Cause A fungus, Puccinia striiformis (syn P. glumarum), which may oversummer on volunteer or early fall-seeded wheat and certain wild grasses (Aegilops, Agropyron, Elymus, and wild Hordeum spp.), and sometimes cultivated barley. The fungus overwinters as mycelium in leaf tissues, surviving down to at least 23°F, but spores can blow in from distant infections. Cool summers, mild winters, and long, cool, wet springs favor the fungus. Historically, 50°F to 64°F temperatures with intermittent rains or dews was optimal for disease development but new races of stripe rust appear to be adapted to warmer temperatures and are aggressively attacking hard red wheats in the Midwestern United States and overcoming high-temperature adult-plant resistance in winter wheats throughout the Pacific Northwest.
Symptoms Citron-yellow uredinia (spore masses) appear in long stripes on leaves and, rarely, on stems and heads. As the crop matures, black spores (telia) are produced in stripes, which are covered by the leaf epidermis.
- Most commercial winter wheat cultivars had good to excellent resistance, until 2004 when a new race appeared. Current ratings are available in extension and crop improvement association variety selection literature.
Seed treatments reduce seedling infections.
- Baytan 30 at 1.25 fl oz/100 lb seed plus a dye. Not registered for use in WA. 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.
Foliar applications can be made if disease is present and conditions are expected to remain favorable. Field scouting aids in detecting stripe rust early in the epidemic, while the disease still can be managed through fungicide applications. Once the crop is in the grain-filling stage, fungicide benefits are unlikely.
- 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.
- 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 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 more than two (2) foliar applications of Quadris or other Group 11 fungicide before alternating to a labeled fungicide with a different mode of action. 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.
- Ballad Plus at 1 to 4 quarts/A on 7- to 14-day intervals. Efficacy unknown in the Pacific Northwest. Can be applied up to and on the day of harvest. 4-hr reentry. O