LAMAR, Mo.–  There are foliar diseases that can cause yield loss in winter wheat, said Jay Chism, an agronomy specialist with University of Missouri Extension in Barton County.

“It is important to scout wheat fields for diseases,” he said. “The key is to apply fungicides to wheat at the early boot stage to head emergence.” Applying fungicides at this growth stage, when the flag leaf is in danger of infection, provides the most benefit.

“So far, Septoria leaf blight is the primary wheat foliage disease showing up in most parts of the state,” said Laura Sweets, an MU Extension plant pathologist. “With the recent warm weather and rain, growers should be scouting for Septoria leaf blight, leaf rust, stripe rust and powdery mildew.”

As the crop moves into the late heading and flowering stages, Sweets added, the potential for Fusarium head blight or scab infection increases.

“Growers also should know the difference between viral and fungal diseases,” Chism said. Fungicides will have no effect on viral diseases.

“If fungal diseases are threatening to infect the flag leaf, then applying foliar fungicides is a good practice, but farmers need to identify the disease and the severity before they make that determination,” he said.

Severity of infection depends on the susceptibility of individual varieties to each of the diseases.

Delaying fungicide applications to coincide with insecticide applications may make economic sense. “Commodity prices are not as favorable as last year. Delaying an application of fungicides until an aphid threshold is reached may work in some instances,” he said.

Always follow the label recommendations when deciding to apply pesticides.