Photo by Sue Suchyta
Japanese knotweed, like that in the Rev. Ronald Iris’ back yard, is considered one of the worst invasive plant species in the eastern United States.
By SUE SUCHYTA
Sunday Times Newspapers
ALLEN PARK – Japanese knotweed is a deceptively pretty flowering plant that officials here are watching closely.
Valued by beekeepers, it’s a natural source of resveratrol, a natural compound that may protect against cancer and cardiovascular disease by acting as an antioxidant, antimutagen and anti-inflammatory.
However, when the Asian bush takes root in North America, it spreads quickly, crowding out native plants. It is difficult to eradicate and below the surface it is even more dangerous, as its roots can destroy foundations, pipes, roads and bridges.
Resident Peter Rolando gets along well with his neighbor, the Rev. Ronald Iris, whose land abuts his on the west border of his property. Rolando is concerned, though, with the aggressive spread of the Japanese knotweed that Iris planted along their common property line.
Iris’ transplanted knotweed already has begun to spread into Rolando’s yard. The plant, which can survive cold of minus 35 degrees Celsius (minus 30 degrees Fahrenheit) can extend 23 feet horizontally and 9.8 meters deep. Once the roots take hold, it is very difficult to dig up. It resists cutting and can re-sprout from the roots.
It can crowd out native species and now is considered one of the worst invasive species in the eastern United States. It is illegal to spread in the United Kingdom.
In Japan, Japanese knotweed is controlled naturally by a combination of fungus and insects. However, when it has no natural enemies in places like the United Kingdom and the United States, it overruns native species as it successfully competes for light, water and nutrients.
It spreads rapidly and is capable of exposing weaknesses in hard-engineered structures such as concrete, tarmac, brick walls and foundations. It also can damage flood walls and archaeological sites; reduce land values; and restrict riverbank access to fishermen.
The presence of Japanese knotweed has resulted in the refusal of a mortgage and delays from local planning authorities for construction projects until the plant is eradicated.
The giant herbaceous perennial grows up to 10 centimeters per day in any type of soil. It forms dense clumps up to 3 meters (10 feet) high. Japanese knotweed thrives on disturbance and spreads by natural means and by human activity. Very small pieces of the underground stems — the size of a penny — can allow the plant to regenerate and grow back.
It is below ground that Japanese knotweed causes the most damage. Each group of plants creates a rhizome network that grows downward, to 3 meters in depth, and 7 meters outward in all directions.
It threatens construction, since it can destroy and even grow through foundations, drains and other underground services.
City ordinance does not identify the species as a noxious weed, according to ordinance officer Pete Simakas, who looked into the situation at the request of City Councilman Frank Tucci.
David Boomer, community development director, said Tuesday he will issue a note to Iris and visit his property to look at the invasive species. He said the Ordinance and Building departments are working on it and will review their findings before deciding on a course of action.
Rick Lang, Department of Public Service director and city engineer, reportedly will look at possible impact of the weed on sewer pipes.