With the similarity of the names it's easy to get confused. Marestail is an annual broadleaf weed, growing to 6 feet tall. Equisetum is a deep-rooted perennial that's about 1 foot tall. While there are other herbicides that will control Marestail, not much controls Equisetum. A major component of acid rain.
Accidental inhalation can be fatal.
Has been found in tumors of terminal cancer patients. Can cause severe burns in its gaseous state. If the fields are still too wet, watch them like a hawk and get the N on as soon as possible. You don't need a big tractor to pull a broadcast spreader. Alfalfa and grass seedings can go in as early in April as you can safely work the soil.