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No matter which refuge is grown, it is critical that they are managed to be most attractive to Helicoverpa moths when Bt cotton is also most attractive. The productivity of refuges varies considerably in space and time, both between and within individual crops and also seasons. Not every dedicated refuge will produce large numbers of susceptible moths, but they need to have the capacity to potentially do so. By chance, some refuges may not be colonised by moths. Others may harbour abundant natural enemies of Helicoverpa (e.g. parasites and diseases). CSIRO research at St George has clearly shown that few refuges within a landscape (about 25 per cent) may produce most (over 50 per cent) of the refuge-derived moths. It is the collective performance of refuges within landscapes that is paramount to success. For a refuge to be most effective, it must be planted close to its corresponding Bollgard II crop (within two km) to improve the chance that its moths will mate with potentially resistant moths from the Bollgard II. Helicoverpa are capable of migrating long distances, but during the cropping season a significant part of the population will remain localised on preferred hosts and move only a few kilometres. The RMP requires growers to ensure that their refuge crops receive adequate nutrition, irrigation (for irrigated refuges), and weed and pest management (excluding Helicoverpa sprays) so that they remain attractive while Bollgard II is grown. A healthy and productive refuge is an asset for the future of the cotton industry, helping to ensure Bt technologies in their current and future forms continue to effectively control Helicoverpa. Farm manager at Auscott Warren, Sinclair Steele, says that while it can be a challenge to manage pigeon pea, not having access to Bt technology due to resistance would be far worse. CHEMICAL ACCREDITATION COURSES Dalby 8/2, St George 19/3, Dirranbandi 19/3, Mungindi 19/3, Toowoomba 6/3, Biloela 27/2, Theodore 27/2, Emerald 26/2, Moura 27/2, Goondiwindi 20/3, Moree 21/3, Narrabri 22/3, Wee Waa 22/3, Gunnedah 6/2, Warren 3/4, Narromine 4/4, Trangie 4/4. If dates/location do not suit please advise of your requirements to enable future planning Accreditation is valid for 5 years – New & Update courses available SUpERvISION SkILLS COURSE Formal management training for managers, supervisors, leading hands or foremen Key Topics: Time Management, Delegation, Establishing people as “People Managers”, Developing “results-oriented” employees, How to develop team work, Coaching & Counselling, Disciplining, Praising, Conducting Staff Appraisals, Occupational Health & Safety, Setting Objectives In-house courses can be arranged * Please call for updated information on course schedules * * Courses can be arranged elsewhere if required * Enquiries and Bookings: Geoff Paton 1800 626 681 Countryco Training pty Ltd “Establishing and managing a healthy refuge is an important part of our operations” says Sinclair. “Pigeon pea refuges are inoculated at planting, and we use residual herbicides to help make sure that refuge crops are healthy and weed free. The location of our refuges is also really important. We try to plant refuges upwind of the cotton in the prevailing wind direction to minimise potential Roundup Ready Herbicide drift onto pigeon pea, and also to make sure refuges aren’t impeding Roundup sprays on our cotton fields. Having healthy, attractive refuges means we are doing our bit for resistance management.” Role of non-mandatory refuges Helicoverpa are polyphagous which means that they feed on a wide range of host crops and vegetation, including cotton. Bt cotton dominates the total area of cotton grown in Australia but at a landscape scale it often forms part of a mosaic of other crops and vegetation. Non-cotton crops and natural vegetation are known to be important for Bt resistance management by providing alternative sources of Bt susceptible moths apart from those produced by the mandatory refuges. But we cannot confidently rely on these unstructured refuges to produce moths because their effectiveness and distribution is highly variable. An important characteristic of mandatory refuges is their synchronicity with the corresponding Bollgard II crop. The timing of refuge planting is dependent on the timing of Bollgard II cotton planting so that the refuge is flowering (both pigeon pea and cotton refuges) at the same time as the Bollgard II. Ideally, refuges should be as or more attractive to Helicoverpa than the corresponding Bollgard II crop to attract females to lay eggs in the refuge. So both structured and unstructured refuges play an important role in delaying resistance. A valuable resource With the industry currently looking at third generation Bt technology (Bollgard III), it is a crucial time for resistance management. CSIRO’s resistance monitoring data has detected resistance genes to both proteins in Bollgard II and a concerning increase in resistance to Cry2Ab. In addition, for the past three seasons CSIRO has performed screens against the new protein in Bollgard II (Vip3A) and found that in H. armigera the frequency of genes conferring resistance is around one in 20 moths. Not only is this higher than expected, it is much greater than the starting frequencies for Cry2Ab. Vip3A resistance genes have also been detected in H. punctigera at a frequency that is higher than expected, and higher than the starting frequencies for Cry2Ab. Work is underway to characterise this Vip3A resistance. This information, along with data on the efficacy of Bollgard III against Helicoverpa (also underway), will be used with information on the frequencies of Cry1Ac, Cry2Ab and Vip3A to determine the RMP for Bollgard III. At this stage it is almost certain that we will not be developing a RMP with a clean resistance slate. Mandatory refuges are a critical component of the current RMP, providing a reliable source of susceptible moths to dilute the population of resistant individuals. It costs money to establish and maintain a healthy and viable refuge but it is an investment to protect the future of Bt cotton in Australia, the value of which is the industry’s continued access to the technology. We cannot afford to not take refuges seriously, and all Bollgard II cotton growers have a responsibility to grow and manage their refuges well. 1 CRDC. 2 UNE. 3 CSIRO. 16 — The Australian Cottongrower December 2012–January 2013
Vip3A resistance genes: A threat to Bollgard III ■ By Sharon Downes 1 , Rod Mahon 1 , Tom Walsh 1 , Bill James 1 , and Sally Ceeney 2 THE insecticides engineered into transgenic cotton come from a soil bacterium called Bacillus thuringiensis (Bt) which produces several different types of toxins. The two toxins in the current variety of Bt-cotton are crystalline or Cry toxins (Cry1Ac and Cry2Ab). Genes that enable resistance to Cry toxins were detected by CSIRO in populations of Helicoverpa species even before these insects were exposed to Bt cotton. In Australia there have been no reports of field failures of Bollgard II due to resistance but the proportions of Helicoverpa spp. which can withstand the Cry2Ab toxin has increased since the cotton variety expressing this toxin became available. Although B. thuringiensis produces many distinct types of Cry toxins, Helicoverpa species are only susceptible to those in the Cry1 (e.g., Cry1Ac, Cry1Ab, Cry1F) and Cry2 (e.g., Cry2Ab, Cry2Aa, Cry2Ae) classes. Within each class, it is likely that insects which are resistant to one toxin are also ‘cross’ resistant to others. This means that if resistance emerges to the Cry1Ac or Cry2Ab toxins in Bollgard II, there are limited alternative Cry toxins for plant breeders to exploit. Vegetative insecticidal proteins (Vips) are also produced by B. thuringiensis. They are toxic to Helicoverpa species, and are structurally quite different to Cry toxins. This means that Vip toxins can be effective against insects that are resistant to Cry toxins, and provide a third Bt class that could be used in transgenic crops. Vip3A resistant moths are killed by Cry1Ac and Cry2Ab. The diagram shows the mortality of Vip3A resistant moths (RR) and Vip3A susceptible moths (SS) moths exposed to no toxin (1), Vip3A (2), Cry1Ac (3), and Cry2Ab (4). First Class Cotton Crop Nutrition Maximise nutrient retention in the First class stress management! High quality compound granular basal ground. Suitable for coating or Perfect foliar for establishment, root fertiliser 10N 10.9P 10.8K + Zinc liquid injection. Organically based stimulation and square retention. and Copper. and microbe friendly! The perfect companion to Urea and UAN. 03 5133 9118 www.omnia.com.au info@omnia.net.au Queensland Brendan Lauman 0438 776 480 blauman@omnia.net.au Central NSW & Tasmania Johan Prinsloo 0488 911 981 jprinsloo@omnia.net.au N U T R I O L O G Y * *the science of growing
Page 1 and 2: Print Post Approved Publication No.
Page 3 and 4: In this issue... Refuge crops - inv
Page 5 and 6: We’re with you from the beginnin
Page 7 and 8: The trouble with buying old technol
Page 9 and 10: The BIG HIT in insect control Regis
Page 11 and 12: NOW REGISTERED FOR SILVERLEAF WHITE
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cotton - Greenmount Press

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