What is the best way to get rid of milkweed in a hay field?

The best way to get rid of milkweed in a hay field is by mowing the field regularly to prevent the milkweed from flowering and setting seed. Additionally, you can consider using a targeted herbicide that is effective against milkweed while being safe for the surrounding grasses. It's important to monitor the field regularly to catch any regrowth of milkweed early on.