Ground Cover North : Ground Cover 094 September-October 2011 - North
september – OctOber 2011 GrOund cOver Weeds management / Storage 7 By Nicole Baxter n An internationally recognised authority on herbicide resistance has said the threat to world grain production posed by glyphosate- resistant weeds can be managed by maintaining diversity within farming systems. Professor Stephen Powles, who heads the Australian Herbicide Resistance Initiative (AHRI), said the way glyphosate was used on farms in Australia actually had a direct impact on human health globally. Speaking at the 2011 Western Australian No-Tillage Farmers Association Conference, Professor Powles put the case that glyphosate was as important to world food production as penicillin was to human health. “If you’ve got glyphosate working then do everything you can to keep it working because you’ll be doing yourself and world food production a very big favour,” he said. With almost universal adoption of glyphosate-resistant crops (such as Roundup Ready® technology) in the US corn, cotton and soybean belts, Professor Powles said there was an over-reliance on glyphosate, which had created the resistance problems many growers were now experiencing. On a recent trip to North Carolina, Professor Powles said he spoke to a grower who said: ‘Yes, I’ve got diversity ... it is Roundup Ready® corn, followed by Roundup Ready® soybeans, followed by Roundup Ready® cotton.’ Professor Powles noted that this type of rotation is typical for the southern US, while the Mid West was dominated by glyphosate-resistant corn and soybean. Where glyphosate-resistant crops were used every year he said glyphosate would be driven to redundancy and this would have a major impact on world food production. Over the years, Professor Powles has often visited the US to warn growers and the cropping industry about the potential for resistance to glyphosate if ‘wall-to-wall’ Roundup Ready® crops were planted, but he said his message went largely unheeded and resistance was now a major problem. One of the adverse responses is a swing away from no-till back to soil cultivation for weeds control – so much so that the US soil conservation service has introduced subsidies for growers to employ consultants to evaluate how to keep no-till in the farming system. By contrast, Professor Powles pointed to Canada where, since the mid-1990s, Roundup Ready® canola had been used sustainably as part of a diverse crop-production system. He said the main reason glyphosate- resistant weeds were not an issue in Canada was because the only Roundup Ready® crop in the rotation was canola and wheat was the major crop. This is similar to Australia, reinforcing his argument for diversity in crops and herbicides as the way to sustainability. In Australia there are 134 documented cases of weed populations established as glyphosate resistant: 49 in South Australia, 48 in New South Wales, 23 in Western Australia and 14 in Victoria. To minimise glyphosate resistance in Australia, Professor Powles said it was important to learn from what was happening in the US. “We must do everything to keep diversity in our farming systems. With diversity we confuse the weeds by using different control tools.” Examples of diversity include: n using the double-knock method (glyphosate followed by paraquat); n rotating between different pre-emergent herbicide groups (such as trifluralin, Boxer Gold® and, in 2012, Sakura®); n keeping Clearfield® and triazine- tolerant canola in the system; and n harvest weed-seed management, such as narrow windrow burning, chaff carts or, in future, the Harrington Seed Destructor, to lower weed-seed populations. Professor Powles reminded the conference that the challenge of feeding nine billion people while conserving natural resources was huge. “It will include GM crops, and glyphosate is part of that ... so do everything you can to keep this one-in-100-year chemical working on your farm,” he said. □ n A specialist in grains storage systems, Peter Botta of PCB Consulting, is urging growers to regularly check stored grain to avoid damage from insects, mould and humidity. Mr Botta works across the high-rainfall zones (HRZs) of NSW, Victoria, South Australia and Tasmania as part of a GRDC- funded stored grain extension program. He says CSIRO research recommends growers check their grain every four weeks, but he warned that safety is the main consideration when working with silos. “Never enter a storage area where fumigant has been used,” he says. “Inspection of grain at the surface is ideal, but a probe can be used to detect insects below the surface of the grain.” GRDC Research Code UWA00146 More information: Professor Stephen Powles, 0418 927 181, firstname.lastname@example.org; Australian Glyphosate Sustainability Working Group, www.glyphosate resistance.org.au; Australian Herbicide Resistance Initiative, www.ahri.uwa.edu.au; www.grdc.com.au/uWA00146 INspect to protect stored graIN Mr Botta says sampling by sieving for insects when grain is being loaded for delivery allows growers to safely determine whether it is insect-free or requires treatment. “Keeping samples as a record of loads is good practice in case they are needed for future reference.” Mr Botta also reminds growers that stored grain in the HRZ is prone to mould, humidity and certain pests. “Grain storage in the HRZ is similar to other areas, but the lesser grain borer is more likely to a be a major pest. Humidity is also greater in high-rainfall regions, so aeration can be more difficult.” He says aeration is particularly important to maintain grain quality and reduce insect activity. GRDC-supported research shows that wheat with 12 per cent moisture content stored for six months at 30oC to 35oC (unaerated grain temperature) will have reduced germination percentage and seedling vigour. “Aeration controllers pump dry, cool air through the silo, an effect that is quite difficult to achieve by manually turning the fans on and off.” But he emphasises that all storage facilities need to be checked regularly. “Check fans to make sure they are connected and operating correctly – the smell of the air leaving the storage is a reliable indicator of whether the system is working.” He says the smell of the air should change from humid and warm to fresh when the cooling has passed through the grain. “Keeping grain at the right moisture and temperature levels will reduce the likelihood of insect infestations. If possible, safely check the moisture and temperature of the grain at the bottom and top of the stack regularly.” □ GRDC Research Code DAQ00158 More information: Peter Botta, 0417 501 890; GRDC Stored Grain Information Hub, www.storedgrain.com.au; GRDC High-Rainfall Zone Research, www.grdc.com.au/hrz; www.grdc.com.au/dAQ00158 system dIversIty a key to sustaININg glyphosate phOtO:brAdcOllis SERIOUS COVERAGE YOUR SPRAYER SPECIALIST The Commander TerraForce delivers unprecedented capacity and efficiency. Available with 6500, 8500 and 10000 litre Main Tanks for 36, 38, 40 and 42 metre booms, the TerraForce breaks new ground in broadacre spraying. To find out more call 1300 042 734 or visit www.hardi.com.au Professor Stephen Powles The lesser grain borer is a major pest affecting grains storage in high rainfall zones.
Ground Cover 095 November-December 2011 - North
Ground Cover 093 July-August 2011 - North