Madam, - It's not only to knotweed the authorities are turning a blind eye (August 17th).
Doubtless knotweed is a noxious weed but there's an even worse one - ragwort - that is now covering virtually the entire country.
As far back as the 1930s ragwort was recognised as being seriously poisonous to cattle and other animals.
For over 70 years it has been illegal - and still is - to have ragwort on one's property.
Back in the mid-20th century it was a serious offence to be found with it.
In those days fines were heavy and were applied ruthlessly to anyone found with the weed; so why not today?
State authorities and local governments should be more assertive about carrying out their legal responsibility to ensure that this dangerous weed is eradicated before it ruins our agriculture. - Yours, etc,
DAVID SOWBY, Knocksinna Crescent, Dublin 18.