Pests and Environment Southland

Fallopia japonica, commonly known as Japanese knotweed

one of the world's worst invasive species 

 
The invasive root system and strong growth can damage concrete foundations, buildings, flood defences, roads, paving, retaining walls and architectural sites. It can also reduce the capacity of channels in flood defences to carry water.


It is a frequent colonizer of temperate riparian ecosystems, roadsides and waste places. It forms thick, dense colonies that completely crowd out any other herbaceous species and is now considered one of the worst invasive exotics in parts of the eastern United States. The success of the species has been partially attributed to its tolerance of a very wide range of soil types, pH and salinity. Its rhizomes can survive temperatures of −35 °C (−31 °F) and can extend 7 metres (23 ft) horizontally and 3 metres (9.8 ft) deep, making removal by excavation extremely difficult.
The plant is also resilient to cutting, vigorously resprouting from the roots. The most effective method of control is by herbicide application close to the flowering stage in late summer or autumn. In some cases it is possible to eradicate Japanese knotweed in one growing season using only herbicides.


Classed as an unwanted organism in New Zealand.

 Straight from Wikipedia.  A right nasty pest plant indeed.  

And here we have an Environment Southland councillor apparently actively growing Japanese Knotweed.  Not bad for one supposedly educated and knowledgeable in matters green so he often tells all and sundry.  

mostly I use it to terrify pest-plant officers

To give the local bio-security officer conniptions by his own words.

Some might say one pest growing another pest.