Page 1 Page 2 Page 3 Page 4 Page 5 Page 6 Page 7 Page 8 Page 9 Page 10 Page 11 Page 12 Page 13 Page 14 Page 15 Page 16 Page 17 Page 18 Page 19 Page 20 Page 21 Page 22 Page 23 Page 24 Page 25 Page 26 Page 27 Page 28 Page 29 Page 30 Page 31 Page 32 Page 33 Page 34 Page 35 Page 36 Page 37 Page 38 Page 39 Page 40 Page 41 Page 42 Page 43 Page 4430 IREC Farmers' Newsletter No. 197 — Autumn 2017 “It is essential that farmers do everything in their power to preserve the effectiveness of the herbicide groups currently available,” he said. “The key is to take a diverse approach to weed management and, most importantly, remove weeds that survive herbicide applications. This is the best way to keep weed numbers low and when numbers are low, resistant weeds can be controlled more effectively. It’s a numbers game!” Mark suggests that growers check the results of every spray application, looking for individual plants ‘surviving’ or ‘re-growing’ after a spray application that has killed adjacent weeds. This may be a sign that the surviving plants carry the genetic mutation that ‘protects’ them from the herbicide’s mode of action. “If this is observed, the first step is to remove those individual plants before they shed seed,” he said. “It is recommended to have the plants, or their seed, tested to confirm resistance and determine what herbicides those individuals are still susceptible to.” A second warning sign is when a higher rate of herbicide is needed to have the same effect as achieved on the target weed in previous years. Mark called this ‘rate (or dose) creep’ and said that it is the most common sign of resistance to herbicides like paraquat. “Paraquat resistance primarily occurs as a result of a plant having the ability to re-direct the herbicide molecules away from the chloroplasts in the cell and into the cell vacuole, where the herbicide has no effect,” he said. “If you are finding that you now need to use a higher rate of a herbicide such as paraquat, it is time to change how you manage those weeds.” Currently there are 10 weed species with confirmed resistance to paraquat (Group L) and 13 species resistant to glyphosate (Group M) in Australia. The WeedSmart website provides many practical tools for farmers wanting to make their weed control program more diverse and robust to delay herbicide resistance on their farms. Useful websites WeedSmart Australian Herbicide Resistance Initiative Australian Glyphosate Sustainability Working Group Further information Eric Koetz Research Agronomist (Weeds) NSW Department of Primary Industries Wagga Wagga Agricultural Institute T: 02 6938 1954 M: 0413 256 132 E: Mark Congreve Senior Consultant Independent Consultants Australia Network (ICAN) M: 0427 209 234 E: W: WeedSmart WeedSmart is an industry-led initiative aimed at enhancing on-farm practices and promoting the long term sustainability of herbicide use in Australian agriculture. Australian research partners, commercial entities, Government, advisers and growers have joined forces to ensure weed management remains at the forefront of global farming practice. Viable herbicide use will help secure the weed control productivity gains made by the current generation of Australian farmers. Providing our community with surveying and land development solutions Call us on 02 6964 3192 For all your surveying and irrigation design needs including GPS 3D guidance files for landforming of civil and agricultural projects