ONION Health Management & Production WEEDS DISEASES INSECTS Preface The purpose of this Onion Health Management and Production publication is to provide an updated, comprehensive, and authoritative account of onion plant health and production practices commonly employed throughout irrigated regions of North America. It is national in scope and practical in emphasis. It is designed to assist in the diagnosis of onion diseases and pests whether in the field, laboratory, or diagnostic clinic, and to provide an overview of pest management strategies that can be employed to reduce their impacts. In addition, an overview of primary production practices is provided. To simplify technical terminology, trade names of products and equipment occasionally will be used. No endorsement of products named is intended nor is criticism implied of products not mentioned. This handbook resulted from the efforts of many people as authors, photographers, reviewers, and sponsors to whom we express our deepest thanks. The editor gratefully acknowledges the support, time and facilities provided by our sponsors and the home institutions of our authors to this effort on behalf of the national onion community. We also wish to thank the many individuals who supplied figures and photographs for this handbook. Howard F. Schwartz Sponsored in part by: USDA NIFA SCRI 2010-01193 Onion Health Management & Production. 2013. Edited by H. F. Schwartz. Colorado State University, Fort Collins, CO 104 pages. “Colorado State University does not discriminate on the basis of race, age, color, religion, national origin or ancestry, sex, gender, disability, veteran status, genetic information, sexual orientation, or gender identity or expression.” ONION HEALTH MANAGEMENT & PRODUCTION Contributing Authors: Diane G. Alston, Entomologist, Utah State Univ., Dept. of Biology, Logan, UT Michael E. Bartolo, Vegetable Crop Specialist, Colorado State Univ., Arkansas Valley Research Center, Rocky Ford, CO Chris Cramer, Plant Breeder, New Mexico State Univ., Dept. of Plant and Environ. Sci., Las Cruces, NM Whitney S. Cranshaw, Entomologist, Colorado State Univ., Bioagr. Sci. & Pest Management, Fort Collins, CO Dan Drost, Horticulturist, Utah State Univ., Dept. of Biology, Logan, UT Lindsey J. du Toit, Seed Pathologist, Washington State Univ., Mt. Vernon NWREC, WA Bhabesh Dutta, Bacteriologist, Univ. of Georgia, Plant Pathology Dept., Tifton, GA Ronald D. Gitaitis, Bacteriologist, Univ. of Georgia, Plant Pathology Dept., Tifton, GA Janet Hardin, Entomologist, Colorado State Univ., Bioagr. Sci. & Pest Management, Fort Collins, CO Brian A. Nault, Entomologist, Cornell University, Dept. of Entomology, Geneva, NY Scott Nissen, Weed Scientist, Colorado State Univ., Bioagr. Sci. & Pest Management, Fort Collins, CO Hanu R. Pappu, Plant Virologist, Washington State Univ., Plant Pathology Dept., Pullman, WA Kimberly Reddin, Director of Public & Industry Relations, National Onion Association, Greeley, CO Howard F. Schwartz, Plant Pathologist, Colorado State Univ., Bioagr. Sci. & Pest Management, Fort Collins, CO Brenda K. Schroeder, Bacteriologist, Washington State Univ., Plant Pathology Dept., Pullman, WA Rajagopalbab Srinivasan, Entomologist, Univ. of Georgia, Entomology Dept., Tifton, GA Stephanie Szostek, Plant Pathologist, Colorado State Univ., Bioagr. Sci. & Pest Management, Fort Collins, CO Mark E. Uchanski, Vegetable Physiologist, New Mexico State University, Dept. of Plant and Environ. Sci., Las Cruces, NM Tim Waters, Area Extension Educator, Washington State Univ., Pasco, WA 3 ONION HEALTH MANAGEMENT & PRODUCTION Table of Contents Introduction and Background ................................................................................................................ 6 By H. F. Schwartz and M. E. Bartolo Nutritional and Culinary Review .......................................................................................................... 8 By K. Reddin and S. Szostek Varietal Reviews By C. Cramer and M. E. Bartolo Market Types .......................................................................................................................... 12 Growing Degree Day Criteria ................................................................................................. 12 Choosing a Variety .................................................................................................................. 12 Establishment Phase ............................................................................................................... 12 Vegetative Phase ..................................................................................................................... 13 Bulbing Phase ......................................................................................................................... 13 Planting & Post-Planting By M. E. Bartolo, C. Cramer, and D. Drost Planting Procedures ................................................................................................................ 15 Seed-bed Preparation .............................................................................................................. 16 Seeding Rates and Spacing ..................................................................................................... 16 Transplanting .......................................................................................................................... 16 Post-Planting Procedures ........................................................................................................ 17 Other Cultural Practices By M. E. Bartolo, C. Cramer, and D. Drost Crop Rotation .......................................................................................................................... 18 Sanitation................................................................................................................................. 18 Fertility Requirements By D. Drost and M. E. Bartolo Nitrogen ................................................................................................................................... 19 Phosphorus .............................................................................................................................. 19 Potassium ................................................................................................................................ 20 Micronutrients ......................................................................................................................... 20 Irrigation Practices ............................................................................................................................... 21 By M. E. Bartolo and D. Drost Harvest and Post-Harvest Procedures By M. E. Bartolo, C. Cramer, and D. Drost Field Operations ...................................................................................................................... 22 Handling .................................................................................................................................. 22 Post-Harvest Procedures ......................................................................................................... 22 Curing ...................................................................................................................................... 23 Storage Conditions .................................................................................................................. 23 USDA Size Classifications ..................................................................................................... 23 Industry Size Classifications ................................................................................................... 23 Onion Cull Disposal................................................................................................................ 23 4 ONION HEALTH MANAGEMENT & PRODUCTION Alternative Onion Production Systems By H. F. Schwartz and M. E. Uchanski Organic Production ................................................................................................................. 25 Homeowner Production .......................................................................................................... 26 Cover Crops ............................................................................................................................ 27 Causes of Production Problems By H. F. Schwartz Plant Damage Description ...................................................................................................... 28 Pest and Disease Forecast Criteria .......................................................................................... 35 General Management Recommendations ............................................................................... 41 Weeds & Their Management .............................................................................................................. 43 By S. Nissen and T. Waters Nematodes & Their Management ....................................................................................................... 47 By H. F. Schwartz Insects & Their Management .............................................................................................................. 49 By D. G. Alston, B. Nault, W. S. Cranshaw, J. Hardin, R. Srinivasan and T. Waters Viral & Phytoplasma Diseases & Their Management ........................................................................ 56 By H. R. Pappu, R. Srinivasan and H. F. Schwartz Bacterial Diseases