We all run rotations, which means changing from one crop to another, so when you are creating or editing a seed rate task you can show cropping information for the year you select at the top:
For example if you want to quickly select all the fields that were OSR last year, then change the year back to last year and 'Select All'.
You can also select the establishment scenario for the task in this dropdown:
Select the establishment layer before choosing the field and it will apply that layer to those fields. You can even mix establishments within the task.