Using fungicides to suppress Fusarium head scab in wheat
Wheat fields are beginning to show signs of head emergence. This marks the time to consider applying fungicides to reduce the risk of head scab and leaf diseases.
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.
|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 susceptible|