Time to weed out ragwort and Japanese knotweed


Summer Pests:The poet John Clare called ragwort "thou humble flower with tattered leaves, I love to see thee come and litter gold".

Ragwort, with its distinctive golden yellow star-shaped petals, is flowering at this time of year, creating a delicate canopy of flowers, especially along lanes and roads.

It's a pretty sight, but a hateful one to farmers for which it is a perennial scourge. The only word in John Clare's ode that farmers would agree with it is the word litter, for ragwort is indeed nature's litter.

Ragwort is one of the weeds singled out in the Noxious Weeds Order (1937) which seems like a quaint anachronism now - the last prosecution was in 1988 - but was once enforced with a vigour which befits its status as a toxic pest.

Ragwort is a killer which causes liver failure in animals and is particularly dangerous to horses. In England, the Oxfordshire branch of the British Horse Society has spent £4,000 (€5,900) on employing a team to remove it from the county's hedgerows and verges.

Closer to home, the Department of Agriculture has written to local authorities and the National Roads Authority (NRA) seeking their co-operation in the control of ragwort.

According to the Irish Farmers' Association National Environment Committee chairman Tom Dunne, the presence of ragwort on the sides of roadways is a problem for farmers which is far from being eradicated.

"The problem is that we have so much ground being broken on the edge of roads and motorways and this is attracting thousands of weeds which blow on to farmland.

"The NRA has assured us they are taking care of the problem and some county councils are doing their best, but they didn't do it in a lot of places because I still see a lot of yellow appearing."

Another prolific pest is the Japanese knotweed, which as the name suggests is not native to these shores, but behaves as if it is. It was introduced to the British Isles during the 19th century during that era's craze for exotic plants. It spread from the ornamental gardens of large houses and estates to the surrounding countryside.

This plant forms dense thickets along roadsides, waste-grounds and waterways and can be distinguished at this time of year by its white flowers. It has no natural predators and will bully any plant that gets in its way.

A study carried out by NUI Galway into the prevalence of Japanese knotweed, which was supposed to be confined to Co Galway, elicited inquiries from all over the country. "We had a huge response from the public," said Elaine O'Riordan from the Centre for Environmental Science in NUI Galway.

"All over the country people wrote to us or rang us and said that they had the pest and asked how could they get rid of it.

"We found a lot of it is beside roadways and rivers and it does seem to be spreading, especially from material that was dumped or possibly came from around a quarry. The banks along the Corrib near the university are absolutely choked with it.

"Only a very small piece the size of your finger can start a whole colony.

"It's not an enormous pest yet, but it has huge potential. It has no natural predators in Ireland. It's far worse in England and Wales where they treat it as a toxic waste."