Video: Kids play park in Cookstown surrounded by deadly Giant Hogweed

Stalks as high as 15ft have punched through fences on both sides of the Drum Road including into the play area beside Riverside Drive.

“The stuff is coming up out of the actual paths,” said Carol Connolly, the chair of the Riverside and Black Hill Community Group.

“I think they had to cut it down last week but it is quite overgrown - in some places it is the height of a person.

“It is not good to see it coming through the fence [into the kid’s play park], but thank goodness nobody has touched it yet.

“We would be very much in favour of keeping up efforts to cut it down.”

The plant’s sap produces severe skin burns in sunlight and can cause chronic effects including blistering and even blindness if it gets into a person’s eyes.

Burns can last for several months and some sufferers report that the affected area of skin remains sensitive to light for years afterwards.

Giant Hogweed growing from a fence close to the Black Hill playground

It flowers in mid-summer and seeds appear in late July. Seeds remain active in the soil for up to 10 years.

The plant’s dense foliage prevents light reaching the ground beneath. Other vegetation is killed off leading to rapid soil erosion.

“Giant Hogweed is totally alien to what we have here [in Tyrone],” said Ronnie Irvine, the press officer for Cookstown Wildlife Trust.

“The big landowners, maybe a century ago, brought plants in to embellish their estates.

Giant Hogweed plant growing beside a stream attached to the Ballinderry at Cabin Wood

“They brought Giant Hogweed in from the Caucausus region [Russia] as an ornamental plant and didn’t realise that it didn’t have any natural predator here. There was just nothing to keep it in check.

“It seems that the owners of Drum Manor brought it in there and it has gradually spread through the smaller rivers out of Drum and down along the Ballinderry where it has become quite a problem.

“The big problem with Giant Hogweed is the sap and if you get it on your skin and the sun strikes it will start a burning effect. You can get very severe burns which are very hard to shift and to stop.

“The Ballinderry River Enhancement Association tried to eradicate it, starting at its source at Drum Manor.

“They haven’t got very far but they have done quite a bit of work and a lot of spraying yet... it still continues for quite a bit down the river.”