First Report of Exserohilum rostratum Associated with Rice Seed in Venezuela

Area of Science:

• Plant Pathology
• Mycology
• Agricultural Science

Background:

• Rice (Oryza sativa L.) is a vital crop in Venezuela, with fungal diseases posing a major threat to its production.
• The Helminthosporium complex of fungi is a significant constraint on rice yields.

Purpose of the Study:

• To identify fungi associated with rice seeds in Venezuela.
• To determine the pathogenicity of isolated fungi on rice plants.

Main Methods:

• A blotter method was employed to isolate fungi from 150 seeds of cv. INIA-017.
• Fungal isolates were cultured on potato dextrose agar (PDA) and sporulation was induced.
• Pathogenicity tests were conducted on 60-day-old rice plants (cv. Blue Bonnet 50) using spore suspensions of Bipolaris oryzae and Exserohilum rostratum.

Main Results:

• Isolates of Bipolaris oryzae and Exserohilum rostratum were identified from discolored rice seeds.
• Inoculation with B. oryzae resulted in rhombic, red-brown to gray lesions with chlorotic/reddish borders.
• Inoculation with E. rostratum caused elliptical, orange-brown to gray lesions along venation with reddish borders.

Conclusions:

• Bipolaris oryzae and Exserohilum rostratum are pathogenic to rice in Venezuela.
• This study represents the first report of Exserohilum rostratum associated with rice in Venezuela.
• Effective disease management strategies are crucial for mitigating the impact of these fungal pathogens on rice production.