First Report of Leaf Spot Disease (“negrilla”) on Agave Salmiana Otto Ex Salm-Dyck (ssp. Salmiana) Plants Caused by Bipolaris Zeae Zivan in Mexico

Agave genera include slow-growing plants with cultural and economic roots dating back to pre-Columbian times in Mexico. Several species have a widespread presence in the country and are cultivated and/or used directly from the field to obtain various derived products. Agave salmiana is widely used in the region of the High Valleys of Apan, Hidalgo, Mexico. However, fungal diseases are causing considerable losses to Agave crops. For this reason, fungi strains from maguey plants from Apan, Hidalgo, with “Negrilla” disease symptoms were isolated and identified morphologically and molecularly. The results provide information on a new disease disseminated in A. salmiana plants, which causes symptoms such as black spots on the leaves due to pathogenic fungi of the genera Bipolaris. The morphological and molecular characterization located the phytopathogenic fungus as new isolates of Bipolaris zeae. Finally, the re-isolation of the causal agent of the disease was achieved in all pathogenicity tests, verifying that the symptoms observed in the maguey plants were caused by B. zeae, thus corroborating Koch’s postulates, and constituting the first report of this fungus as a pathogen of A. salmiana in Mexico.