Is Associated with Necrotic Lesions in the Tar Spot Disease Complex? A Culture-Based Survey of Maize in Mexico and the Midwestern United States.

Tar spot, caused by , is an emerging disease of corn in the United States. Stromata of  are sometimes surrounded by necrotic lesions known as fisheyes and were previously reported to be caused by the fungus  . The association of  with fisheye lesions has not been well documented outside of initial descriptions from the early 1980s. The objective of this work was to assess and identify -like fungi associated with necrotic lesions surrounding stromata using a culture-based method. In 2018, corn leaf samples with fisheye lesions associated with tar spot stromata were collected from 31 production fields across Mexico, Illinois, and Wisconsin. Cultures of pure isolates collected from Mexico believed to be were included in the study. A total of 101 /-like isolates were obtained from the necrotic lesions, and 91% were identified as  spp., based on initial ITS sequence data. Multi-gene (ITS, TEF1-α, RPB1, and RPB2) phylogenies were constructed for a subset of 55 isolates; , , and  reference sequences were obtained from GenBank. All the necrotic lesion isolates clustered within  lineages and were phylogenetically distinct from the  clade. All isolates from Mexico belonged to the species complex, whereas >85% of the U.S. isolates grouped within the  species complex. Our study suggests that initial reports of were misidentifications of resident spp. [Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.