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

See:

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.
  • Varieties, planting dates, and herbicides that delay maturity may make the crop more vulnerable to the disease.

Chemical control

  • Badge SC (Group M1) at 0.5 to 1.8 pints/A on no shorter than 10-day intervals. Preharvest interval is 0 days. 48-hr reentry.
  • Demethylation-inhibiting (DMI) Fungicides (Group 3) are labeled for use.
    • Alto 100SL at 3.0 to 5.5 fl oz/A applied between Feekes Stage 8 and 10.5.1 Preharvest interval is 21 days forage and hay; 30 for grain and straw. 12-hr reentry.
    • 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.
    • Miravis Ace B at 4 fl oz/A at flag-leaf emergence (Feekes stage 8) but not after Feekes 10.5.4. Do not apply within 7 days of harvest for forage or hay. 12-hr reentry
    • Proline 480 SC at 4.3 to 5.0 fl oz/A on 14-day intervals. Preharvest interval is 30 days. 12-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 is labeled for use in Oregon (SLN OR-120011, SLN OR-120012). 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). Preharvest interval is 14 days for hay and forage. 12-hr reentry.
    • Quadris Flowable at 4 to 12 fl oz/A up to late head emergence (Feekes 10.5). Do not apply within 7 days of harvest for forage and hay and 14 days of grazing. 4-hr reentry.
  • Succinate dehydrogenase inhibitors (SDHI) fungicides (Group 7) are labeled for use and include the following fungicide as well as other formulations. SDHI fungicides should always be mixed with a DMI fungicide to avoid selection for fungicide resistance.
    • 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.
  • Premixed fungicides are available for use. Do not make more than one (1) application of any Group 11 fungicide before alternating to a labeled fungicide with a different mode of action.
    • Dexter Max (Group M3 + 11) at 2.1 lb/A on 7- to 10-day intervals. Applications may be applied up to Feekes growth stage 10.5. Preharvest interval for hay is Feekes growth stage 10.5, but no less than 26 days; grain and straw is 45 days. 24-hr reentry.
    • Dexter Xcel (Group M3 + 11 +3) at 48 fl oz/A. The single application may be applied up to Feekes growth stage 10.54. Preharvest interval is 30 days. 24-hr reentry.
    • Priaxor (Group 7 + 11) at 4 to 8 oz/A immediately after flag leaf emergence but no later than the beginning of flowering (Feekes 10.5). Preharvest interval is 7 days for forage and chopped feed. 12-hr reentry.
    • Quilt or Quilt Xcel (Group 3 + 11) 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. Do not make more than two (2) applications per season. Preharvest interval is 7 days for forage and hay. 12-hr reentry.
    • Stratego (Group 3 + 11) at 10 fl oz/A. Do not apply after flag-leaf emergence (Feekes stage 8). Do not make more than two (2) applications per season. Do not apply within 35 days of harvest. See label for grazing, forage, and hay restrictions. 12-hr reentry.
    • Trivapro (Group 3 + 7 + 11) at 9.4 to 13.7 fl oz/A beginning when the flag leaf is 50% to fully emerged, up through full head emergence. Do not make more than two (2) sequential applications of Trivapro or other Group 7 or 11 Group fungicides. Preharvest interval is 7 days for forage and hay, 14 days for grain. 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