Southern corn leaf blight and stalk rot (Bipolaris maydis, also known as Cochliobolus heterostrophus). Image Credit: Department of Plant Pathology , North Carolina State University, via Bugwood.org used under a Creative Commons Attribution-Noncommercial 3.0 License.

Cochliobolus heterostrophus strain PR9B is a MAT1-1 field isolate, collected by L. Hsu in Poza Rica, Mexico, around the time of the Southern Corn Leaf Blight (SCLB) epidemic. Like the reference strain C5, it is a race O, non T-toxin producing strain. Before 1970, C. heterostrophus was known as an endemic pathogen of minor economic importance, first described in 1925 by Dreschler; after the appearance of race T, this race was named “race O”. Note both fungal races are pathogenic to corn, but race T is highly and specifically virulent on Texas male sterile cytoplasm (Tcms) corn.

References:

• Drechsler, C. 1925. Leaf spot of maize caused by Ophiobolus heterostrophus, the ascigerous stage of a Helminthosporium exhibiting bipolar germination. J. Agric. Res. 31: 701-726.