Good Morning,
If you want to remove giant hogweed, be sure to take appropriate precautions to prevent exposure to giant hogweed’s sap by wearing protective coveralls, rubber gloves, eye protection and sturdy shoes. Place plant parts in heavy duty garbage bags. Do not mow, cut or weed-whack to try to control the plant
mechanically. Its large perennial root system will soon send up new growth.  Also, these tactics are risky because they increase the opportunities for you to come in contact with the plant’s sap.
Small seedlings can be controlled with a labeled herbicide containing glyphosate, but most references state that a mature giant hogweed plant will not succumb to a single application. Controlling with a herbicide will require close attention, reapplication to basal sprouts and a keen eye for germinating
seedlings, which can germinate for several seasons. Anyone using a herbicide to control giant hogweed must do so according to pesticide label directions

giant_hogweed_(e2935).pdf (msu.edu)
Cowparsnip: A common look-alike to giant hogweed - MSU Extension
Common plants are being mistaken for giant hogweed - MSU Extension

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