A stripe rust epidemic is occurring across Northeast Texas. We observed widespread infection levels near Royse City on April 5. The most susceptible variety appears to be AgriPro Magnolia. We also observed moderate infection levels in Crawford and USG 3295. All of these varieties exhibited good resistance to stripe rust last year, so there appears to be a race change in the stripe rust pathogen, Puccinia striiformis. Terrell LA 841 and Pioneer 25R57 appear to be resistant at this point.
Since there has been a race change in stripe rust, we cannot accurately predict which varieties will be infected. There is no substitute for field scouting. Stripe rust usually first appears in isolated spots in fields that can be detected from the road, but not always. Sometimes the pathogen will infect the field uniformly, making a careful inspection necessary for disease identification.
Stripe rust (Puccinia striiformis) can be a devastating foliar disease that infects both hard and soft red winter wheat in this region. It can be much more damaging than leaf rust, as it occurs earlier and can destroy the flag leaves prior to the grain filling period. The first line of defense to this disease is resistant varieties. But when the rust races change over time, the “fallback” position is application of a foliar fungicide to protect yield during grain fill.
Unlike leaf rust infections, which start on the older leaves in the lower canopy and move predictably up the plant, stripe rust infections can move like “wildfire” across the uppermost leaves of the plants. It is imperative to apply the fungicide when the first signs of infection are observed.