Ground Cover North : Ground Cover 053 December-January 2005 - North
WEED MANAGEMENT 17 DECEMBER 2004 AFS Licence: 247279 www.abb.com.au We've now got a bigger pool table. We've now got a bigger pool table. WHEAT National Pool 80:10:10 Traditional style pool. Payments not a loan - bulk of payment following delivery. Extended Pool 0:90:10 Defers cash flow into next financial year. Single Payment Pool 0:100 Single payment made at pool conclusion with optional access to a loan facility. BARLEY Standard Pool Cash flow provided through loan facility. Extended Pool Offers a credit drawdown facility. Payments following pool sales. Traditional Pool Advance payment - not a loan. Pools for other commodities at selected sites include: lentils, triticale, chick peas, faba beans, peas, oats, lupins, sorghum. Growing wheat and barley is risky enough, so when it comes to selling, talk to ABB Grain. ABB Grain's recently expanded range of pool options, cash prices and contracts makes us the first port of call. Combine these marketing options with our rapid & secure payments and unbeatable customer service and you can see why ABB Grain is rapidly becoming the grain marketer of choice. For more information contact your local representative or call: ABB Grain Marketing Help Line: 1800 018 205 Paraquat resistance hits ryegrass By EMMA LEONARD Even though 22 weed species worldwide are now resistant to the herbicide paraquat, resistance in Australia was until recently known only in barley grass, silver grass and cape weed. However, scientists at the WA Herbicide Resistance Initiative (WAHRI) have reported the first case of field- evolved paraquat resistance in annual ryegrass, Lolium rigidum, plants grown in South Africa. For 40 years paraquat has played an important role as a non-selective herbicide mainly used pre-sowing or to prevent seed set. Paraquat is particularly important to growers using minimum or no-tillage, or who have weed populations resistant to glyphosate, because paraquat is a cost-effective substitute for glyphosate. Dr Qin Yu and colleagues at WAHRI have been testing the paraquat resistant ryegrass to try and establish its mechanism of resistance. The commercial rate of paraquat to kill annual ryegrass is 200 grams per hectare. Dr Qin Yu established that susceptible populations were killed with 100g/ha , while the resistant populations needed more than 800g/ha, making it 14 times more resistant to paraquat than the susceptible plants. However, the paraquat- resistant ryegrass plants were found to be susceptible to a wide range of other herbicides with different modes of action, including the dims and fops (Group A grass herbicides), glyphosate, diuron, atrazine and sulfonlyureas. Herbicide resistance is usually due to what is called "target site mutation" or to herbicide breakdown by the target species. However, neither of these mechanisms appears to be the cause in Dr Yu's ryegrass plants. This suggests that the resistance is caused by other mechanisms. Dr Yu looked at the uptake and movement of paraquat in resistant and susceptible annual ryegrass plants. Translocation studies were conducted on two, three and four-leaf-stage plants. When a droplet of radioactive-labelled paraquat, at commercial concentration was applied to a fully expanded leaf, more than 90 percent was absorbed within five hours. After 24 hours substantial differences in the distribution of paraquat within the plant were recorded. In the susceptible plants, the paraquat had moved throughout the plant. Leaf wilting, a clear sign of paraquat damage, was seen in both the treated and untreated leaves of the susceptible plants, and subsequently all the plants died. In the resistant plants, the paraquat was retained within the leaf where it was applied, and after 48 hours there were no damage symptoms. The resistant plants survived. Dr Yu and her colleagues are now trying to establish what is preventing the paraquat from being translocated around the plant. Two theories they are exploring are that the resistant plants may be able to push the herbicide into the vacuole at the centre of cells, basically locking it up, or they may bind the paraquat in the cell wall. For graingrowers, the implication of finding paraquat resistance in ryegrass emphasises the need to rotate herbicide groups and to use a range of mechanical and biological as well as chemical control methods. Growers need to be vigilant and monitor weed kill. If weeds treated with recommended rates of paraquat wilt, but grow through the damage, there is a small possibility that they are paraquat resistant. GRDC RESEARCH CODE PDF 15, program 3 For more information: Dr Qin Yu, 08 6488 7041, firstname.lastname@example.org. Exploring the mechanisms of resistance: Drs Qin Yu (left) and Shaobai Huang preparing samples of paraquat- resistant ryegrass. 'The implication of finding paraquat resistance in ryegrass emphasises the need to rotate herbicide groups and to use a range of mechanical and biological as well as chemical control methods.'
Ground Cover 054 February-March 2005 - North
Ground Cover 052 October-November 2004 - North