Agricultural Weed Assessment Calculator: An Australian Evaluation

Weed risk assessment systems are used to estimate the potential weediness or invasiveness of introduced species in non-agricultural habitats. However, an equivalent system has not been developed for weed species that occur in agronomic cropland. Therefore, the Agricultural Weed Assessment Calculator (AWAC) was developed to quantify the present and potential future adverse impact of a weed species on crop production and profitability (threat analysis), thereby informing or directing research, development, and extension (RDE) investments or activities. AWAC comprises 10 questions related primarily to a weed’s abundance and economic impact. Twenty weed species from across Australia were evaluated by AWAC using existing information and expert opinion, and rated as high, medium, or low for RDE prioritization based on total scores of 70 to 100, 40 to <70, or <40, respectively. Five species were rated as high (e.g., Lolium rigidum Gaud.), eight were rated as medium (e.g., Conyza spp.), and seven were rated as low (e.g., Rapistrum rugosum L.). Scores were consistent with the current state of knowledge of the species’ impact on grain crop production in Australia. AWAC estimated the economic or agronomic threat of 20 major or minor agricultural weeds from across Australia. The next phase of development is the testing of AWAC by weed practitioners (e.g., agronomists, consultants, farmers) to verify its utility and robustness in accurately assessing these and additional weed species

Herbicide-Resistant Weed Seeds Contaminate Grain Sown in the Western Australian Grainbelt

Preventing the introduction of weeds into the farming system through sowing of clean seeds is an essential component of weed management. The weed seed contamination of cleaned grain and herbicide resistance levels of the recovered weed seeds were examined in a study conducted across 74 farms in the Western Australian grainbelt. Most farmers grew and conserved their own crop seed. The majority of cleaned samples had some level of seed contamination from 11 foreign weed and volunteer crop species, with an average of 62 seeds 10 kg−1 grain, substantially higher than the 28 seeds 10 kg−1 grain expected by farmers. The most common weed contaminants across all samples were rigid ryegrass, wild radish, brome, and wild oat.When categorized by crop type, rigid ryegrass was the most frequent contaminant of cereal crops (barley and wheat), however wild radish was the most frequent contaminant of lupin crops. Uncleaned crop seed samples had almost 25 times more contamination than cleaned crop seed. Herbicide resistance was highly prevalent within rigid ryegrass populations recovered from cleaned grain except for glyphosate, which controlled all populations tested. Some resistance was also found in wild radish and wild oat populations; however, brome was susceptible to fluazifop. This study has shown that farmers are unknowingly introducing weed seeds into their farming systems during crop seeding, many of which have herbicide resistance

Crop Updates - 2009 Katanning

This session covers seventeen papers from different authors GM canola – How will it affect the way I farm? Murray Scholz, 2008 Nuffield scholar, Southern NSW Eight years of IWM smashes tyegrass seed banks by 98% over 31 focus paddocks, Peter Newman, Glenn Adam & Trevor Bell, Department of Agriculture and Food The global economic climate and impacts on agriculture, profile on Michael Whitehead Rabobank New York Lessons from five years of cropping systems research, W.K. Anderson, Department of Agriculture and Food Case study of a 17year old agricultural lime trial, C. Gazey, Department of Agriculture and Food, J. Andrew, Precision SoilTech and R. Pearce, ConsultAg Fertilising in a changing price environment, Bill Bowden, Wayne Pluske and Jeremy Lemon, Department of Agriculture and Food Fact or Fiction: Who is telling the truth and how to tell the difference? D.C. Edmeades, agKnowledge Ltd, Hamilton Forecast disease resistance profile for the Western Australian barley crop over the next three years, JJ Russell, Department of Agriculture and Food Malting barley varieties differ in their flowering date and their response to change in sowing date, BH Paynter and JJ Russell, Department of Agriculture and Food Decimating weed seed banks within non-crop phases for the benefit of subsequent crops, Dr Davis Ferris, Department of Agriculture and Food Autumn cleaning yellow serradella pastures with broad spectrum herbicides – a novel weed control strategy that exploits delayed germination, Dr Davis Ferris, Department of Agriculture and Food Emerging weeds in changing farming systems, Dr Abul Hashen, Department of Agriculture and Food More glyphosate-resistant annual ryegrass populations within Western Australia, Dr Abul Hashem and Dr Catherine Borger, Department of Agriculture and Food Reasons to use only the full label herbicide rate, Stephen B. Powels, Qin Yu, Mechelle Owen, Roberto Busi, Sudheesh Manalil, University of Western Australia Flaxleaf fleabane – coming to a property near you! Sally Peltzer, Department of Agriculture and Food Glyphosate – the consequences of cutting rates! Sally Peltzer and David Minkey, Department of Agriculture and Food Benefits of crop rotations/break crops in managing soil moisture, soil health, weeds and disease – an overview, Raj Malik, Department of Agriculture and Foo

Crop Updates 2005 - Geraldton

This session covers seventeen papers from different authors 2005 Seasonal Outlook, David Stephens and Nicola Telcik, Department of Agriculture Horses for Courses – using the best tools to manage climate risk, Cameron Weeks, Mingenew-Irwin Group / Planfarm and Richard Quinlan, Planfarm Agronomy Global influences driving Australian agriculture, Tony Harman, Australian Government Department of Agriculture, Fisheries and Forestry Wheat yield and quality improvements – where have they come from and can we have more? Wal Anderson, Department of Agriculture Rotations for nematode management, Vivien A. Vanstone, Sean J. Kelly, Helen F. Hunter and Mena C. Gilchrist, Department of Agriculture Integrate strategies to manage stripe rust risk, Ciara Beard, Geoff Thomas, Robert Loughman, Kith Jayasena and Manisha Shenkar, Department of Agriculture Frequency of herbicide resistance in wild radish populations across the WA wheatbelt, Dr Michael Walsh, Mechelle Owen and Prof. Stephen Powels, University of Western Australia The incidence and severity of wild radish resistance in the NAR – results from an in-situ survey, Rob Grima and Andrew Blake, Elders Limited Stubble management: the pros and cons of different methods, Bill Bowden, Department of Agriculture, Mike Collins WANTFA Effectiveness of Zinc Application Methods in Wheat, Luigi Moreschi, CSBP Know your Mo, Douglas Hamilton, Department of Agriculture Atrazine contamination of groundwater in the agricultural region of Western Australia, Russell Speed1, Neil Rothnie2, John Simons1, Ted Spadek2, and John Moore1, 1Department of Agriculture, 2Chemistry Centre (W.A.) Comparison of canola varieties in the Northern Agricultural Region in 2004, Graham Walton Department of Agriculture Pasture rotations are a promising option for sandplain production, Nadine Eva, Department of Agriculture Zone management can improve profit on sandplain, Bindi Webb, Damian Shepherd, Department of Agriculture, David Forrester, Davejeff Farms, casuarinas via Geraldton, Peter Tozer, Department of Agriculture Crop leftovers: what’s in stubble for sheep? Roy Butler and Keith Croker, Department of Agriculture Realising Rural Equity, Nathan Windebank, Australian Agricultural Contracts Limite

What is the latest random weed resistance survey telling us about paraquat and 2,4-D?

Take home messages • Resistance to the Group 22 herbicides paraquat and paraquat + diquat has been found in feathertop Rhodes grass (Chloris virgata) and tall fleabane (Conyza sumatrensis), respectively • 2,4-D (Group 4) resistance has been found in 5 and 8% of common sowthistle and wild radish populations respectively from the northern cropping region • Group 22 herbicides are important components of the double knock strategy commonly used for effective control of many northern region weeds. Alternative herbicide options for this use practice are limited • To manage herbicide resistance, alternative herbicide and non-chemical tactics should be used in combination

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