County councillors issued a warning that the Government needs to act against it now before it is too late.
The claim was made at the Western Division municipal authority after it was highlighted that Skibbereen had been “almost enveloped” the plant.
The plant’s growth had become so serious in Britain that the government had set aside £2bn to tackle the problem, the council heard.
Cllr Joe Carroll (FF), who lives in Skibbereen, said the Government must act to tackle the problem before it gets out of control.
Although he was aware of pockets of the plant in other parts of the county and country, he said he was horrified to see the extent of it in Skibbereen.
Mr Carroll said he had taken a tour of the town with a knowledgeable person who was able to identify areas where Japanese knotweed had infested.
The list, he claimed, included Schull Rd, New Cemetery, the Abbey Cemetery area, Upper Bridge St, Flax Hill, Riversdale, Baltimore Rd, Lough Ine Rd, Castletownsend Rd, High St, Coom Rd, Dealish Pier, Enda O’Donovan’s roundabout, and the town car park.
Mr Carroll said that if spores from the plant came in contact with parked cars the knotweed could be carried even further afield.
“It’s like a jungle in places. If it gets into housing estates it will devalue the properties — at the very least — and more urgency is needed to tackle it,” he said.
Mr Carroll said that he understood Offaly County Council had a scheme in place to tackle the plant and asked council officials to investigate.
Severing or damaging the plant causes the spread of spores and this was strongly advised against, he said.
Cllr Noel O’Donovan (FG) said he had recently witnessed a farmer doing his civic duty by cutting roadside hedging, but was unaware that it contained a number of Japanese knotweed plants. Therefore, he was likely to have inadvertently spread the problem further afield.
Mr O’Donovan said Kerry County Council had erected signs in areas of Japanese knotweed infestation advising people not to cut the plant.
Cllr Michael Collins (Ind) said he was very concerned the plant was growing up sides of houses in Kilcrohane in the Sheep’s Head peninsula.
“The British government is allocating £2bn to tackle it. That’s how seriously they are taking it,” Mr Collins added.
Aidan Weir, the senior council engineer, said, in reality, the responsibility for tackling the plant rested with the National Parks and Wildlife Service.
He acknowledged that there was a need for a public awareness programme about the damage the plants could cause, but said it had to be tackled by a multi-agency approach.
“We’re identifying it [in areas]. The treatment isn’t such a difficult job, but it has to be treated for three successive years with a weedkiller product like Roundup. Cutting it is lethal,” Mr Weir said.