Botrytis leaf blight (BLB) is a fungal disease that occurs in many of the onion growing areas of the world. The causal organism, Botrytis squamosa, causes leaf spots (lesions) and maceration of leaf tissue resulting in leaf dieback and blighting....

, including insecticides that may be approved for organic production: veg-guidelines.cce.cornell.edu. 5 Boivin, G. and D. L. Benoit. 1987. Predicting onion maggot (Diptera: Anthomyiidae) flights in southwestern Québec using degree-days and common weeds...
entry points for bacterial pathogens that can cause bulbs to rot. Feeding by third-generation larvae on mature onion bulbs can result in an unmarketable product (Fig. 4). Even after onions are undercut, windrowed, and left to dry in the field, bulbs may...

-green, yellowish to brownish areas of irregular size and shape (oval tocylindrical) on infected leaves or seed stalks (Fig. 1). These areas may consist of alternating yellow and green layers of tissue. The causal organism of DM produces fruiting bodies and spores...
the night and morning hours. Secondary Spread The mycelium of DM in leaves of infected onion plants in commercial bulb production fields produces a new crop of spores called conidia in cycles of approximately 11-15 days. As the upper portions of a leaf...