Using fungicides to suppress Fusarium head scab in wheat
As wheat begins to head, growers will need to decide whether to apply a fungicide to combat Fusarium head scab.
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. This 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 and that of local consultants.
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 within a week of when half the heads are hosting at least one flower (anther). The MSU Extension tip sheet, “Managing Fusarium Head Blight,” is available for more complete 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. During the 2016 season, it is important growers consider stripe rust in the mix of foliar diseases that can threaten the crop as it is particularly prevalent this season and some Michigan varieties are relatively susceptible.