Michigan Wheat: Fusarium Head Scab – Fungicide Considerations

This season, wheat disease levels have been relatively low due to the cool spring. However, now that temperatures have warmed and some areas have received lots of rain, it’s time to consider using a fungicide to curb fungal diseases common to wheat. A fungicide application during the flowering stage should target Fusarium head blight (or head scab) while recognizing that the treatment can be equally important in curbing foliar diseases that tend to develop on flag leaves during June.

Head scab is favored by moderate temperatures of 56 to 86 degrees Fahrenheit and high relative humidity, particularly in excess of 90 percent, around and during the flowering stage. Michigan State University Extension recommends utilizing the Fusarium Risk Assessment Tool. It provides a daily risk assessment for specific locales. The model is correct about 75 percent of the time, but growers should also rely on their own experience. Another consideration is the innate resistance individual varieties have to fend off the disease (see table).

Ground application is generally recommended for applying wheat fungicides. However, aerial application of fungicides may be necessary where wet conditions prohibit ground rigs from operating. Aerial application may have reduced head deposition compared to ground rigs, but still can offer significant protection against head and leaf diseases.

The best fungicides for head scab include Prosaro and Caramba. These products usually reduce the severity of the disease and the associated mycotoxin (D.O.N. or vomitoxin) level by half if applied correctly. To optimize the benefit of these fungicides, treat two to seven days after the heads have begun to flower. An information piece from MSU, “Managing Fusarium head blight,” is available as a resource.