First Report of Cercospora Blight of Asparagus officinalis Caused by Cercospora asparagi in New York

In October 2016, disease was observed on stems and branches of asparagus (Asparagus officinalis) in an organic crop at a fresh market farm in Ontario Co., NY. Lesions were small (< 2 to 3 cm in length), generally oval and gray to tan with a reddish-brown margin. The disease was associated with defoliation on approximately 40% of plants. Conidiophores and conidia typical of Cercospora were observed within the lesions. Morphological characteristics of the fungus were consistent with descriptions of C. asparagi (Braun et al. 2014). Conidiomata were brown, consisting of dense conidiophores on a defined stroma (25 to 100 µm long × 2.5 to 4.5 µm wide). Conidia were solitary, hyaline, straight to curved, acicular, with hila at the base (40 to 90 µm long × 2.5 to 4 µm wide). Fifty µl of T-water (0.06% v/v Tween-20 + 0.02% w/v ampicillin) were placed on individual sporulating lesions. The conidial suspension was transferred to water agar (+ 0.02% w/v ampicillin) and incubated at room temperature. Cultures arising ...