Using fungicides to suppress Fusarium head scab in wheat

As wheat continues to develop heads across Michigan, growers will need to decide whether or not to apply a fungicide to combat Fusarium head scab.

Wheat head with flowers (note visible anthers). Photo by Martin Nagelkirk, MSU Extension.

Wheat head with flowers (note visible anthers). Photo by Martin Nagelkirk, MSU Extension.

Fusarium head blight, or head scab, continues to be Michigan’s most challenging wheat disease. Michigan State University Extension recommends growers consider using fungicides during wheat’s early flowering stage of development when weather conditions are conducive for its development.

The disease, in general, is favored by moderate temperatures of 56 to 86 degrees Fahrenheit and high relative humidity, particularly in excess of 90 percent, beginning and ending several days on either side of the early flowering period, which begins a few days after heading and continues for several days depending on air temperatures.

The Fusarium Risk Assessment Tool is available to give a daily risk assessment for specific locales. The model is correct about 75 percent of the time, but growers are also encouraged to consider their own experience. The other major consideration is the innate resistance individual varieties have to fend off the disease (see table).

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

The fungicide application targeting Fusarium head scab is also important in helping reduce yield losses from leaf diseases. Protection from these diseases, including leaf spots and leaf rust, during the flowering and grain fill periods often translates to several bushels of additional yield per acre.

Relative susceptibility of winter wheat varieties to Fusarium head scab
Soft white winter wheat Soft red winter wheat
 Ambassador Very suscetible  Pioneer 25R40 Susceptible  Branson Moderately suscetible  MCIA Roane Moderately suscetible
 Skeet Safety Very suscetible  Wellman 206 Susceptible  Red Devil Moderately suscetible  Pioneer 25R50 Moderately suscetible
 Jupiter Susceptible  Hopewell Susceptible  AgriMax 413 Moderately suscetible  Red Dragon Moderately resistant
 AC Mountain Susceptible  Shirley Susceptible  DynaGro  9223 Moderately suscetible  DF 112R Moderately resistant
 Aubrey Susceptible  DynaGro 9243 Susceptible  Pioneer 25R39 Moderately suscetible  Pioneer 25R25 Moderately resistant
 Pioneer 25W36 Susceptible  Pioneer 25R47 Susceptible  DF 105R Moderately suscetible  Agrimax 415 Moderately resistant
 E6012 Susceptible  Red Ruby Susceptible  Sienna Moderately suscetible  Steyer Hunker Moderately resistant
 Venus Susceptible  Pioneer 25R62 Susceptible  Rupp 907 Moderately suscetible  L334 Moderately resistant
 DynaGro 9242W Moderately suscetible  Whale Susceptible  Sunburst Moderately suscetible  Rupp 972 Moderately resistant
 Pioneer 25W43 Moderately suscetible  DF 109R Susceptible  DynaGro 9171 Moderately suscetible
 Syngenta 901 Moderately suscetible  Agrimax 438 Susceptible  AgriMax 444 Moderately suscetible
 Pioneer 25W31 Moderately suscetible  DF 045 Susceptible  DynaGro  9053 Moderately suscetible
 DynaGro 9353W Moderately suscetible  SC1342 Susceptible  DynaGro 9042 Moderately suscetible
 DynaGro 9522 Susceptible  Wellman 123 Moderately suscetible

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