Regular farrier appts (ideally every 6 weeks), I have successfully treated seedy toe with x2 daily applications of iodine spray. Make sure the hoof is not left is damp, wet or muddy conditions for a prolonged period of time (which can be hard if the weathers anything like today!).
Tom had a seedy toe, my blacksmith came out every 6 weeks to clean it up. Now it is small enough for him to fill, I am hoping the next visit it should all be gone. My blacksmith said to keep it really clean and not to cover it up. Good luck