• Worldwide distribution. In tropics and sub-tropics. On sorghum and grasses. Occasional outbreaks have been serious. 
• Spots merge and cause leaves to dry and die. Spores on undersides of leaves spread in wind and rain splash.
• The blight survives in debris, and on 'volunteers'.
• In the 1970s, in the US and elsewhere, a strain of the fungus (Race T), caused an epidemic, and resulted in ear rot, ear drop and lodging, and a large loss of yield. Race O is the common strain in the tropics and causes minor crop loss.
• Cultural control: resistant varieties; remove volunteers; provide mineral fertilizers or manures; wide spacing to reduce humidity; collect trash at harvest, compost or feed to livestock; plough-in remains; crop rotation.
• Chemical control: only use if resistant varieties are not available (main control method); use chlorothalonil or mancozeb. Apply when spots first appear.

Southern leaf blight, southern corn leaf blight, southern leaf spot, maydis leaf blight

Cochliobolus heterostrophus; this is the name for the sexual stage; the asexual stage is known as Bipolaris maydis (previously it was Drechslera maydis and before that Helminthosporium maydis). There are different races.