Wheat Stripe Rust Found In Tennessee

 JACKSON, TENN.
   Wheat Stripe Rust (Puccinia striiformis) has been found in West Tennessee. This rust is also called yellow rust and is very easy to identify because the individual pustules are lined up in conspicuous stripes or rows between the veins of the leaves. The rust pustules start out as very small yellow spots but quickly develop into rows of orange pustules (UT orange) many times extending the length of the leaf blade. All exposed leaves can quickly become infected almost at the same time. Individual infection sites in the field create yellow spots but quickly spread to all plants. Usually, we hear about stripe rust inLouisiana andArkansas and in most years it does not cause damage inTennessee. This year it could be a lot more severe. Recent rains and cool temperatures were ideal for infection and disease development.
   Resistance to stripe rust varies widely among wheat varieties from very susceptible to resistant. Since Tennessee has not experienced this disease to any great extent recently, I do not have a list of resistant and susceptible varieties.
    We know that this disease can move very quickly and can cause high yield loss on susceptible varieties. On resistant varieties, there may be no symptoms or pustules at all and spraying may not be necessary. Producers should scout their wheat fields now and if stripe rust is found they should consider spraying a fungicide now even if heads are still in the boot. If no stripe rust can be found, then a fungicide spray at flowering for the usual glume blotch and scab should be considered. All registered fungicides can be effective if application is made before rust gets too far along. If stripe rust is all over the leaves, spraying will do little good. The strobilurin fungicides are effective when applied before infection occurs on the upper two leaves. If stripe rust has already started in the field, then spraying a Triazole fungicide such as Propiconazole, Prothioconazole, Tebuconazole, or Metconazole would be better (list of wheat fungicides).
   The best time to spray for stripe rust is between flag leaf emergence and boot stage. Spraying too early is better than spraying too late. If weather conditions remain wet and cool a second application may be needed. Good coverage is a must with about 15 gallons of water per acre and a COC,NIS or spreader sticker could be added to the spray for better spread and coverage. Δ
 DR. MELVIN NEWMAN: Extension Plant Pathologist, University of Tennessee
Stripe rust found on the Experiment Station inMadison County. Stripe rust is severe in at least one field in Haywood County judging from a specimen brought to me, today. Let me know if you have any questions about this disease. P.S. take your hand lens when you go to the wheat field. (Identifying Rust Diseases of Wheat and Barley publication can be found on utcrops.com)