Using Fungicides to Suppress Fusarium Head Scab in Wheat

The wet weather this spring has greatly elevated the risk of Fusarium head scab. At this point, the use of a fungicide at flowering is the best response for trying to curb the disease and suppress its associated mycotoxin (a.k.a. DON or vomitoxin). A fungicide application at the flowering stage offers the added benefit of helping keep leaf diseases in check.

Head scab is favored by moderate temperatures (56 to 86 degrees Fahrenheit) and high relative humidity (particularly in excess of 90%) around and during the flowering stage. Michigan State University Extension recommends utilizing the Fusarium head scab risk assessment tool. This prediction model provides a daily level of risks for specific locales. For southern Michigan where wheat is heading, the model is suggesting some of the highest risks levels that we have seen in recent years. For those in central Michigan where the flowering stage may still be a week away, the level of risk may be significantly less or even low depending on weather. The model is correct most of the time, but growers are also encouraged to rely on their knowledge of localized environments and their own experience.

Another important consideration is the innate resistance level individual varieties possess to fend off the disease. Below is a table providing a list of some common, established varieties and their respective resistance rating. Another good source of information is the Michigan State Wheat Performance Report.  Table 3 of this updated report provides the resistance ratings for varieties from the 2018 season.

Relative susceptibility of winter wheat varieties to Fusarium head scab