Southern corn leaf blight

Southern corn leaf blight (SCLB) is a fungal disease of maize caused by the plant pathogen Bipolaris maydis (also known as Cochliobolus heterostrophus in its teleomorph state). The fungus is an Ascomycete and can use conidia or ascospores to infect. There are three races of B. maydis: Race O, Race C, and Race T; SCLB symptoms vary depending on the infectious pathogen's race. Race T is infectious to corn plants with the Texas male sterile cytoplasm (cms-T cytoplasm maize) and this vulnerability was the cause of the United States SCLB epidemic of 1969-1970 For this reason, Race T is of particular interest. While SCLB thrives in warm, damp climates, the disease can be found in many of the world's maize-growing areas. Typical management practices include breeding for host resistance, cultural controls and fungicide use. The primary host for Southern corn leaf blight is Zea mays, or maize, known as corn in the United States. Various types of corn with normal cytoplasm (N) are vulnerable to Race O. They have cytoplasmic resistance to the T-toxin of Bipolaris maydis (produced by Race T). The absence of a gene found only in plants with Texas male sterile cytoplasm is reason for this resistance. Corn plants with T-cms cytoplasm have maternally inherited the gene T-urf 13, which encodes for a protein component of the inner mitochondrial membrane. T-toxin acts on this portion of the mitochondria. In a similar manner, Race C is only pathogenic to hosts with cytoplasm male-sterile C. SCLB can also infect sorghum and teosinte.