The plant can cause severe, long-lasting burns and blindness in extreme cases. It can also cause severe injuries in animals. Dog owners are urged to be extremely cautious and pay particular attention if their animal is on a lead close to the river bank.
Volunteers combatting the growth of the plant have reported several cases on the banks of the rivers Nore and Barrow.
The volunteers and members of a sub-group of Keep Kilkenny Beautiful, the Invasive Species Eradication Group, are involved in organising the safe removal of the weed.
One man was injured while swimming last week at the Bleach Weir. He sustained a minor burn and is expected to recover fully.
Secretary of the Kilkenny Aqua Canoe Club Adrian Shanahan explained that it is a very difficult process to kill the plant.
“We have taken all the heads and blooms from the plants and have injected the stem where possible to kill it off,.”
“We have also geo-tagged where we think the seeds have fallen so we will be able to spray there in the spring before the plant gets the chance to grow,” he said.
“It can take up to seven years to get to that state so we need to be extra careful. The council has been very co-operative, but its resources are limited.
“Hopefully, it will be able to secure funding for us to help us eradicate the plant.”
Mr Shanahan also pointed out that the giant weed, which is innocuous in appearance, may put plans to develop the banks of the Nore as an official Blueway Trail in jeopardy.
The stretch of river is used for canoeing and paddling with walkers and cyclists making good use of the path that runs along the riverbank.
Blueway Trails is an initiative headed by Waterways Ireland, centred on outdoor activity along the environs of the waterways, and a feasibility study is being carried out on the Nore.
Meanwhile, there have been numerous reports of the poisonous weed on the Barrow and Kilkenny Water Safety has informed its lifeguards to be extremely vigilant.
Green Party councillor and environment spokesperson Malcolm Noonan said local authorities and statutory agencies remain ill equipped or resourced to deal with invasive species such as giant hogweed.
“While many of our introduced species have a relatively benign impact on human health or the environment, giant hogweed is a real threat. It can spread rapidly along riverbanks due to favourable growing conditions, spread of seed and the fact that the seed can remain dormant for up to 15 years,” he said.
“Management and control should be systematic and planned. Its presence in Kilkenny poses a real threat to the Nore as a public amenity and it is vitally important that a plan is developed with all agencies and local groups to eradicate it. Otherwise large tracts of the riverbank will become no-go areas.”