Grey leaf spot is a serious yield-reducing disease of maize (Zea
mays) in many parts of the world where this crop is cultivated. The
causal organism associated with the disease is Cercospora
zeae-maydis. Two potential sibling species have been recognized as Groups
I and II. The DNA sequences for the internal transcribed spacers (ITS1 &
ITS2), the 5.8S rRNA gene, elongation factor 1-α, histone H3, actin and
calmodulin gene regions suggest that Groups I and II are two distinct species.
Furthermore, Cercospora zeae-maydis (Group I) can be distinguished
from C. zeina sp. nov. (Group II) by its faster growth rate on
artificial media, the ability to produce cercosporin, longer conidiophores,
and broadly fusiform conidia. A PCR-based test that distinguishes the two
species was developed using species-specific primers designed from the histone
H3 gene