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:
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