The best time of year to manage biennial and perennial weeds is in the fall. Hemp dogbane, ailanthus, poison hemlock are just the tip of the iceberg on the list of weeds effectively controlled now. If you need a refresher, or need to dive in to start learning, here are some resources to get you started in the right direction:
Plants of Concern to Livestock in Summer | Ohio BEEF Cattle Letter
Biennial and Perennial Weed Control is Best in the Fall | Ohio BEEF Cattle Letter
Get After the Weeds Yet This Fall | Ohio BEEF Cattle Letter
Pasture and Forage Weed Control; Mow or Spray? | Ohio BEEF Cattle Letter
Scout now for cressleaf groundsel in hayfields, or pay the price in May | Agronomic Crops Network
2020 Ohio Weed Control Guide (PDF)
2020 Ohio Weed Control Guide (Bound Book)