Floral 'smiling assassin': National plan needed to combat rhododendron spread in Killarney

Rhododendrons are 'strangling the life' out of flora and fauna in places like Killarney National Park

Introduced in the 18th century here and native to Spain and Portugal, the rhododendron's lilac flower stands out in May and is often admired. 

A national plan is needed to combat the "smiling assassin", the rhododendron, which is strangling the life out of flora and fauna in places like Killarney National Park, an environmental group has said.

Friends of the Irish Environment (FIE) said the rhododendron, while beautiful and picturesque, is a "death warrant" to patches of the countryside that it invades.

Tony Lowes of FIE said that while the scourge of Japanese knotweed is becoming better known as a menace in communities, there is still a general lack of awareness about the "death sentence" that the pretty flower will pass upon nearby flora and fauna.

If rhododendron gets into a forest, it completely smothers the forest floor and allows for no regrowth. Young trees can't compete or grow up with that rhododendron. You will get neither regrowth or new growth. Your forest now has a death sentence hanging over it.

Rhododendron's spreading power is also of huge concern, he said.

While Japanese knotweed can grow at a frightening rate, rhododendron is even more insidious because it is carried on the wind, Mr Lowes added.

A bloom of Rhodendron Bushes in the gardens of Muckross House, Killarney.

"Tiny seeds go off in the wind and land anywhere. It's not like Japanese knotweed, which can only expand through its roots systems and so is contained. This thing threatens anything where the wind blows over," he said.

Because of the benign and appealing appearance of rhododendron, it was not seen as the clear and present danger that it should have been historically, Mr Lowes said.

Killarney National Park is one of the areas of beauty around the country that has been blighted by its grip.

Kenmare was one of the first regions for rhododendron, he said, when sea explorations brought the invasive species in the 17th century.

"They were seen as gloriously pretty, and soon became a favourite of Irish gardeners everywhere, who did an awful amount of damage without realising. 

"I've seen areas around Killarney where they have cleared it, apparently gotten rid of it, and within 10 years it is back to what it was. It is incredibly persistent and hard to get rid of," he said.

The key is to spot it when it starts, according to Mr Lowes.

The Vee in the Knockmealdown mountains covered in rhododendrons. 

He likened it to a flora version of Covid-19's spread, calling for a national campaign of containment, isolation and control.

"It's a bit like what we are seeing with track and trace. Whatever about trying to get what is already present out of here, we have to actually try and stop its spread and protect what is left," Mr Lowes said.

The National Parks and Wildlife Service (NPWS) is currently reviewing rhododendron and control measures in Killarney National Park, and has contracted an expert environmental firm.