First report of Cladosporium leaf spot of spinach caused by Cladosporium variabile in North Carolina.
Cladosporium leaf spot of spinach, caused by Cladosporium variabile (a seedborne pathogen), can result in significant economic losses in the United States. In March 2014, symptoms consistent with Cladosporium leaf spot appeared on spinach cv. Tyee in a greenhouse located in Rowan County, North Carolina. Of 1080 spinach plants, 90 to 100% were infected. Symptoms consisted of small (1 to 3 mm in diameter), circular, tan lesions each outlined with a dark margin on the adaxial surface of the leaf. On severely infected foliage, lesions coalesced to produce relatively large necrotic regions. Based on morphological characteristics and analysis of the histone 3 gene sequence, the causal agent was confirmed as C. variabile. This is thought to be the first report of Cladosporium leaf spot on spinach in North Carolina.