Evaluation of Novel Fungicide Products for Control of Botrytis Leaf Blight and Stemphylium Leaf Blight in Onion in Oswego, New York, 2025

Abstract

Botrytis leaf blight (BLB) and Stemphylium leaf blight (SLB), caused by Botrytis squamosa and Stemphylium vesicarium, respectively, are common leaf diseases of dry bulb onion ( Allium cepa) in the ‘muck’ soil production regions of New York. These diseases cause leaf spotting and leaf dieback that may reduce bulb size and quality and yield. The objective of this trial was to identify novel fungicides that have activity on these diseases so that they may be incorporated into sustainable fungicide programs to minimize risk of fungicide resistance.