Pacific Northwest 1998 An Online Guide to Plant Disease Control

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OSU Extension Office
 
Barley (Hordeum vulgare) -- Stripe Rust
 
Cause: The fungus Puccinia striiformis f. sp. hordei, is an obligate parasite that overseasons on volunteer barley or rye, certain wild barleys such as Hordeum jubatum (foxtail barley), wheat, and numerous perennial grass species. Wet winters with mild temperatures or abundant snow cover favor pathogen survival. It was first detected in the United States in 1991, in northern and eastern Idaho in 1993, and in Oregon in 1995. The disease begins from a very small number of infections that are difficult or impossible to detect in the field. Spread of the pathogen can be explosive and cause significant losses, especially in the Pacific Northwest where cool, wet weather greatly favors disease development.
Symptoms: Linear, orange-yellow pustules appear on leaves and/or heads at any growth state after infection. Pustules coalesce to form long stripes between leaf veins. In advanced stages, entire leaf blades of susceptible cultivars may be covered with pustules. The black spore stage develops as linear black pustules covered by the leaf epidermis.

Heavily infected plants starting to lodge.

 
Cultural control:

  1. Use resistant cultivars. The winter barleys ‘Kold’ and ‘Strider’ are resistant, and ‘Hundred’ may show somewhat reduced infection. Using cultivar mixtures or multilines may slow the rate of epidemic buildup. Spring barleys with some resistant are available: ‘‘Crest’ and ‘Orca’ are two-row feed barley; ‘Tango’ is a nondormant six-row; and ‘Sara’ is a six-row. ‘Baronesse’ has intermediate resistance and excellent yield potential.
  2. Plant winter cultivars as late as possible and spring cultivars as early as possible to help reduce the number of initial infections.
Chemical control: Scout barley regularly for rust, looking at lower leaves first. If conditions are cool and wet, inspect one more time, just before flag emergence.

  1. Use seed treatment in areas where barley stripe rust was detected the previous year, disease is expected to develop when plants are small, or when growing susceptible cultivars.
    1. Baytan 30 at 1.5 fl oz/100 lb seed. See label for reentry restrictions.
  2. Apply fungicides if stripe rust severity is greater than 5% at the late tillering stage. Applications made after flowering may not be economical. Scout fields weekly from mid-tillering to flag leaf emergence.
    1. Bumper 41.8 EC at 4 fl oz/A. Highest yields are normally obtained when applied to the emerging flag leaf. May be applied until the ligule of the flag leaf emerges (Feekes growth stage 8). Do not feed treated forage or cut green crop for hay or silage. 24-hr reentry.
    2. Headline at 6 to 9 fl oz/A. Begin applications in order to protect the flag leaf stage of growth from infection. Do not make applications later than 50% head emergence (Feekes 10.3). Do not harvest barley hay within 14 days of last application. 12-hr reentry.
    3. Quadris at 6 to 12 fl oz/A applied from jointing (Feekes 6) up to late head emergence (Feekes 10.5). Do not make more than two (2) foliar applications of Quadris or other Group 11 fungicides per acre per season. Do not apply within 14 days of harvest for hay. Do not apply within 45 days of harvest for grain and straw. 4-hr reentry.
    4. Quilt at 10 to 14 fl oz/A on a minimum of 14-day intervals. Can begin when the flag leaf is 50 to 70% emerged and continue up to Feekes growth stage 10.5. Do not feed treated forage or cut green crop for hay or silage. Crop tolerance/phytotoxicity notes on label. Preharvest interval is 45 days. 12-hr reentry.
    5. Tilt at 4 fl oz in not less than 15 gal/A water (ground) or 5 gal/A water (air). Apply when the flag leaf is 50% to fully emerged. Do not apply within 30 days of harvest for forage, 40 days for grain and straw and 45 days for hay. 12-hr reentry.
Biological control:
  1. 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.
References:

  1. Adams, E. B. 1997. Barley stripe rust. WSU Cooperative Extension Bulletin 1839.
  2. Mathre, D.E. 1997. Compendium of Barley Diseases. St. Paul, MN: APS Press.
  3. Web site: www.css.orst.edu/cereals/
Content edited by: Richard Smiley and Cynthia M. Ocamb on January 1, 2009
 
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