic experiments which influence Bt efficacy. Sampling of experiments involving crop nutrition, plant population and growth regulators etc. may provide a reasonable guide to indicate factors that influence the efficacy of INGARD cotton andprovide a basis for recommendations to growers.

The minirhizotron system was purchased and field use commenced in January 2002.

A standard operating procedure (SOP) and protocols for using it under field conditions is being defined at present. Technical staff in the soil management program were also trained in its use. Mr. Peter Roberts, an honours student from the Department of Crop Science at

Sydney University, connnenced a project on root dynamics of irrigated cotton under different tillage systems during 2001-02.

Initial results suggest that under irrigated conditions cotton loses a major proportion of its fine root mass, and survives on its tap root. With the end of the irrigation season in March, most of the fine root mass is replaced. Minimum~tilled cotton has more roots in the furrows than intensiveIy-tilled cotton. Root/shoot ratios during early crop growth (up to December, before irrigation commences) are in the order of 4, and not around 0.2-0.4 as previously thought.

Root growth appears to take place primarily through existing soil cracks, and not through the bulk soil.

The project compared the droplet spectrum (by volume) emitted by a RAD aerial rotary atomiser mounted on a standard bracket, a RAD atomiser mounted on a extra long (XL) bracket and a Micronair AU5OOO nozzle mounted in a high velocity airstream. The influence of air speed and liquid flowrate on the droplet spectrum (by volume) emitted by a RAD aerial rotary atomiser with extra long (XL) bracket mounted in a high velocity airstream was also determined.

Cotton aphid (Aphis gossipy) and green peach aphid (Myzus persicae) are prominent pests in many of Australia's cotton regions The importance of aphid has increased in recent times due to their association with cotton bunchy top (CBT) disease. This report outlines the results of face-to-face and telephone interviews conducted with 15 consultants and seven

growers from the Lower Namoi Valley.

The initial BMP Manual focussed on pesticide use. This project aimed to explore the requirements for expanding the focus of the BMP manual, and the BMP program, to all relevant natural resource management issues. These requirements included both the development of the practical information required to address the identified natural resource issues, as well as the relationship of the BMP program to other initiatives (both Government and other agricultural industry initiatives)

The aim of the project was to provide cotton advisers and leading growers in the Hillston district (lower Lachlan Valley, NSW) with the latest information about soil assessment and management for the sustainable production of inigated cotton.

The workshop also provided an opportunity to train recently appointed Industry Development Officers,

The value of decision support packages such as SOILpak for cotton growers, third edition and NUTRlpak was emphasised.

WEEDpak synthesizes the results of extensive research on IWM in Australian cotton farming systems from research . The WEEDpak manual includes extensive reference material to help identify weeds, an important first step in IWM. WEEDpak then discusses a number of other issues involved with IWM including herbicide resistance, herbicides and their application, farm hygiene, the control of volunteer cotton, and weed control in rotation crops. Since the main thrust of IWM is management, WEEDpak , the management of specific problem weeds