Management of Botrytis Leaf Blight of Onion: The Québec Experience of 20 Years of Continual Improvement.

Botrytis leaf blight (BLB) of onion (Allium cepa) is caused by Botrytis squamosa. The disease has been reported on onion crops in several of the onion production areas of the world including North and South America, Europe, Asia, and Australia, although it is not a problem in arid production regions such as the western United States. In eastern Canada, the disease is generally present every year and is especially severe on cultivars of yellow globe onion. The pathogen biology and disease epidemiology have been intensively researched. Over the last few decades, in the organic soil area of Quebec, extensive research effort has been devoted to the development and evaluation of predictive models and disease management strategies. There has been an active integrated pest management program for onions since the early 1980s, and scouting for disease has played a major role in disease management. In this article, the story of BLB management in eastern Canada over a period of two decades is summarized.