When you are called to state active duty during an emergency or impending emergency, you receive per diem at twice the rate a federal active duty member of your grade and time in service would get. For state active duty that is training or other non-emergency response, you receive the same per diem as an active duty member of your grade and length of service. For radiological emergency preparedness events you receive twice your base pay plus all authorized allowances.
There is nothing to apply for. Payment follows from your state active duty orders; raise any pay discrepancy with your unit administrator or the Delaware National Guard pay office.
Your state active duty orders showing the type of duty and your grade and time in service.