Bollgard II is simply cotton with better control of Helicoverpa and the same principles of management apply to Bollgard II as for conventional cotton. This paper, highlights a few specific issues to consider for optimum Bollgard II management. Bollgard II cotton contains two different (Monsanto) Bt genes which provide control of Helicoverpa. Our eight years of Ingard were practice for what is to follow. The better efficacy of Bollgard II compared with Ingard is important for Helicoverpa control, but the prime objective is to have better Helicoverpa resistance management with two Bt genes. This change now allows a far greater proportion of Bt cotton.

The Australian cotton industry has developed high yielding and high quality fibre

production systems and attributes a significant contribution of this achievement to highly innovative breeding programs, specifically focused on the production of premium quality lint for the export market. Breeding programs have recently shifted attention to the development of new germplasm with superior stress tolerance to minimise yield losses attributed to adverse environmental conditions and inputs such as irrigation, fertilisers and pesticides. Various contributors to yield, such as physiology, biochemistry and gene expression have been implemented as screening tools for tolerance to high temperatures under growth cabinet and laboratory conditions but there has been little extension of these mechanisms to field based systems.

This study evaluates tools for the identification of specific genotypic thermotolerance under field conditions using a multi-level ‘top down’ approach from crop to gene level. Field experiments were conducted in seasons 1 (2006) and 3 (2007) at Narrabri (Australia) and season 2 (2006) in Texas (The United States of America) and were supplemented by growth cabinet experiments to quantify cultivar differences in yield, physiology, biochemical function and gene expression under high temperatures. Whole plants were subjected to high temperatures in the field through the construction of Solarweave® tents and in the growth cabinet at a temperature of 42 oC. The effectiveness of these methods was then evaluated to establish a rapid and reliable screening tool for genotype specific thermotolerance that could potentially improve the efficiency of breeding programs and aid the development to high yielding cultivars for hot growing regions.

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Cotton cultivars Sicot 53 and Sicala 45 were evaluated for thermotolerance using crop level measurements (yield and fibre quality) and whole plant measurements (fruit retention) to determine the efficacy of these measurements as screening tools for thermotolerance under field conditions. Sicot 53 was selected as a relatively thermotolerant cultivar whereas Sicala 45 was selected as a cultivar with a lower relative thermotolerance and this assumption was made on the basis of yield in hot and cool

environments under the CSIRO Australian cotton breeding program. Yield and fruit retention were lower under tents compared with ambient conditions in all 3 seasons. Yield and fruit retention were highly correlated in season 1 and were higher for Sicot 53 compared to Sicala 45 suggesting that fruit retention is a primary limitation to yield in a hot season. Thus yield and fruit retention are good indicators of thermotolerance in a hot season. Temperature treatment and cultivar differences were determined for fibre quality in seasons 1 and 3; however, quality exceeded the industry minimum thereby indicating that fibre quality is not a good determinant of thermotolerance.

In recent years mirids and stinkbugs have emerged as important sucking pests in cotton. While stinkbugs are causing damage to bolls, mirids are causing damage to seedlings, squares and bolls. With the increasing adoption of Bollgard II and IPM approaches the use of broad-spectrum chemicals to kill Helicoverpa has been reduced and as a result mirids and stinkbugs are building to levels causing damage to bolls later in crop growth stages. Studies on stinkbugs by Dr Moazzem Khan revealed that green vegetable bug (GVB) caused significant boll damage and yield loss. A preliminary study by Dr Khan on mirids revealed that high mirid numbers at later growth stages also caused significant boll damage and that damage caused by mirids and GVB were similar. Mirids and stinkbugs therefore demand greater attention in order to minimise losses caused by these pests and to develop IPM strategies against these pests to enhance gains in IPM that have been made with Bt-transgenic cotton. Progress in this area of research will maintain sustainability and profitability of the Australian cotton industry.

Mirid damage at early growth stages of cotton (up to squaring stage) has been studied in detail by Dr Khan. He found that all ages of mirids cause damage to young plants and damage by mirid nymphs is cumulative. Maximum damage occurs when the insect reaches the 4th and 5th nymphal stages. He also found that mirid feeding causes shedding of small and medium squares, and damaged large squares develop as ‘parrot beak’ bolls. Detailed studies at the boll stage, such as which stage of mirids is most damaging or which age boll is most vulnerable to feeding, is lacking. This information is a prerequisite to developing an IPM strategy for the pest in later crop growth stages. Understanding population change of the pest over time in relation to crop development is an important aspect for developing management strategies for the pest which is lacking for mirids in BollgardII.

Predators and parasitoids are integral components of any IPM system and play an important part in regulating pest populations. Some generalist predators such as ants, spiders, damsel bugs and assassin bugs are known to predate on mirids. Nothing is known about parasitoids of mirids. Since green mirid (GM), Creontiades dilutus, is indigenous to Australia it is likely that we have one or more parasitoids of this mirid in Australia, but that possibility has not been investigated yet.

The impact of the GVB adult parasitoid, Trichopoda giacomelli, has been studied by Dr Khan who found that the fly is established in the released areas and continues to spread. However, to get wider and greater impact, the fly should be released in new locations across the valleys.

The insecticides registered for mirids and stinkbugs are mostly non-selective and are extremely disruptive to a wide range of beneficial insects. Use of these insecticides at stage I and II will minimise the impact of existing IPM programs. Therefore less disruptive control tactics including soft chemicals for mirids and stinkbugs are necessary.

As with soft chemicals, salt mixtures, biopesticides based on fungal pathogens and attractants based on plant volatiles may be useful tools in managing mirids and stinkbugs with less or no disruption. Dr Khan has investigated salt mixture against mirids and GVB. While salt mixtures are quite effective and less disruptive, they are quite chemical specific. Not all chemicals mixed with salt will give the desired benefit. Therefore further investigation is needed to identify those chemicals that are effective with salt mixture against mirids and

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GVB. Dr Caroline Hauxwell of DPI&F is working on fungal pathogen-based biopesticides against mirids and GVB and Drs Peter Gregg and Alice Del Socorro of Australian Cotton CRC are working on plant volatile-based attractants against mirids. Depending on their findings, inclusion of fungal-based biopestcides and plant volatile-based attractants in developing a management system against mirids and stinkbugs in cotton could be an important component of an IPM approach.

Final Report - Identification of the Glass Transition Behaviour of Australian Cotton

Project Summaries from Postgraduate Visit

McKinnon, Buchanan, Delaney, Dodd, Humphries, Ivkovic, Lightfoot, Lowor, Machado, Najar, Speirs, Vanags, Werth, Whiffen and White

At a July 2004 meeting of the CHCG&IA Research and Technical Subcommittee it was resolved that DPI&F research staff develop a strategy to meet the regional R&D needs of the Emerald area, as identified in a discussion paper by Mr. Hamish Millar.

Following discussions with local industry, staff and researchers from the Cotton CRC (Mr. Guy Roth, Drs. Greg constable and Ian Rochester), CSD (Mr. John Marshall) and other QDPI staff, general agreement was reached that a practical way of addressing the regional R&D needs, as identified above, is to begin with a preliminary assessment of cotton phenology and yield response in the form of a one-season pilot planting-time trial.

Cotton R&D Corporation funds for the project entitled ‘Operational Costs for Cotton Experiments’ were used to fund cotton experimental trials at the Australian Cotton Research Institute (ACRI). The management of cotton growing for cotton trial experimentation is dependent on the aims of the specific trial. However cotton growing at ACRI is undertaken to industry standards with the intention of maintaining the long-term productive capacity of the land. The ACRI has recently received Cotton Australia BMP accreditation. Over the three years of the project an average of 50Ha of experimental cotton was grown at ACRI on behalf of NSW Department of Primary Industries researchers. Cotton was successfully grown at ACRI over the three year period under a broad array of experimental criteria. The successful growing of cotton in this context is intended to meet the needs for cotton experimentation in agronomy, entomology, farming systems and pathology.

Five sites representing the main cotton growing soil types in the Lower Macquarie Valley were selected and soil sampled in late October and May 2004. Field selection was based on being a representative irrigated cotton soil of the Macquarie Valley as well as irrigation water source. One of the sites sources irrigation water from a moderately brackish (1.0 dS/m) bore. Three sites are supplied by schemes and the other by a river pump.

The pattern of measured is consistent with previous reports, the lighter red soils have significant higher deep drainage rates than the heavier grey soils. The increased drainage under the site irrigated with the saline bore (Bw) may be due to an electrolytical effect in which high EC water partially flocculates the soil and increases deep drainage (Beecher 1992).

The upper 50 cm of the meander plain soil (Bw ) became sodic (ESP greater than 5%) after irrigation compared to the pre irrigated samples. There was no significant change in the Na content the back plain soils due to the 2003-04 irrigation season (Ya, Dr). This result suggests that irrigation during the 2003-04 season on the lighter meander plain soils increased the risk of sodicification of these soils while there was no such effect on the heavier back plain soils.

The change in soil salt stored was calculated and the results show that all sites increased the salt store over the observation period (Fig. 6). The biggest increase occurred on the meander plain soils irrigated with the bore. At this site an additional 3.5 t/ha of salt was stored in the top 2.1 m. This estimate does not account for any effect of leaching by winter rainfall. Previous studies (Friend 2000) showed that winter rainfall has a significant effect on the amount of deep drainage and hence leaching of salts. Again it would be difficult to draw too many conclusions without undertaking additional post winter sampling.

Long term farm soil and water data has been collected and collated for one site. Some historical yield data has also been collected. The yield data was used to pinpoint areas of high and low yield. Initial analysis of the soil data in conjunction with yield maps suggests that areas of low yield also have high sub soil nitrates present after harvest. This suggests that the plant did not or could not access the nutrients. The finding has enabled the grower to eliminate nutrition as a factor in yield. The grower has identified these areas of low yield and high sub soil nitrates as areas of restricted infiltration.

The objective of development of a detailed research proposal that meets alternative funding bodies priorities was not achieved. The original plan was to approach the CW CMA and CRC IF for additional funding. The CW CMA is still being established and the investment plan has yet to be finalised, while the CRC IF will only fund post graduate studies. It is hoped that the CMA will be operational in the later part of 2004 or early part of 2005 and this will allow negotiation of a research agreement

Correct identification of the species of aphid present is a critical step in determining a management strategy. Many winged forms of nonpest aphid species will settle on cotton and test feed, then move on when they find it unsuitable.

Fleabane has become one of the most difficult-to-control weeds in dryland cropping systems in recent years, The weed problem is thought to have resulted from recent changes in farming practices toward greater use of zero tillage, and possibly from recent seasonal conditions that have favoured fleabane growth. Some preliminary studies on fleabane biology indicated that the seed emerged only on or near the soil surface, and that seed persistence was relatively short. The weed seemed to emerge throughout the year, but peak emergence was during spring, particularly under wet conditions. One mature plant can produce an average of 11 0,000 seeds.