Rust Diseases of Wheat
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CONCEPTS AND METHODS OF DISEASE MANAGEMENT RUST DISEASES OF WHEAT Authors A.P. Roelfs, Research Plant Pathologist, Cereal Rust Laboratory, University of Minnesota R.P. Singh, Geneticist/Pathologist, CIMMYT Wheat Program E.E. Saari, Leader, Crop Protection Subprogram, CIMMYT Wheat Program CIMMYT Reviewers L.H.M. Broers, H.J. Dubin, M. van Ginkel, S. Nagarajan, and 1. Payne Editor/Coordinator G.P. Hettel CONCEPTS AND METHODS OF DISEASE MANAGEMENT CIMMYT is an internationally funded, nonprofit scientific research and training organization. Headquartered in Mexico, the Center is engaged in a worldwide research program for maize, wheat, and triticale, with emphasis on improving the productivity of agricultural resources in developing countries. It is one of 16 nonprofit international agricultural research and training centers supported by the Consultative Group on International Agricultural Research (CGIAR), which is sponsored by the Food and Agriculture Organization (FAO) of the United Nations, the International Bank for Reconstruction and Development (World Bank), and the United Nations Development Programme (UNDP). The CGIAR consists of a combination of 40 donor countries, international and regional organizations, and private foundations. CIMMYT receives core support through the CGIAR from a number of sources, including the international aid agencies of Australia, Austria, Belgium, Brazil, Canada, China, Denmark, Finland, France, Germany, India, Italy, Iran, Japan, Mexico, the Netherlands, Norway, the Philippines, the Republic of Korea, Spain, Switzerland, the United Kingdom, and the USA, and from the European Economic Commission, Ford Foundation, Inter-American Development Bank, OPEC Fund for International Development, UNDP, and World Bank. CIMMYT also receives non-CGIAR extra-core support from the International Development Research Centre (IDRC) of Canada, the Rockefeller Foundation, and many of the core donors listed above. Responsibility for this publication rests solely with CIMMYT. Correct Citation: Roelfs, A.P., R.P. Singh, and E.E. Saari. 1992. Rust Diseases of Wheat: Concepts and methods of disease management. Mexico, D.F.: CIMMYT. 81 pages. Design: Miguel Mellado Enciso ISBN: 968-6127-47-X Printed in Mexico Design assistants: Eliot Sanchez P., Ma. Concepcion Castro A., J. Manuel AGROVOC descriptors: Disease control, plant diseases, rusts, Triticum spp., wheat. Fouilloux, and J. Luis Delgado. Cover photos: Sergio Pasten AGRIS category codes: H20, F01. and Gene Hettel. Dewey decimal classification: 632.425. CONTENTS ABSTRACT vi PREFACE 1 THE WHEAT RUSTS 2 History 2 The Diseases 2 Epidemiology 3 Host-Pathogen Interactions 5 Specific interactions........................................................................................ 5 Nonspecific interactions.................................................................................. 6 LEAF RUST 7 Epidemiology 7 Hosts 8 Alternate hosts................................................................................................ 8 Accessory hosts.............................................................................................. 9 Primary hosts.................................................................................................. 9 Pathogen 11 Life cycle 12 Virulence 13 Aggressiveness 14 STEM RUST 14 Epidemiology 15 Hosts 16 Alternate hosts.............................................................................. 16 Accessory hosts.............................................................................................. 17 Primary hosts............ 17 Pathogen. 20 Life cycle 20 Virulence 21 Aggressiveness 22 STRIPE RUST 23 Epidemiology 23 Hosts 24 Alternate hosts................................................................................................ 25 Accessory hosts.............................................................................................. 25 Primary hosts......... 25 iii Pathogen 25 Life cycle 26 Virulence 27 Aggressiveness 28 DISEASE CONTROL 28 Genetic Resistance.... 28 Chemical (Fungicide) Control 29 Cultural Methods 30 Eradication of the Alternate Host 31 TECHNIQUES FOR STUDY OF RUST DISEASES 31 Inoculum Production 31 Spore increase 31 Seedling plants 31 Adult plants 32 Spore collection 32 Tapping 32 Cyclone collectors 33 Collecting small samples 33 Single spore technique 33 Spore storage................................................................................................. 34 Room temperature..................................................................................... 34 Refrigeration 34 Vacuum drying 34 Liquid nitrogen 34 Ultra-low refrigeration 35 Inoculation Methods 36 Dusting 36 Brushing......................................................................................................... 36 Injection 41 Spraying 41 Spore carriers 41 Talcum powder 41 Mineral oils.................................... 41 Water 42 Disease Scoring 42 Seedling studies............................................................................................. 43 Infection types........................................................................................... 43 Latent period 44 Receptivity 44 Adult plant studies 45 iv Testing for Resistance 47 Seedlings ", " ", ," ",... 47 Specific type resistance 47 Nonspecific type resistance 48 Receptivity , , " " "., , ", , ".. , ,.,............. 48 Adult plants " , " , ", , , 48 Low receptivity ., ' ' , ,., ' ,., ,., , '.',.. 50 Latent period , , , ' ,., ' ,., ,.' ' ,..... 50 Slow-rusting " " ,' ' , ", ", ", ", ,.",."....... 50 Epidemiology Studies 51 Favorability of environment for an epidemic 51 Sources of inoculum , " " ", ", "", "" ,, .. '.... 52 Alternate host " ", ,' ", ,., ", ", '.' ", '. '.' """ 52 Exogenous inoculum " ", , ", , "", ,.'.' ,.",'.......... 52 Endogenous inoculum "" ", " , ", "" ,.. , 53 Monitoring disease development 54 Fungicide Evaluation 54 Seed treatment , , ', " , ,., ", ", ,, ".. " ".",.......... 55 Soil treatment .. , , , , ", ", '.................. 55 Foliar treatment .. " , " , , ", , , , 55 Field experiments , , , " ,., ", " ", ", .. , ",.,.. 55 Yield Loss Studies 56 Physiologic Race Surveys 60 Wheat leaf rust ,"" ", ', ", ", ", ", "... 61 Wheat stem rust .", , ", ", .. "" , , , "" '" "", 62 Wheat stripe rust , , " "" " ", " ", ,.. ",.... 62 Genetic Basis of Resistance 63 Gene postulation .", .. ,., , " ", "", ", "" "." .. ,.......... 63 Genetic analysis , " "", ' , , 64 Cytogenetic analysis , " '".................................................... 66 Strategies for Using Resistance 68 Gene pyramids, , , ", ", , ", " ",... 68 Gene deployment "" ", " " " ", " , , 69 Cultivar mixtures (multivars) and multilines 69 REFERENCES CITED 70 GLOSSARY 80 COLOR PLATES Adult Plant Host Responses........................................................................... 37 Symptoms and Spore Morphology.................................................................. 38 Seedling Infection Types 40 v ABSTRACT Roelfs, A.P., R.P. Singh, and E.E. Saari. 1992. Rust Diseases of Wheat: Concepts and methods of disease management. Mexico, D.F.: CIMMYT. 81 pages. The rust diseases of wheat are among the most studied of the plant diseases. Since Tozzetti and Fontana in 1767, there has been almost an endless list of scientific publications concerning the rust pathogens, the rust diseases, and rust resistance. This publication reviews some of the more recent scientific literature concerning the pathogens Puccinia recondita f.sp. tritici, P. graminis f.sp. tritici, and P. striiformis f.sp. tritici; the diseases leaf rust, stem rust, and stripe rust; and the resistance to the pathogens. The goal is to provide a single source of information for isolated scientists and new students. A brief history and general description of the wheat rusts are followed by adetailed summary of each of the rust diseases, their epidemiology, their hosts (including resistance), and their pathogens (including virulences). Methods for disease control through resistance, chemicals, and cultural methods are discussed. Techniques are presented for inoculum production, collection, and storage; inoculation methods; disease scoring; testing for resistance; epidemiology, yield loss, and physiologic race studies; isolation of resistance genes; and utilization of resistance. Other Manuals in this Series Stubbs, RW., J.M. Prescott, E.E. Saari, and H.J. Dubin. 1986. Cereal Disease Methodology Manual. Mexico, D.F.: CIMMYT. Eyal, Z., A.L. Scharen, J.M. Prescott, and M. van Ginkel. 1987. The Septoria Diseases of Wheat: Concepts and methods of disease management. Mexico, D.F.: CIMMYT. vi PREFACE This publication is a much needed reference concerning the three rust diseases of wheat (leaf, stem, and stripe). It represents one of aseries of wheat disease technical manuals being developed by CIMMYT. In 1976, a "Cereal Disease Methodology Manual" was contemplated and it finally materialized in 1986. Shortly after its publication, a group of individuals conceived the idea of a series of more focused manuals devoted to specific diseases and aimed at a developing country audience. Drs. H.J. Dubin, A.R. Klatt, J.M. Prescott, E.E. Saari, RW. Stubbs, and E. Torres should be especially acknowledged for getting this series of manuals on track. In 1987, the award-winning "Septoria Diseases of Wheat" was published. Now, in 1992, the rust manual becomes the third contribution to the series. A manual devoted to the smuts and bunts of wheat is in the early development stages and scheduled for publishing