See:
Fungicide Effectiveness as Seed Treatments for Cereal Diseases
Cause A fungus, Puccinia hordei (= P. anomala). Until recently, most varieties grown in the United States had resistance to leaf rust. Disease is promoted by moderate (59°F to 71°F) temperature and wet conditions.
Symptoms Round to oblong, light orange-brown pustules (uredinia) appear on leaf sheaths and blades, and later on heads of highly susceptible varieties. As the crop ripens, black spores (telia) are produced.
Cultural control
- Use early-maturing varieties.
Chemical control Seed treatments may reduce seedling infections.
- Raxil MD at 5 to 6.5 fl oz/100 lb seed plus a dye. See label for reentry restrictions.
Foliar applications can be made when the disease is severe.
- Demethylation-inhibiting (DMI) Fungicides (Group 3) are labeled for use.
- Bumper 41.8 EC or Bumper ES at 4 fl oz/A on a minimum of 14-day intervals for no more than two (2) applications, one (1) application maximum if harvesting for forage or hay. Do not apply within 45 days of harvest for grain and straw; 30 days for forage or hay. 12-hr reentry.
- Tebuzol 3.6F at 4 fl oz/A as a single application per season. Do not apply within 30 days of harvest. 12-hr reentry.
- Tilt at 4 fl oz on a minimum of 14-day intervals for no more than two (2) applications, one (1) application maximum if harvesting for forage or hay. Apply when the flag leaf is 50% to fully emerged, up to late head emergence (Feekes 10.5). Preharvest interval is 7 days for forage and hay. 12-hr reentry.
- Topguard at 10 to 14 fl oz/A on 7-day intervals. Preharvest interval is 0 days for forage, 15 days for hay, and 30 days for grain.12-hr reentry.
- Regalia (Group P5) at 1 to 2 quarts/A on 7- to 10-day intervals starting prior to infection. Under high-disease pressure, use in combination with another fungicide. Does not benefit from the addition of an adjuvant. 4-hr reentry. O
- Strobilurin fungicides (Group 11) are labeled for use. Do not make more than two (2) applications of a Group 11 fungicide per season. 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.
- Headline at 6 to 9 fl oz/A. Apply no later than 50% head emergence (Feekes 10.3). Preharvest interval is 14 days for hay and forage. 12-hr reentry.
- Quadris Flowable at 9 to 12 fl oz/A applied prior to disease development, up to late head emer gence (Feekes 10.5). Do not apply within 7 days of grazing. Preharvest interval is 7 days for forage and hay. 4-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.
- Miravis Ace (Group 3 + 7) at 13.7 fl oz/A. Apply between Feekes 10.3 and 10.5.4. Harvest interval is 7 days for forage and hay. 12-hr reentry.
- Priaxor (Group 7 + 11) at 4 to 8 oz/A. Do not apply after 50% head emergence (Feekes stage 10.3). Preharvest interval is 14 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 7 fl oz/A or Stratego YLD at 2.3 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 40 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 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 Group 11 fungicides. Preharvest interval is 7 days for forage and hay, 45 days for grain and straw. 12-hr reentry.