While it is a little early for a wheat disease update, here are a couple of pieces of time-sensitive information.

Fusarium Head Blight

A free webinar on Fusarium Head Blight will be hosted by the U.S. Wheat and Barley Scab Initaitve (USWBSI) on March 13th. The meeting offers 2 hours of CCA credits and will largely focus on fungicide applications for wheat scab. The event is free but you must register in advance. Fusarium Head Blight (FHB) is a disease that can cause yield loss, reduced test weights, and reduced seed quality in wheat.

Stripe Rust

Stripe rust of wheat was confirmed very early this year in Louisiana. This is something to keep an eye on over the next few weeks. The disease cannot survive Missouri winters, and spores of the pathogen (Puccinica striiformis f. sp. tritici) must be transported from the southern US for stripe rust disease to develop in Missouri wheat. Early infection prior to or at the flag leaf stage can result in substantial yield losses when conditions are favorable and a susceptible cultivar is planted. Overnight temperatures between 50 and 60°F favor disease development especially when heavy dew or irrigation are present. Infection slows as minimum air temperatures rise above 73°F.

Stripe rust gets its name from the characteristic pattern of yellow to orange pustules that develop parallel to leaf veins after tillering and result in the characteristic stripes (Figure 1). Prior to tillering, pustules develop in a random pattern on leaf surfaces.

Figure 1 Stripe rust on Missouri wheat. Image by Kaitlyn Bissonnette

If stripe rust is detected in your region this spring, consider a fungicide application for susceptible wheat varieties if forecasted conditions are favorable for the disease. Fungicide applications at flag leaf emergence help reduce yield losses. This is earlier than optimal applications for wheat scab but may be necessary. In some instances, a second application for stripe rust may be warranted. Fungicide efficacy is estimated to last 21 to 28 days and new growth will not be protected following application. Wheat fungicide efficacy charts are available on the Crop Protection Network. For sample confirmation, please consider submitting symptomatic plants to the MU Plant Diagnostic Clinic.