Morphology of a New Pathotype of Bipolaris zeicola (Stout) Shoemaker

Conidia of a new pathotype of Bipolaris zeicola (Stout) Shoemaker, which causes Helminthosporium corn leaf spot (HCLS) on inbreds derived from B73, are morphologically atypical on potato dextrose agar (PDA). The average conidial length on PDA (31.9 μm) is half that on naturally infected leaf (65.2 μm). Conidiogenuous cells terminally and subterminally located on short conidiophores produce new conidia which behave as initial conidia, i.e. they immediately elongate or germinate. Sometimes, they appear in chains. Based on conidial morphology on leaf materials and on wheat straw agar (WSA), the investigated fungus was identified as B. zeicola.