Wheat (Triticum aestivum)-Flag Smut

See:

Cause The fungus, Urocystis agropyri, which overwinters as spores on seed or in soil. It infects wheat before seedlings emerge. Spores may survive several years in soil.

Symptoms Gray to grayish black streaks on leaves in the late tillering stage. Streaks break open later and release masses of gray-black spores. After this, infected leaves look quite frayed. If the infection is heavy, plants may be severely stunted, may tiller excessively, and usually fail to produce heads.

Cultural control

  • Resistant varieties are available.
  • Rotate 2 years out of winter wheat.
  • Plant seed shallow (less than 1 inch) when soils cool in fall.

Chemical control Seed treatment is effective against seedborne and soilborne inoculum.

  • Dividend Extreme at 2 to 4 fl oz/100 lb of winter wheat or triticale seed and at 4 fl oz/100 lb of spring wheat. Do not graze green forage for 55 days after planting. See label for reentry restrictions.
  • Dividend XL RTA at 10 fl oz/100 lb of winter wheat seed. Do not graze green forage until 55 days after planting. See label for reentry restrictions.
  • Raxil MD at 5 to 6.5 fl oz/100 lb seed plus a dye. See label for reentry restrictions.