Cochliobolus heterostrophus (Southern corn leaf blight fungus) | BCH-ORGA-SCBD-110853 | Organism | Biosafety Clearing-House


Organism (ORGA)

last updated: 25 Aug 2016
Organism information
Cochliobolus heterostrophus
Kingdom Fungi
Phylum Ascomycota
Class Dothideomycetes
Order Pleosporales
Family Pleosporaceae
Genus Cochliobolus
Species heterostrophus
  • Bipolaris maydis
  • Helminthosporium maydis
  • Heliminthosporium maydis
  • Drechslera maydis
  • Ophiobolus heterostrophus
  • Southern corn leaf blight fungus
Characteristics related to biosafety
The southern corn leaf blight disease occurs in warm and humid tropical areas and in warm corn production areas including the USA. To date it has not caused any economic damage in mid-Europe.
Cochliobolus heterstrophus is found in many tropical regions and in the southern part of the US.
Causes the southern corn leaf blight disease.

The disease cycle of Cocholiobolus heterostrophus is cyclical and releases either asexual conidia or sexual ascospores to infect corn plants. The asexual cycle is known to occur in nature and is of primary concern. Upon favorable moist and warm conditions, conidia (the primary inoculum) are released from lesions of an infected corn plant and carried to nearby plants via wind or splashing rain.

Once conidia have landed on the leaf or sheath of a healthy plant, Bipolaris maydis will germinate on the tissue by way of polar germ tubes. The germ tubes either penetrate through the leaf or enter through a natural opening such as the stomata. The parenchymatous leaf tissue is invaded by the mycelium of the fungus; cells of the leaf tissue subsequently begin to turn brown and collapse. These lesions give rise to conidiophores which, upon favorable conditions, can either further infect the original host plant (kernels, husks, stalks, leaves) or release conidia to infect other nearby plants.

The term 'favorable conditions' implies that water is present on the leaf surface and temperature of the environment is between 60 and 80 degrees Fahrenheit. Under these conditions, spores germinate and penetrate the plant in 6 hours. The fungus overwinters in the corn debris as mycelium and spores, waiting once again for these favorable spring conditions. The generation time for new inoculum is only 51 hours.
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