Amelioration of root disease of subterranean clover (Trifolium subterraneum) by mineral nutrients

Subterranean clover (Trifolium subterraneum) is a key pasture legume across southern Australia and elsewhere. Decline in subterranean clover pastures was first recognised in Australia during the 1960s and manifests as an increase in weeds and a decrease in desirable legume species. While both root disease and poor nutrition contribute to subterranean clover pasture decline, the relationships between root disease and nutrition have not been determined. The objective of this study was to define these relationships. Field experiments were undertaken to determine the nutritional and pathogen status of soils and subterranean clover from three Western Australian field sites. Subsequently, controlled environment experiments were undertaken to determine the relative severities of tap and lateral root disease and growth of plants when soil cores taken from these three field sites were amended with a complete nutrient solution or a range of individual macro- or micronutrient treatments. Application of a ‘Hoaglands’ complete nutrient solution decreased the severity of tap root disease by an average of 45% and lateral root disease by 32%. Amendment with K alone reduced the severity of tap root disease an average of 32%; while the application of N alone reduced the severity of tap root disease by 33% and lateral root disease by 27%. Application of Hoaglands, K, N or Zn increased shoot and root dry weight, while Mo only increased shoot dry weight. This is the first report to show that mineral nutrients can substantially ameliorate root disease in subterranean clover. The results demonstrate that while root disease limits plant growth, improvement in the nutritional status of nutrient-impoverished soils can significantly reduce root disease. There is significant potential to incorporate nutrient amendments into an integrated and more sustainable approach to better manage root disease and to increase productivity of pasture legumes where soils are inherently nutrient deficient in one or more nutrients

Variability of phenylalanine ammonia-lyase and peroxidase activities in leaves of subterranean clover is determined by their susceptibility to Kabatiella caulivora

Kabatiella caulivora is the causal organism of northern anthracnose or clover (Trifolium spp.) scorch disease. The activities of phenylalanine ammonia-lyase (PAL) and soluble peroxidase were determined in seedling leaves of two cultivars of subterranean clover (T. subterraneum) inoculated with race 1 or race 2 of K. caulivora. A small increase in activity of PAL was recorded in both cultivars 2–4 h post inoculation with either race. A second, large increase in PAL activity was observed only in the incompatible interaction (cv. Daliak inoculated with race 1), increasing 18-fold between 8 and 48 h post inoculation. Peroxidase activity in cv. Daliak increased rapidly within 2 h post inoculation with either race but was significantly higher in the incompatible interaction. Peroxidase activity in cv. Woogenellup increased by 4 h post inoculation with either race, but was significantly lower than that in cv. Daliak. Subsequent increases in peroxidase activity were recorded in both cultivars, however the levels remained constant in cv. Daliak infected with race 1, while activities in the other race-cultivar combinations decreased to control levels. It is hypothesised that the peak of activity of PAL at 48 h, and the rapid increase in peroxidase at 2 h are related to the race-specific resistance response of cv. Daliak to race 1 of K. caulivora, and that minor peaks of activity in the compatible interactions are general defence responses

Evidence for suppression of immunity as a driver for genomic introgressions and host range expansion in races of Albugo candida, a generalist parasite

How generalist parasites with wide host ranges can evolve is a central question in parasite evolution. Albugo candida is an obligate biotrophic parasite that consists of many physiological races that each specialize on distinct Brassicaceae host species. By analyzing genome sequence assemblies of five isolates, we show they represent three races that are genetically diverged by ∼1%. Despite this divergence, their genomes are mosaic-like, with ∼25% being introgressed from other races. Sequential infection experiments show that infection by adapted races enables subsequent infection of hosts by normally non-infecting races. This facilitates introgression and the exchange of effector repertoires, and may enable the evolution of novel races that can undergo clonal population expansion on new hosts. We discuss recent studies on hybridization in other eukaryotes such as yeast, Heliconius butterflies, Darwin’s finches, sunflowers and cichlid fishes, and the implications of introgression for pathogen evolution in an agro-ecological environment

Crop Updates 1999 - Oilseeds

This article contains eighteen papers INTRODUCTION, Paul Carmody, Agriculture Western Australia PLENARY SESSION Transgenic canola in Western Australia: Outlook and challenges, Phil Salisbury, University of Melbourne Farming system issues for herbicide tolerant canola, Rick Madin, Rick Madin and Associates, David Bowran, Agriculture Western Australia Beating blackleg in 1999, Martin Barbetti, Ravjit Khangura, Paul Carmody, Graham Walton, Agriculture Western Australia The Mustard Industry in Australia – Opportunities for a new oilseed, Phil Parker, NSW Agriculture Management of blackleg with fungicides, Ravjit Khangura and Martin Barbetti, Agriculture Western Australia Effect of aphid feeding damage on canola yields in 1998, Francoise Berlandier and Linnet Cartwright, Agriculture Western Australia Post-anthesis duration and rainfall affect oil content of canola, Ping Si, University of West Australia, Graham Walton, Agriculture Western Australia, Nick Galwey and David Turner, University of West Australia Canola responded to high rates of fertiliser in 1998, Wayne Pluske, CSBP Impact of agronomic practices on canola quality, Graham Walton, Agriculture Western Australia Survey reveals widespread infection with two virus diseases in Western Australian canola crops, Roger Jones and Brenda Coutts, Agriculture Western Australia Calculating canola yields and oil contents as a function of soil and fertiliser nitrogen supply, Bill Bowden and Isabel Arevalo-Vigne, Agriculture Western Australia Canola benchmarks 1997/98 – Central Eastern District, Jeff Russell, Agriculture Western Australia Seeding rate affects the yield and some architectural features of canola, Syed H. Zaheer, Nick W. Galwey and David Turner, University of Western Australia Foliar applied fungicides for blackleg, Andrew Simon and Art Diggle, Agriculture Western Australia Farm based demonstration 1998 canola N – Wheel evaluation, Jeff Russell, Agriculture Western Australia Effect of sowing date on seed yield of canola, Dave Eksteen, Agriculture Western Australia Investigating water use of summer crops on the South Coast of Western Australia, Arjen Ryder, Agriculture Western Australia, Bill Crabtree, Western Australia No Till Farming Association, Serena Wyatt, Catchment Landcare Coordinator, Wellstead, Jim Baily, Subasio Downs, Wellstead INTRODUCTION, Paul Carmody, Agriculture Western Australia PLENARY SESSION Transgenic canola in Western Australia: Outlook and challenges, Phil Salisbury, University of Melbourne Farming system issues for herbicide tolerant canola, Rick Madin, Rick Madin and Associates, David Bowran, Agriculture Western Australia Beating blackleg in 1999, Martin Barbetti, Ravjit Khangura, Paul Carmody, Graham Walton, Agriculture Western Australia The Mustard Industry in Australia – Opportunities for a new oilseed, Phil Parker, NSW Agriculture Management of blackleg with fungicides, Ravjit Khangura and Martin Barbetti, Agriculture Western Australia Effect of aphid feeding damage on canola yields in 1998, Francoise Berlandier and Linnet Cartwright, Agriculture Western Australia Post-anthesis duration and rainfall affect oil content of canola, Ping Si, University of West Australia, Graham Walton, Agriculture Western Australia, Nick Galwey and David Turner, University of West Australia Canola responded to high rates of fertiliser in 1998, Wayne Pluske, CSBP Impact of agronomic practices on canola quality, Graham Walton, Agriculture Western Australia Survey reveals widespread infection with two virus diseases in Western Australian canola crops, Roger Jones and Brenda Coutts, Agriculture Western Australia Calculating canola yields and oil contents as a function of soil and fertiliser nitrogen supply, Bill Bowden and Isabel Arevalo-Vigne, Agriculture Western Australia Canola benchmarks 1997/98 – Central Eastern District, Jeff Russell, Agriculture Western Australi

Crop Updates - 2003 Oilseeds

This session covers fifteen papers from different authors ACKNOWLEDGMENTS VARIETIES Large scale canola varietal evaluation in WA, Peter Nelson, Oilseeds WA Performance of IT and TT canola varieties in the medium and high rainfall agzones of WA 2001-02, Graham Walton, Hasan Zaheer and Paul Carmody, Department of Agriculture QUALITY Reproductive biology, cotyledon development and oil accumulation in canola, J.A. Fortescue and D.W. Turner, School of Plant Biology, Faculty of Natural and Agricultural Sciences, The University of Western Australia Plant and environmental factors affecting oil concentration in canola – a mini-review, D.W. Turner, School of Plant Biology, Faculty of Natural and Agricultural Sciences, The University of Western Australia Potential benefits from interspecific crosses between canola and ‘near canola’ quality Indian mustard, Janet Wroth, School of Plant Biology, The University of Western Australia (UWA), Wallace Cowling, School of Plant Biology, UWA and CBWA Pty Ltd, Anh-Van Pham, School of Mathematics and Statistics, UWA NUTRITION, AGRONOMY AND MACHINERY Timing of nitrogen application for producing canola grain and oil, R. F. Brennan, Department of Agriculture Managing canola for soil type and moisture stress, Paul Carmody and Hasan Zaheer Department of Agriculture Machinery lessons from 2002 – canola establishment, Glen Riethmuller, Greg Hamilton and Jo Hawksley, Department of Agriculture Machinery lessons from 2002 – harvesting short crops, Glen Riethmuller, Department of Agriculture Does increasing canola seeding rate reduce the competitiveness of grass weeds? Zaicou-Kunesch, C.M., Zaheer, S.H. and Eksteen, D, Department of Agriculture PESTS AND DISEASES Aphid damage to canola – not all cultivars are equal, Françoise A. Berlandier and Christiaan Valentine, Department of Agriculture Should we be worried about developing insecticide resistance in aphids? Owain Edwards, CSIRO Entomology Benefits provided by treating canola seed with imidacloprid seed dressing, Roger Jones, Brenda Coutts, Lisa Smith and Jenny Hawkes, Department of Agriculture, and Centre for Legumes in Mediterranean Agriculture Blackleg levels in canola in 2002, Ravjit Khangura1, Moin Salam1, Art J Diggle1 and Martin J Barbetti1,2 1Department of Agriculture, 2University of Western Australia DBM in canola, Kevin Walden, Department of Agricultur

Crop Updates 2001 - Oilseeds

ABSTRACT This session covers twenty five papers from different authors: FORWARD, Mervyn McDougall, CHAIRMAN, PULSES AND OILSEEDS PARTNERSHIP GROUP PLENARY 1. Implications of the ‘green-bridge’ for viral and fungal disease carry-over between seasons, Debbie Thackray, Agriculture Western Australia and Centre for Legumes in Mediterranean Agriculture 2. Insect pest development in WA via the ‘green-bridge’, Kevin Walden, Agriculture Western Australia VARIETIES 3. Performance of new canola varieties in AGWEST variety trials, G. Walton, Crop Improvement Institute, Agriculture Western Australia 4. New herbicide tolerant varieties in WA, Kevin Morthorpe, Stephen Addenbrooke, Pioneer Hi-Bred Australia P/L 5. IT v’s TT – Head to head, Paul Carmody, Centre for Cropping Systems, Agriculture Western Australia ESTABLISHMENT 6. Effect of stubble, seeding technique and seed size on crop establishment and yield of canola, Rafiul Alam, Glen Riethmuller and Greg Hamilton, Agriculture Western Australia 7. Canola establishment survey 2000, Rafiul Alam, Paul Carmody, Greg Hamilton and Adrian Cox, Agriculture Western Australia 8. Tramline farming for more canola, Paul Blackwell, Agriculture Western Australia NUTRITION 9. Comparing the phosphorus requirement of canola and wheat in WA, M.D.A. Bolland and M.J. Baker, Agriculture Western Australia 10. Will a rainy summer affect nitrogen requirement: Tailoring your fertiliser decisions using the new nitrogen calculator, A.J. Diggle, Agriculture Western Australia 11. Canola – More response to lime, Chris Gazeyand Paul Carmody, Centre for Cropping Systems, Agriculture Western Australia AGRONOMY 12. Hormone manipulation of canola development, Paul Carmody and Graham Walton, Agriculture Western Australia 13. Yield penalties with delayed sewing of canola, Imma Farre, CSIRO Plant Industry, Michael J. Robertson, CSIRO Sustainable Ecosystems, Graham H. Walton, Agriculture Western Australia, Senthold Asseng, CSIRO Plant Industry 14. Dry matter and oil accumulation in developing seeds of canola varieties at different sowing dates, Ping Si1, David Turner1 and David Harris2 , 1Plant Sciences, Faculty of Agriculture, The University of Western Australia, 2Chemistry Centre of Western Australia 13. Simulating oil concentrations in canola – virtually just the beginning, David Turner1 and Imma Farré2, 1Plant Sciences, Faculty of Agriculture, The University of Western Australia, 2CSIRO Plant Industry, Centre for Mediterranean Agricultural Research PESTS AND DISEASES 14. Further evidence that canola crops are resilient to damage by aphids, Françoise Berlandier and Christiaan Valentine, Entomology, Agriculture Western Australia 15. Management of Diamondback moth (DBM) in canola, David Cook, Peter Mangano, David Cousins, Françoise Berlandier, and Darryl Hardie, Crop Improvement Institute,Agriculture Western Australia 16. Effect of time of sowing in conjunction with fungicides on blackleg and yield of canola, Ravjit Khangura and Martin Barbetti, Agriculture Western Australia 17. Further developments in forecasting aphid and virus risk in canola, Debbie Thackray, Jenny Hawkes and Roger Jones, Agriculture Western Australia and Centre for Legumes in Mediterranean Agriculture 18. Efficiency of selected insecticides for the use on Diamondback Moth in canola, Kevin Walden, Agriculture Western Australia 19. Impact® applied ‘in furrow’ controls blackleg in canola, Cameron Weeks and Erin Hasson, Mingenew-Irwin Group Inc. 20. Effect of time of sowing and Impact® on canola yield, Esperance, Dave Eksteen, Agriculture Western Australia 21. Australian Plague Locust Campaign 2000, Kevin Walden, Agriculture Western Australia WEED CONTROL 22. New herbicide options for canola, John Moore and Paul Matson, Agriculture Western Australia HARVESTING 23. Effects of time of swathing and desiccant application on the seed yield and oil content of canola, Carla Thomas and Lionel Martin, Muresk Institute of Agriculture, Curtin University of Technology DECISION SUPPORT AND ADOPTION 24. Using canola monitoring groups to understand factors affecting canola production in Esperance, Dave Eksteen, Agriculture Western Australia 25. Nitrogen and canola, Dave Eksteen, Agriculture Western Australi

Crop Updates 2000 - Oilseeds

This session covers seventeen papers from different authors: Introduction, Paul Carmody, Centre for Cropping Systems CANOLA AGRONOMY 2. Genotype, location and year influence the quality of canola grown across southern Australia, PingSi1, Rodney Mailer2, Nick Galwey1 and David Turner1, 1Plant Sciences, Faculty of Agriculture, The University of Western Australia, 2Agricultural Research Institute, New South Wales Agriculture 3. Development of Pioneer® Canola varieties for Australian market,Kevin Morthorpe, StephenAddenbrooke, Pioneer Hi-Bred Australia Pty Ltd 4. Canola, Erucic Acid, Markets and Agronomic Implications, Peter Nelson, The Grain Pool of Western Australia 5. The control of Capeweed in Clearfield Production System for Canola, Mike Jackson and ScottPaton, Cyanamid Agriculture Pty Ltd 6. Responsiveness of Canola to Soil Potassium Levels: How Low Do We Have To Go? Ross Brennan, Noeleen Edwards, Mike Bolland and Bill Bowden,Agriculture Western Australia 7. Adaption of Indian Mustard (Brassica juncea) in the Mediterranean Environment of South Western Australia, C.P. Gunasekera1, L.D. Martin1, G.H. Walton2 and K.H.M. Siddique2 1Muresk Institute of Agriculture, Curtin University of Technology, Northam, 2Agriculture Western Australia 8. Physiological Aspects of Drought Tolerance in Brassica napus and B.juncea, Sharon R. Niknam and David W. Turner, Plant Sciences, Faculty of Agriculture, The University of Western Australia 9. Cross resistance of chlorsulfuron-resistant wild radish to imidazolinones, Abul Hashem, Harmohinder Dhammu and David Bowran, Agriculture Western Australia 10. Canola Variety and PBR Update 2000, From The Canola Association of Western Australia 11. Development of a canola ideotype for the low rainfall areas of the western Australian wheat belt, Syed H. Zaheer, Nick W. Galwey and David W. Turner, Faculty of Agriculture, The University of Western Australia DISEASE MANAGEMENT 12. Evaluation of fungicides for the management of blackleg in canola, Ravjit Khangura and Martin J. Barbetti, Agriculture Western Australia 13. Impact-IFÒ: Intergral in the control of Blackleg, Peter Carlton, Trials Coordinator, Elders Limited 14. Forecasting aphid and virus risk in canola, Debbie Thackray, Jenny Hawkes and Roger Jones, Agriculture Western Australia and Centre for Legumes in Mediterranean Agriculture 15. Beet western yellow virus in canola: 1999 survey results, wild radish weed reservoir and suppression by insecticide, Roger Jones and Brenda Coutts, Agriculture Western Australia 16. Are canola crops resilient to damage by aphids and diamond back moths? Françoise Berlandier, Agriculture Western Australia ECONOMIC OUTLOOK 17. Outlook for prices and implications for rotations, Ross Kingwell1,2, Michael O’Connell1 and Simone Blennerhasset11Agriculture Western Australia 2University of Western Australi

Evidence for niche differentiation in the environmental responses of co-occurring mucoromycotinian fine root endophytes and glomeromycotinian arbuscular mycorrhizal fungi

Fine root endophytes (FRE) were traditionally considered a morphotype of arbuscular mycorrhizal fungi (AMF), but recent genetic studies demonstrate that FRE belong within the subphylum Mucoromycotina, rather than in the subphylum Glomeromycotina with the AMF. These findings prompt enquiry into the fundamental ecology of FRE and AMF. We sampled FRE and AMF in roots of Trifolium subterraneum from 58 sites across temperate southern Australia. We investigated the environmental drivers of composition, richness, and root colonization of FRE and AMF by using structural equation modelling and canonical correspondence analyses. Root colonization by FRE increased with increasing temperature and rainfall but decreased with increasing phosphorus (P). Root colonization by AMF increased with increasing soil organic carbon but decreased with increasing P. Richness of FRE decreased with increasing temperature and soil pH. Richness of AMF increased with increasing temperature and rainfall but decreased with increasing soil aluminium (Al) and pH. Aluminium, soil pH, and rainfall were, in decreasing order, the strongest drivers of community composition of FRE; they were also important drivers of community composition of AMF, along with temperature, in decreasing order: rainfall, Al, temperature, and soil pH. Thus, FRE and AMF showed the same responses to some (e.g. soil P, soil pH) and different responses to other (e.g. temperature) key environmental factors. Overall, our data are evidence for niche differentiation among these co-occurring mycorrhizal associates