Fusarium head scab continues to be Michigan's most challenging wheat disease. Michigan State University Extension recommends that growers consider using fungicides during wheat's early flowering stage of development when weather conditions are conducive for fusarium development and infection. A fact sheet is available on the MSUE field crop team web site for learning more about the disease and using fungicides.
The disease, in general, is favored by moderate temperatures (56 to 86) and high relative humidity (particularly in excess of 90 percent) beginning and ending several days on either side of early flowering. The national fusarium prediction model is available to give a daily risk assessment for specific locals. The model is correct about 75 percent of the time, so growers are also encouraged to consider their own experience and that of local consultants.
The best fungicides for reducing fusarium's threat to grain quality are Prosaro and Caramba. However, even these products may only reduce the infection level by 40 percent and the associated mycotoxin (D.O.N.) by approximately less than 50 percent. To optimize the benefit of a fungicide treatment against fusarium, growers should make sure to apply when wheat is in the early flowering stage. Depending on air temperature, this is usually two to five days after half of the heads have fully emerged above the flag leaf collar.
The application timing of early-flowering mostly targets Fusarium head scab. In practice, however, fungicide use at this time is equally important for the suppression of various leaf diseases, and it is because of this multiple threat that most Michigan wheat fields receive a fungicide after heading.