Blackleg scouting more difficult as time passes

Pre-harvest blackleg rating small

Pre-swath or immediately post-swath are good times to check blackleg severity. Checking more than a week after swathing makes it more difficult to identify blackleg because other decomposers will start to work on the plant, often masking whatever blackleg symptoms may have been evident.

Videos that will help:
Post-swath disease scouting video
Blackleg disease and resistance management