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Common Diseases of Small Grain Cereals A Guide to Identification F.J . Zillinsky CENTRO INTERNACIONAL DE MEJORAMIENTO DE MAE Y TRIG0 INTERNATIONAL MAIZE AND WHEAT IMPROVEMENT CENTER Londres 40, Apdo. Postal 6-641, 06600, MBxico, D.F., MBxico Partial funding for this publication was provided on a special project basis by the United Nations Development Programme (UNDP), Rocke- feller Foundation (RF), and the Australian De- velopment Assistance Bureau (ADAB). Cover: Bacterial stripe, caused by Xanthomonas translucens, on barley (photo: S. Fuentes) Cover design: Anita Albert Acknowledgements As with nearly all major publications, this book State stripe virus; Sefiora Haydee Barreiro de is the result of the interest and efforts of many Villalpando, for her tireless efforts in preparing and people. For their help I am indebted and greatly maintaining the records of disease observations and appreciative; they are mentioned here in no par- photographs. ticular order. This book could not have been developed I would first like to acknowledge the many without the financial support of the United Nations helpful comments and the information provided by Development Programme (UNDP), the Rockefeller the reviewers of this document. Thanks go to: Dr. Foundation ( R F), and the Australian Development R. J. Metzger, Oregon State University (USA), the Assistance Bureau (ADAB). Their continuing major source of information on loose, covered and enthusiasm and support for this project is much flag smuts, common and dwarf bunts, and other appreciated. In this regard, I would also like to diseases of winter cereals; Dr. M. B. Moore, Profes- acknowledge and thank Dr. Clive James, Deputy sor Emeritus, University of Minnesota (USA), for Director General for Research, CIMMYT, for his his constructive review and contribution of photo- efforts in assuring adequate funding, as well as for graphs; Dr. H. J. Dubin, CIMMYT, who provided a his ideas and assistance in the conceptualization of great deal of general information on disease this document. organisms, especially those prevalent in the Andean As a group, CI MMYT's Information Services region of South America; Dr. P. A. Burnett, Unit, under the leadership of Mr. Christopher CIMMYT, for his review of the section on viral and Dowswell, has been extremely helpful in the prepa- mycoplasmal diseases and hisassistance in obtaining ration of this book. Special thanks go to: Mr. Tiffin photographs; Dr. M. V. Wiese, University of Idaho Harris, for his editorial and design support; Sefior (USA) and author of the Compendium of Wheat Fernando Rulfo, for the Spanish translation; Mari- Diseases (APS, 1977), for his careful review of the cela A. de Ramos and Silvia Bistrain R., for their draft manuscript and kind permission to freely patience and help in typesetting various drafts; utilize the Compendium as a source of information; Anita Albert, special consultant to CIMMYT in Dr. E. T. Torres, CIMMYT, for his review and publication design from Iowa State University, for editing of the Spanish translation; Dr. Rkal-L. some last minute design suggestions that improved Pel letier, McGill University (Canada), for his the book's utility and appearance; Miguel Mellado, thorough review and for the translation and for his exceptional job of preparing the guidebook editing of the French version of this document. for the printer. Thanks should also go to Mr. Special thanks go to the following people: Armon Roschen of Viking Press, Inc., for his help Dr. J. M. Walker, CMI (Kew, England), for infor- in carrying this project to completion. mation and references and for his willingness to Finally, a special note of appreciation to my work with me in East Africa and Mexico in wife, Hilda, whose support and faith over the years identifying the diseases afflicting wheat, triticale have enabled me to pursue my career wherever it and barley; Lucie Gilchrist, Pathologist, Temuco, led me. It is to her that I dedicate this book. Chile, for making available to me her research information pertaining to fusarium diseases, yellow leaf blotch (tan spot) of wheat, and Free Dr. Frank Zillinsky Preface Dr. Frank Zillinsky came to CIMMYT in photographs and disease observations for his own December, 1967, from the Ottawa Agricultural edification. About nine months before Frank's Research Station, where he was employed for some scheduled retirement from CIMMYT, Norman 17 years by the Canada Department of Agriculture Borlaug suggested that hundreds of agricultural as a Cereal Crop Specialist. He was appointed as the researchers in developing countries and elsewhere leader of CIMMYT's triticale improvement program, could benefit from the kind of book Frank had and held that position until his retirement from sought but not found. He also suggested that CIMMYT in July, 1982. Under Frank's guidance, Frank was the person best qualified to write such a triticale germplasm underwent very rapid improve- book. Hence, this guidebook was prepared, drawing ment, from not much more than a biological heavily on Frank's own collection of photographs curiosity to the threshold of widespread commercial and knowledge of small grain diseases, but with cultivation. That alone is an accomplishment which significant input from friends and collegues the would satisfy most agricultural researchers, yet world over. Frank offered more. Plant diseases are probably the greatest con- Though not formally trained as a cereal straint to increasing global small grains production pathologist, Frank was often confronted with the in the 1980s and beyond. Accordingly, CIMMYT need to identify diseases afflicting various small is placing a very high priority on breeding wheat, grain cereals. Characteristically, Frank studied in triticale and barley for enhanced resistance to his spare time to develop this necessary expertise. various diseases, and we encourage national pro- To his disappointment, he found no publications grams in developing countries to do the same. In designed specifically to help a person in his situa- fact, the essence of CI MMYT's wheat improvement tion: a plant breeder who needed to identify the strategy lies in multilocation testing and a heavy re- diseases affecting his crops. liance on national program staff for performance For many years, Frank worked closely with evaluations of germplasm. Moreover, many develop- cereal pathologists from all over the world, study- ing countries now have sophisticated plant breeding ing, learning, and accumulating thousands of programs capable of making valuable contributions to improving disease resistance. Success in breeding for enhanced disease resistance will be the result of a cooperative effort among many national programs and CIMMYT, and will require the free exchange of germplasm and performance data. To develop useful breeding objectives and effective crossing plans, accurate information as to which diseases are affecting which cul- tivars is needed, as well as data on the severity of affliction. This guidebook addresses the problem of accurate disease identification. We strongly believe it is a necessary addition to the literature and that it will prove useful to thousands of agricultural researchers all over the world. It is a significant achievement, a fitting capstone to Frank's distin- guished career, and perhaps the most important publication to be recently forthcoming from the Cl MMYT Wheat lmprovement Program. Dr. Frank Zillinsky Byrd C. Curtis Director, CIMMYT Wheat Facing page: Triticale seed (wheat x rye) lmprovement Program Contents Introduction Objectives and scope of this guidebook Field and laboratory techniques and equipment Collecting and preserving samples Preparing samples for the laboratory Disease groups and their general symptoms The rusts Stem rust (Puccinia graminis) Leaf rust of wheat (P. recondita) Leaf rust of barley (P. hordei) Stripe rust (P. striiformis) Crown rust of oats (P. coronata) Hyperparasite of rust (Darluca filum) Helminthosporium diseases Spot blotch (Helminthosporium sativum - Perfect stage: Cochliobolus sativus) Yellow leaf blotch, or tan spot (H. tritici-repentis - Perfect stage: Pyrenophora tritici-repen tis) Leaf blotch of oats (H. avenae - Perfect stage: Pyrenophora avenae) Net blotch (H. teres - Perfect stage: Pyrenophora teres) Barley stripe (H. gramineum - Perfect stage: Pyrenophora graminea) Zonate eyespot (H. giganteum, or Drechslera gigantea) Cereal leaf blotch and foot root (H. spiciferum - Perfect stage: Cochliobolus spicifer) Septoria complex and septoria-like diseases Speckled leaf blotch (Septoria tritici - Perfect stage: Mycosphaerella graminicola) Glume blotch (S. nodorum - Perfect stage: Phaeosphaeria nodorum) Septoria leaf blotch of oats, wheat and triticale (S. avenae - Perfect stage : Phaeosphaeria avenaria) Septoria leaf blotch of barley (S. passerinii) Ascoch yta leaf spot (Ascochy ta graminicola) Phaeoseptoria leaf blotch (Phaeoseptoria vermiformis) Smuts and bunts Loose and covered smuts (Ustilago species) Loose smut of barley and wheat [U. nuda (U. tritici)] Black loose smut of barley and oats [U. nigra (U.a venae)] Covered smut of barley and oats [U. horde; (U. kolleri)] Common and dwarf bunts, or stinking smut (Tilletia species) Karnal bunt (Tilletia indica, formerly Neovossia indica) Flag smut (Urocystisa gropyri) 59 Fusarium diseases 63 Scab and root rot (Fusarium species) 63 Fusarium graminearum - Perfect stage: Gibberella zeae 64 Fusarium culmorum 65 Fusarium avenaceum - Perfect stage: Gibberella avenacea 66 Fusarium equiseti - Perfect stage: Gibberella intricans 67 Fusarium leaf blotch and snow mold (F. nivale - Perfect stage: Calonec tria nivalis) 71 Miscellaneous root and crown diseases 74 Cephalosporium stripe (Cephalosporiumg ramineum) 75 Take-all (Ophiobolus graminis - renamed: Gaeumannomyces graminis) 77 Eyes pot (Pseudocercosporellah erpotrichoides) 78 Sclerotium wilt, or southern blight (Sclerotium rolfsii) 80 Anthracnose (Colletotrichum graminicola) 8 1 Downy mil dew (Scleropht hora macrospora) 83 Miscellaneous leaf and head diseases 85 Powdery mildew (Erysiphe graminis) 87 Scald (Rhynchosporium secalis) 88 Cercospora spot (Cercospora apii) 89 Ergot (Clavicepsp urpurea) Saprophytic and weakly pathogenic fungi Alternaria species Stemphylium botryosum Cladosporium species Pleospora species Torula species Phoma species Epicoccum nigrum Cercosporidium graminis Bacterial diseases Bacterial stripe and black chaff (Xanthomonas transluscens) Basal glume rot (Pseudomonas atrofaciens) Halo blight of oats (P. coronafaciens) Bacterial spike blight (Corynebacterium tritici) Bacterial leaf blight (P. syringae) Viral and mycoplasmal diseases Aphid-transmitted Barley yellow dwarf (BYD) Free state streak Others Leafhopper-transmitted American wheat striate Chloris striate mosaic virus (Australian wheat striate mosaic) Russian wheat mosaic Enanismo de NariRo Aster yellows Planthopper-transmitted Hoja blanca of rice African cereal streak European wheat striate mosaic 117 Others 1 18 Mite-transmitted 1 18 Wheat streak mosaic 1 19 Agropyron mosaic and rye grass mosaic 1 19 Wheat spot mosaic 120 Soil-borne 120 Wheat soil-borne mosaic 120 Wheat spindle streak mosaic 121 Seed-borne 121 Barley stripe mosaic 121 Barley mosaic 123 Injury from nematodes and other pests 123 Nematodes (eel worms) 125 Insects 129 Birds and mammals 131 Physiological and genetic disorders 134 Nutrient deficiencies and environmental stresses 135 Soil pH 136 Soil toxicity 136 Drought 137 Excessive moisture 137 Chemical injury and soil residues 138 Frost and hail damage 139 Glossary and selected references