Crop Updates 2007 - Weeds

This session covers thirty two papers from different authors: 1. ACKNOWLEDGEMENTS, Alexandra Douglas CONVENOR – WEEDS DEPARTMENT OF AGRICULTURE AND FOOD WILD RADISH MANAGEMENT 2. Decimate a wild radish seed bank in five years, Peter Newman, Sally Peltzer, Abul Hashem and Aik Cheam, Department of Agriculture and Food 3. High level of seed-set control in wild radish is achievable, Aik Cheam and Siew Lee,Department of Agriculture and Food 4. Wild radish: Best management practice, Aik Cheam and Siew Lee, Department of Agriculture and Food 5. Control of phenoxy resistant wild radish through the combined effects of wheat competition and phenoxy herbicides, Natalie Maguire and Michael Walsh, WAHRI, School of Plant Biology, University of Western Australia 6.Efficacy of florasulam on chlorsulfuron resistant and susceptible wild radish populations in Western Australia, Michael Walsh1 and Dan Cornally2, 1WAHRI, School of Plant Biology, University of Western Australia, 2Dow Agrosciences Australia 7. Does liming to increase soil pH limit the growth and development of wild radish (Raphanus raphanistrum)Matt Willis and Michael Walsh, WAHRI, School of Plant Biology, University of Western Australia IWM TECHNIQUES AND SEEDBANKS 8. Weed trimming – a potential technique to reduce weed seed set, Glen Riethmuller, Abul Hashem and Shahab Pathan, Department of Agriculture and Food 9. Burn narrow windrows in the wind, Peter Newman1and Michael Walsh2, 1Department of Agriculture and Food, 2Research Fellow, WA Herbicide Resistance Initiative 10. Winning the Weed War with the Weed Seed Wizard! Michael Renton, Sally Peltzer and Art Diggle, Department of Agriculture and Food HERBICIDE RESISTANCE AND GENE FLOW 11. Frequency of herbicide resistance in wild oat (Avena fatua) across the Western Australian wheatbelt, Mechelle Owen and Stephen Powles, WA Herbicide Resistance Initiative, School of Plant Biology, University of Western Australia 12. Pollen mediated gene flow of herbicide resistance can occur over long distances doe annual ryegrass (Lolium rigidum): Results of two years with different meteorological conditions, Roberto Busi, Robert Barrett-Lennard and Stephen B. Powles, Western Australian Herbicide Resistance Initiative, School of Plant Biology – University of Western Australia 13. Doublegee has developed resistance to metsulfuron-methyl within WA wheatbelt, Dr Abul Hashem1and Dr Shahab Pathan2, 1Senior Research Officer, and 2Research Officer, Department Agriculture and Food 14. Another case of glyphosate resistance in annual ryegrass confirmes within Western Australia, Dr Abul Hashem1and Dr Shahab Pathan2, 1Senior Research Officer, and 2Research Officer, Department Agriculture and Food 15. Glyphosate resistance in the northern NSW – implications for Western Australian farming systems, Andrew Storrie, Tamworth Agricultural Institute, NSW Department of Primary Industries ALTERNATIVES TO TRIFLURALIN, KNOCKDOWNS, TANK MIXES AND NOVEL USES 16. Alternative pre-emergent herbicides to trifluralin for annual ryegrass control, Mr David Minkey and Dr Abul Hashem, Department of Agriculture and Food, 17. Evaluation of a new pre-emergent herbicide alternative dor the control of trifluralin resistant Lolium rigidum Gaudin (annual ryegrass) in wheat and barley, Craig A. Ruchs, Syngenta Crop Protection Australia Pty Ltd and Dr Peter Boutsalis, University of Adelaide 18. Novel knockdown tank mixes: Results from 12 trials over four years, Shahab Pathan1, Abul Hashem2, Catherine Borger3, Nerys Wilkins and Julie Roche, Department of Agriculture and Food, Western Australia, and 3the University of Western Australia 19. Alternative herbicides for weed control in lupins, Peter Newman and Martin Harries, Department of Agriculture and Food 20. Novel use application of clopyealid in lupins, John Peirce, and Brad Rayner, Department of Agriculture and Food 21. A model to predict grass selective herbicide rates, John Moore, Department of Agriculture and Food CROP AND WEED MANAGEMENT 22. Inter-row weed control in wide row lupin using knockdown-based tank mixes, Dr Abul Hashem1, Ray Fulwood2 and Chris Roberts3, 1Senior Research Officer, Department of Agriculture and Food, 2Farmer, Meckering, WA, 3Technical Officer, Department of Agriculture and Food 23. Timing of weed removal in wide-row lupins, Sally Peltzer, Shahab Pathan and Paul Matson, Department of Agriculture and Food 24. The effect of row spacing and crop density on competitiveness of lupins with wild radish, Bob French and Laurie Maiolo, Department of Agriculture and Food 25. Is delayed sowing a good strategy for weed management in lupins? Bob French, Department of Agriculture and Food 26. Delayed sowing as a strategy to manage annual ryegrass, Department of Agriculture and Food HERBICIDE TOLERANCE 27. The effect of herbicides on nodulation in lupins, Lorne Mills1, Harmohinder Dhammu2 and Beng Tan1, 1Curtin University of Technology, and 2Department of Agriculture and Food 28. Response of new wheat varieties to herbicides, Harmohinder Dhammu, Department of Agriculture and Food 29. Herbicide tolerance of new barley varieties, Harmohinder Dhammu, Vince Lambert and Chris Roberts, Department of Agriculture and Food 30. Herbicide tolerance of new oat varieties, Harmohinder Dhammu, Vince Lambert and Chris Roberts, Department of Agriculture and Food OTHER WEEDY MATTERS 31. Research and extension need for wild radish and other cruciferous weeds, Aik Cheam, Department of Agriculture and Food 32. e-weed – an information resource of seasonal weed management issues, Vanessa Stewartand Julie Roche, Department of Agriculture and Foo

Resistance to acetolactate synthase-inhibiting herbicides in Sonchus oleraceus, Sisymbrium orientale and Brassica tournefortii / Peter Boutsalis.

Bibliography: leaves 147-163.ix, 164 leaves : ill. (some col.) ; 30 cm.The aim of this thesis is to confirm the resistance status of three purported resistant weed species by herbicide screening of outdoor pot grown plants. Field experiments are set up to investigate changes in dormancy and seedbank life of the resistant populations over a three year period. After determining the herbicide resistance spectrum of the resistant biotypes, genetic crosses between resistant and susceptible plants are performed to follow the mode of inheritance of acetolactate synthase (ALS) resistance. "In vitro" ALS enzyme assays in the presence of various herbicides are carried out to reveal a modified ALS enzyme as the main mechanism of resistance in all cases. A molecular investigation of the ALS gene is performed to identify mutations responsible for endowing a resistant enzyme.Thesis (Ph.D.)--University of Adelaide, Dept. of Crop Protection, 199

Multiple resistance to acetohydroxyacid synthase-inhibiting and auxinic herbicides in a population of oriental mustard (Sisymbrium orientale)

A population of oriental mustard from Port Broughton in South Australia was reported as not being controlled by 2,4-D. Dose response experiments determined this population was resistant to both 2,4-D and MCPA, requiring greater than 20 times more herbicide for equivalent control compared to a known susceptible population (from Roseworthy, South Australia) and a population resistant only to the acetohydroxyacid synthase (AHAS)-inhibiting herbicides (from Tumby Bay, South Australia). The Port Broughton population was also found to be resistant to three chemical groups that inhibit AHAS; however, the level of resistance was lower than the known acetolactate synthase–resistant population from Tumby Bay. Herbicides from other modes of action were able to control the Port Broughton population. Assays of isolated AHAS from the Port Broughton population showed high levels of resistance to the sulfonylurea and sulfonamide herbicide groups, but not to the imidazolinone herbicides. A single nucleotide change in the AHAS gene that predicted a Pro to Ser substitution at position 197 in the protein was identified in the Port Broughton population. This population of oriental mustard has evolved multiple resistance to AHAS-inhibiting herbicides (AHAS inhibitors) and auxinic herbicides, through a mutation in AHAS and a second nontarget-site mechanism. Whether the same mechanism provides resistance to both AHAS inhibitors and auxinic herbicides remains to be determined. Multiple resistance to auxinic herbicides and AHAS inhibitors in the Port Broughton population will make control of this population more difficult.Nomenclature: 2,4-D; MCPA; oriental mustard, Sisymbrium orientale Torn.Christopher Preston, Fleur C. Dolman, and Peter Boutsali

Incidence of herbicide resistance in rigid ryegrass (lolium rigidum) across southeastern Australia

Herbicide resistance in rigid ryegrass is an escalating problem in grain-cropping fields of southeastern Australia due to increased reliance on herbicides as the main method for weed control.Weed surveys were conducted between 1998 and 2009 to identify the extent of herbicide-resistant rigid ryegrass across this region to dinitroaniline, and acetolactate synthase- and acetyl coenzyme A (CoA) carboxylase-inhibiting herbicides. Rigid ryegrass was collected from cropped fields chosen at random. Outdoor pot studies were conducted during the normal winter growing season for rigid ryegrass with PRE-applied trifluralin and POST-applied diclofop-methyl, chlorsulfuron, tralkoxydim, pinoxaden, and clethodim. Herbicide resistance to trifluralin in rigid ryegrass was identified in one-third of the fields surveyed from South Australia, whereas less than 5% of fields in Victoria exhibited resistance. In contrast, resistance to chlorsulfuron was detected in at least half of the cropped fields across southeastern Australia. Resistance to the cereal-selective aryloxyphenoxypropionate-inhibiting herbicides diclofopmethyl, tralkoxydim, and pinoxaden ranged between 30 and 60% in most regions, whereas in marginal cropping areas less than 12% of fields exhibited resistance. Resistance to clethodim varied between 0 and 61%. Higher levels of resistance to clethodim were identified in the more intensively cropped, higher-rainfall districts where pulse and canola crops are common. These weed surveys demonstrated that a high incidence of resistance to most tested herbicides was present in rigid ryegrass from cropped fields in southeastern Australia, which presents a major challenge for crop producers. Nomenclature: Chlorsulfuron; clethodim; diclofop-methyl; pinoxaden; tralkoxydim; trifluralin; rigid ryegrass, Lolium rigidum Gaudin; canola, Brassica napus L.Peter Boutsalis, Gurjeet S. Gill and Christopher Presto

A decade of glyphosate-resistant Lolium around the world: Mechanisms, genes, fitness, and agronomic management

Copyright © 2009 BioOne All rights reservedGlyphosate resistance was first discovered in populations of rigid ryegrass in Australia in 1996. Since then, glyphosate resistance has been detected in additional populations of rigid ryegrass and Italian ryegrass in several other countries. Glyphosate-resistant rigid ryegrass and Italian ryegrass have been selected in situations where there is an overreliance on glyphosate to the exclusion of other weed control tactics. Two major mechanisms of glyphosate resistance have been discovered in these two species: a change in the pattern of glyphosate translocation such that glyphosate accumulates in the leaf tips of resistant plants instead of in the shoot meristem; and amino acid substitutions at Pro 106 within the target site, 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS). There are also populations with both mechanisms. In the case of glyphosate resistance, the target site mutations tend to provide a lower level of resistance than does the altered translocation mechanism. Each of these resistance mechanisms is inherited as a single gene trait that is largely dominant. As these ryegrass species are obligate outcrossers, this ensures resistance alleles can move in both pollen and seed. Some glyphosate-resistant rigid ryegrass populations appear to have a significant fitness penalty associated with the resistance allele. Field surveys show that strategies vary in their ability to reduce the frequency of glyphosate resistance in populations and weed population size, with integrated strategies—including alternative weed management and controlling seed set of surviving plants—the most effective. Nomenclature: Glyphosate; rigid ryegrass, Lolium rigidum Gaud. LOLRI; Italian ryegrass, Lolium multiflorum Lam. LOLMU.Christopher Preston, Angela M. Wakelin, Fleur C. Dolman, Yazid Bostamam, and Peter Boutsali

Increasing the value and efficiency of herbicide resistance surveys

The scale of herbicide resistance within a cropping region can be estimated and monitored using surveys of weed populations. The current approach to herbicide resistance surveys is time consuming, logistically challenging, and costly. Here we review past and current approaches used in herbicide resistance surveys with the aims of i) defining effective survey methodologies, ii) highlighting opportunities for improving efficiencies through the use of new technologies and iii) identifying the value of repeated region-wide herbicide resistance surveys. One of the most extensively surveyed area of the world's cropping regions is the Australian grain production region, with in excess of 2900 fields randomly surveyed in each of 3 surveys conducted over the past 15 years. Consequently, recommended methodologies are based on what has been learned from the Australian experience. Traditional seedling-based herbicide screening assays remain the most reliable and widely applicable method for characterizing resistance in weed populations. The use of satellite or aerial imagery to plan collections and image analysis to rapidly quantify screening results could complement traditional resistance assays by increasing survey efficiency and sampling accuracy. Global management of herbicide resistant weeds would benefit from repeated and standardized surveys that track herbicide resistance evolution within and across cropping regions. This article is protected by copyright. All rights reserved

Increasing the value and efficiency of herbicide resistance surveys

The scale of herbicide resistance within a cropping region can be estimated and monitored using surveys of weed populations. The current approach to herbicide resistance surveys is time consuming, logistically challenging, and costly. Here we review past and current approaches used in herbicide resistance surveys with the aims of i) defining effective survey methodologies, ii) highlighting opportunities for improving efficiencies through the use of new technologies and iii) identifying the value of repeated region-wide herbicide resistance surveys. One of the most extensively surveyed area of the world's cropping regions is the Australian grain production region, with in excess of 2900 fields randomly surveyed in each of 3 surveys conducted over the past 15 years. Consequently, recommended methodologies are based on what has been learned from the Australian experience. Traditional seedling-based herbicide screening assays remain the most reliable and widely applicable method for characterizing resistance in weed populations. The use of satellite or aerial imagery to plan collections and image analysis to rapidly quantify screening results could complement traditional resistance assays by increasing survey efficiency and sampling accuracy. Global management of herbicide resistant weeds would benefit from repeated and standardized surveys that track herbicide resistance evolution within and across cropping regions. This article is protected by copyright. All rights reserved