LAUSR

Abstract Outbreaks of blossom blight in coriander (Coriandrum sativum) and caraway (Carum carvi) are common in western Canada, particularly when cool, wet conditions prevail during flowering, which can lead to total crop loss. Earlier attempts to identify the causal organisms were inconclusive, which has hampered blossom blight management and been a barrier for effective resistance breeding in these two crops. In order to address this knowledge gap, the pathogenicity of organisms isolated from coriander and caraway blossoms collected during blossom blight surveys in Saskatchewan in 2015 and 2016 was tested under controlled environment conditions. Isolates of Didymella cari, an undescribed fungus tentatively identified as a Heterosphaeria sp., Fusarium avenaceum, F. graminearum, Botrytis cinerea, as well as an isolate of Sclerotinia sclerotiorum obtained from the USA, were all shown to be pathogenic to coriander blossoms. An isolate of Septoria carvi was isolated from diseased caraway foliage and identified based on spore morphology, disease symptoms and sequence data. This is the first report of Septoria carvi in Canada. Isolates of Heterosphaeria sp. were shown to be pathogenic on caraway blossoms, whereas Septoria carvi and Aureobasidium pullulans failed to cause disease on caraway blossoms under the study conditions.