Tan Spot (fungus - Pyrenophora trichostoma): Tan spots can occur on both leaf surfaces. Initial symptoms will be tan-brown flecks and the spots will enlarge into lens-shaped lesions. The fungus grows as a saprohpyte on crop residue. Because of this it has been observed to be more severe in no-till wheat. Cultural practices such as deep burial of straw and rotation will help reduce tan spot. Fungicides may be economical if the crop has a potential yield of forthy bushels or more per acre.