The use of carbon isotopes as a 'natural marker' of Helicoverpa has proven very useful in this regard (see below). This short paper presents some preliminary results of carbon isotope analyses that we have conducted using both H. armigera pupae collected within a range of different crops and reared to adulthood, and mating moths collected within Bt crops. The research is a follow on from a preliminary study by G. Fitt and P. Gregg (unpublished data) who first recognised the potential for using carbon isotope signatures for identifying the plant host origins of Helicoverpa moths in Australia. Others (e.g. Gould et al 2002) have used the technique to identify plant host origins for other moths overseas.

The objective of this study was to determine what if any biological activity occurred in H. armigera adults and larvae when exposed to extracts from a leguminous plant from Africa, herein referred to as Plant Y.

Black root rot (caused by Thielaviopsis basicola), is an important seedling pathogen in the cotton industry in Australia (Nehl et al. 2004). The disease develops in the early part of the season (3-5 weeks after sowing), under favourable weather conditions, especially low soil temperatures (16-20 DEGREES C). All production areas in NSW and Queensland currently have the pathogen. There are currently no practical eradication methods and prevention, by farm hygiene, is vital. The pathogen produces large quantities of thick-walled spores (chlamydospores) that persist in the soil over long periods. Movement of contaminated soil via farm machinery and vehicles has a significant contribution to transferring the pathogen within and between farms. Several leads are currently under investigation for developing better disease control, including the impact of crop rotations on spore concentration and disease, the use of novel biofumigation (green manure) crops, and the relationship between soil types and disease severity. A further avenue of research is the use of synthetic chemicals, such as acibenzolar-S-methyl (Bion, Syngenta Crop Protection), which act to induce resistance to the pathogen prior to the pathogen attacking the plant. This enhanced form of resistance is referred to as systemic acquired resistance (SAR).

Black root rot is a seedling disease caused by the soilborne fungal pathogen Thielaviopsis basicola. It is a significant threat to cotton and other crops in Australia, especially in cooler areas and seasons. The pathogen, T. basicola, produces thick walled spores that can survive in the soil for years (Figure 1). Although it was first detected in NSW in the 1980s it quickly spread by movement of the spores attached to foot-ware or machinery wheels. In just over a decade it has come to affect more than half of the cotton farms in southern Queensland and New South Wales. Regular disease surveys of cotton fields in NSW have shown an increase of incidence from 22% of fields inspected in NSW in 1995 to over 60% of farms surveyed in NSW in the 2000/2001 season and it was estimated that the incidence of black root rot in 2004 have reached 95% of the fields regularly surveyed in northern NSW (Allen and Lonergan 1997; Allen 2002; Nehl and Allen 2001

The severity of diseases caused by species of Fusarium is often increased by high rainfall and cool temperatures (Neal, 1947; Sharma and Sharma, 2003; Wang et al., 1999; Young, 1947). Wet conditions are commonly encountered early in the cotton growing season in parts of Australia. Wang et al. (1999) found that disease caused by Fov on cotton seedlings, in the glasshouse, was most severe within a temperature range of 18 - 23C and was decreased at higher temperatures, suggesting that cooler climatic conditions would favour the development of Fusarium wilt in the field. Similar temperatures are experienced in the early part of the season in Australia. If sowing can be delayed without leading to yield loss, the period of exposure of the crop to cool wet conditions that favour infection of seedlings by Fov may be decreased. We studied the impact of delayed sowing on the severity of Fusarium wilt of cotton in three seasons on a farm near Moree, Australia.

In Australia, most cotton is sown from late September to early October, when cool conditions, favourable to black root rot, usually occur. By comparing disease severity with different sowing dates and monitoring disease progress, we showed that delaying sowing can minimise the period of time that cotton is exposed to conditions favourable for development of black root rot.

My presentation is entitled "Industry Directions". I would like to share with you my thoughts and key areas of concern as identified by The Australian Cotton Industry Council. In my presentation I will also discuss a brief Industry SWOT and identify some gaps in Risk Management - how we are affected and are we properly prepared?

Fusarium oxysporum f. sp. vasinfectum (Fov) is an economically significant pathogen of cotton in Australia. Although the levels of resistance present in the new commercial cultivars have significantly improved, cotton breeders continue to look for additional sources of resistance. The native Australian Gossypium species represent an alternative source of resistance because they could have co-evolved with the indigenous Fov pathogens. However, they belong to the tertiary germplasm pool, which is the most difficult group of species from which to introgress genes into cultivated cottons. Interspecific triploid hybrids can be generated but they are sterile. The sterility barrier can be overcome using synthetic polyploids as introgression bridges, but it now clear that there is insufficient homoeologous chromosome interaction at meiosis to make these good breeding lines. A careful analysis of these lines, however, provides, an opportunity to begin to understand the genetics of fusarium wilt resistance in cotton. Fov disease bioassays on G. hirsutum X G. sturtianum BC3 multiple alien chromosome addition lines revealed that two G. sturtianum linkage groups were associated with improved Fov resistance, while two G. sturtianum linkage groups were associated with increased Fov susceptibility. This result suggests many genes are interacting in the cotton plant to determine the level of fusarium wilt resistance. To complete our understanding of the complex inheritance of resistance to the fusarium wilt disease in cotton, quantitative trait loci analyses of the segregation of fusarium wilt resistance in an elite cotton family have been undertaken. We aim to map quantitative disease resistance loci, which act additively to confer disease resistance against Fusarium wilt. By identifying QTLs for fusarium wilt resistance, we intend to identify the genes involved and mark them with molecular marker surrogates that can be used in marker assisted breeding projects to develop a new generation of better fusarium wilt resistant cultivars.

A major research effort over the last 13 years by researchers from DPI&F in collaboration with other agencies has sought to understand what strains of the pathogen are present, monitor the distribution of the pathogen and to identify new stains as they emerge. A major focus has been on the development of disease management strategies including exclusion of the pathogen and farm hygiene practices, development of varieties with higher tolerance to Fov, crop rotation options, biological control and silicon fertilisation. The aim of this paper is to summarise some of the research findings of the DPI&F on management of Fusarium wilt of cotton.

The objective of this study was to determine the genetic diversity of Fov in Australian cotton fields. This will provide information relevant to the attempt to control the disease through breeding of resistant cotton cultivars and development of improved phytosanitary strategies.