Onion Disease Guide

A practical guide for seedsmen, growers and agricultural advisors. — Seminis Vegetable Seeds, 2012. — 72 pp.This guide provides descriptions and photographs of the more commonly found diseases and disorders of onion and leek worldwide. For each disease and disorder, the reader will find the common name, causal agent, distribution, symptoms, conditions for disease development and control measures. The photographs illustrate characteristic symptoms of the diseases and disorders included in this guide. It is important to note however, that many factors can influence the appearance and severity of symptoms.
The primary audience for this guide includes onion and leek producers, agricultural advisors, farm managers, agronomists, food processors, chemical companies and seed companies. This guide should be used in the field as a quick reference for information about common diseases and disorders and their control. However, diagnosis of these diseases and disorders using only this guide is not recommended. Even the most experienced plant pathologist relies upon laboratory and greenhouse techniques to confirm suspicions from the field. Moreover, this guide is by no means inclusive of every onion or leek disease. Rather, we present those diseases that are prevalent worldwide. With one exception, insect pests were not included in this publication. Thrips injury was included to compare the unique foliar damage caused by thrips feeding to that caused by infectious diseases and other non-infectious disorders.
A glossary of words used in the text can be found at the end of this guide, along with a list of references for further disease information.C o n t e n t s.
Bacterial Diseases.
Bacterial Blight of Leek.
Bacterial Leaf Streak and Bulb Rot.
Bacterial Soft Rot.
Center Rot.
Enterobacter Bulb Decay.
Slippery Skin.
Sour Skin.
Xanthomonas Leaf Blight.
Fungal Diseases.
Basal Rot.
Black Mold.
Black Stalk Rot.
Blue Mold Rot.
Botrytis Brown Stain.
Botrytis Leaf Blight.
Damping-Off.
Downy Mildew.
Leaf Blotch.
Neck Rot.
Phytophthora Neck and Bulb Rot.
Pink Root.
Powdery Mildew.
Purple Blotch.
Rust.
Smudge.
Smut.
Southern Blight.
Stemphylium Leaf Blight.
Twister.
White Rot.
White Tip.
Yeast Soft Rot.
Nematode Diseases.
Lesion Nematode.
Root-Knot Nematode.
Stem and Bulb Nematode.
Stubby-Root Nematode.
Parasitic Plant.
Dodder.
Phytoplasma Disease.
Aster Yellows.
Virus Diseases.
Iris Yellow Spot.
Leek Yellow Stripe.
Onion Yellow Dwarf.
Non-Infectious Disorders.
Bulb Splitting.
Freeze Damage.
Greening.
Herbicide Injury.
Leaf Variegation.
Nutrient Disorders.
Storm Damage.
Sunscald.
Thrips Damage.
Translucent Scale.
Miscellaneous.
Special Thanks.
Glossary.
References.
Note Pages.