Bracken control is an example of the difficulty of deriving the right approach when it comes to chemical sprays. Bracken Encroachment is a problem and where a tightly controlled gazing regime cannot be used, or the ground is too steep for machinery, spraying is the only tool left (aerial spraying was banned nearly 10 years ago). The weed is carcinogenic to ruminants and harbours ticks and research suggests it may poison water courses(as do the sprays used for control)
Finding a solution to this problem that satisfies all is a challenge.
Areas of bracken on a farm are subtracted from the area eligible for farm payments under CAP.
Having first battled bracken in the late 70's I have a slight appreciation of all sides of the argument.

http://www.dwi.gov.uk/research/completed-research/reports/DWI70-2-237.pdf


http://www.brackencontrol.co.uk/

https://www.irishtimes.com/news/environment/farmers-weapons-of-mass-destruction-carry-cancer-fears-1.3148492