Fungicide Timing for all Grain Classes

Favorable environmental conditions may allow scab development over a wide window following head emergence of small grains. However, fungicides can’t be applied too late in the growing season, because each fungicide has a pre-harvest interval that prohibits later application. The shortest preharvest interval for registered fungicides is 30 days. Research has shown that the optimal timing for fungicide application under current registration laws is:

Spring/Winter Barley
Optimum time to apply a single fungicide for scab and DON reduction in spring barley is at early full head emergence, equal to Feekes 10.5. Later applications in barley also may be successful, if barley prices and fungicide prices allow economic application with two treatments. For winter barley, applications at early full head emergence (Feekes 10.5) and up to six days later are equally effective at reducing scab and DON.
Durum Wheat
Optimum time to apply a single fungicide for scab and DON reduction is at early flowering, equal to Feekes 10.51. However, durum has a long window of vulnerability to infection, from early flowering (Feekes 10.51) through kernel watery ripe stage (Feekes 10.54). Because of that, a slightly later application than early flowering may be feasible, if environmental conditions are more favorable for disease development just past flowering.
Hard/Soft Spring Wheat
Optimum time to apply a single fungicide for scab and DON reduction is at early flowering, equal to Feekes 10.51. Applications prior to this growth stage have not adequately reduced scab severity or DON.
Hard/Soft Winter Wheat
Optimum time to apply a single fungicide for scab and DON reduction is at early flowering, equal to Feekes 10.51. Equivalent benefit may occur from applications up to six days later.

Further information:

Visit the North Dakota State University factsheet.

Other Growth stage links:
North Dakota State Best Management Practices

Texas A&M Growth Stages

UMN Small Grains