Wheat (Triticum aestivum)-Stem Rust {Black Rust}

Note how the dark red lesions have ripped these stems.
Note how the dark red lesions have ripped these stems.

See also:

Cause A fungus, Puccinia graminis, that overwinters as black weather-resistant spores (teliospores) on wheat stubble and straw. Alternate hosts are species of barberry (Mahonia sp.). It may overwinter as mycelium of the uredinial stage on early seed or on volunteer wheat or grasses.

Symptoms The red rust, or summer spore, stage appears on leaves and stems as elongate pustules (uredinia) containing reddish brown spore masses. The black rust or autumn spore stage (teliospores) is similar except for color.

Cultural control

  • Eradicate the alternate host, barberry.
  • Cultivars, planting dates, and herbicides that delay maturity may make the crop more vulnerable to the disease.

Chemical control

  • Demethylation-inhibiting (DMI) Fungicides (Group 3) are labeled for use.
  • Bumper 41.8 EC at 4 fl oz/A. May be applied until Feekes growth stage 10.5. Do not treat within 30 days of harvest for forage or hay. 12-hr reentry.
  • Folicur 3.6F at 4 fl oz/A as a single application per season. Do not apply within 30 days of harvest. 12-hr reentry.
  • Proline 480 SC at 4.3 to 5.0 fl oz/A on 14-day intervals. Preharvest interval is 30 days. 48-hr reentry.
  • Tebuzol 3.6F at 4 fl oz/A at flag-leaf emergence up to the end of flowering. Do not apply within 30 days of harvest. 12-hr reentry.
  • Tilt at 4 oz/A at flag-leaf emergence (Feekes stage 8) but no later than Feekes 10.5. Do not apply within 7 days of harvest for forage or hay. 12-hr reentry.
  • JMS Stylet-Oil at 1 to 2 pints/A. Up to three (3) applications can be made starting when the first node of the stem is visible (Feekes 6) through the end of flowering (Feekes 10.5). Do not spray if foliage is wet or if the temperature is below 32°F, above 90°F or when plants are under heat or moisture stress. 4-hr reentry. O
  • Strobilurin fungicides (Group 11) are labeled for use. Do not make more than one (1) application of a Group 11 fungicide before alternating to a labeled fungicide with a different mode of action.
  • Aftershock at 2 to 4 fl oz/A on 14- to 21- day intervals up to late head emergence (Feekes 10.5). Make no more than one (1) application prior to harvest of wheat forage. Do not apply within 7 days of harvest for forage and hay; 40 days of harvest for grain and straw. 12-hr reentry.
  • Headline at 6 to 9 fl oz/A. Apply no later than the end of flowering (Feekes 10.5). Do not harvest wheat hay within 14 days of last application. 12-hr reentry.
  • Quadris Flowable at 4 to 12 fl oz/A up to late head emergence (Feekes 10.5). Do not apply within 14 days of harvest for forage and hay; 45 days of harvest for grain and straw. 4-hr reentry.
  • Vertisan at 10 to 24 fl oz/A on 7- to 14-day intervals through flowering (Feekes 10.5.1). Do not make more than two (2) sequential applications before alternating to a labeled fungicide with a different mode of action (non-Group 7). Preharvest interval is 0 days for forage and hay. 12-hr reentry.
  • Premixes of Group 3 + 11 fungicides are available for use. Do not make more than two (2) applications per season.
  • Quilt or Quilt Xcel at 10.5 to 14 fl oz/A when the flag leaf is 50% to fully emerged. Applications may be made no closer than a 14-day interval and may be applied up to Feekes growth stage 10.5. Preharvest interval is 30 days for forage and hay. 12-hr reentry.
  • Stratego at 10 fl oz/A. Do not apply after flag-leaf emergence (Feekes stage 8). Do not apply within 35 days of harvest. 12-hr reentry.

Biological control

  • Ballad Plus at 1 to 4 quarts/A on 7- to 14-day intervals. Can be applied up to and on the day of harvest. 4-hr reentry. O