Susceptibility of Two Corn Hybrids to Bipolaris maydis

Bipolaris maydis ( Nisik ), Shoemaker ( Helminthosporium maydis ) was isolated from leaves of corn plants showing leaf spot symptoms during field visits within Riyadh area in 1998 growing season. Pathogenicity test of Helminthosporium maydis was performed on two corn hybrids Santana and Simesara ( Seed source was Nadek Company in Hail area ) . The two corn hybrids were inoculated in a greenhouse at the fourth to sixth leaf stage of growth by spraying a conidial suspension at the concentration 106 spores per milliliter on the leaves. Disease severity was assessed using classes ranging from 0 – 4 . Results indicated that both hybrids were susceptible to the fungus but Santana was more susceptible than Simesara corn hybrid,