Japanese Knotweed Myths, Misconceptions and Facts
There are many mistaken notion’s as to how you can control Japanese Knotweed and what is really the best course of action to take. Pouring salt, diesel, caustic soda, turpentine, fairy liquid on the plant or into the ground are just some of the common fallacies which appear to have gathered momentum over the years, whilst others may be considered as a mixture of being quite innovative, yet some would say, rather ridiculous.
As a starter, type ‘Japanese Knotweed Services / Eradication / Removal’ along with any name of a large city or region located within the UK into google and take a few minutes to check out some of your local contractor’s websites. Whilst some contractors are undoubtedly very professional, ethical and like ourselves, firm believers in telling the public exactly what Japanese Knotweed can & can’t do, there are sadly others who don’t share the same values. You may have noted assertions similar to the following:-
“It will grow through solid concrete”
“It can destabilise foundations”
“Has the potential to cause structural damage”
“Japanese Knotweed can damage buildings especially if left to grow unhindered for a number of years”
“This invasive plant can have such a dramatic effect on structures, foundations & concrete”
Just to make things clear and unequivocal, providing any previous groundwork / construction works have been completed correctly and to high standard, it is almost impossible for Japanese Knotweed to grow through a slab of solid concrete, nor will it ‘destabilise solid foundation’s’. Furthermore, incidents whereby the plant has a dramatic ‘negative effect’ on any ‘solid structure’ are few and far between.
True or false?
In some cases, treating newly emerging & unestablished Japanese Knotweed with an approved herbicide, MAY have such an impact, that it does not re-appear in the following years. However in the majority of cases, a repeated herbicide application programme over several years will be required. Conventional wisdom is that the longer the plant has been prevalent, the more difficult it will be for the herbicide to penetrate the crowns & rhizomes (root system). Whilst one or two precise applications of herbicide will cause disruption to the plants growth cycle, do not accept any assurances or guarantees from anyone, who claim to be equipped to eradicate any Japanese Knotweed via the herbicide method, within one year or growing season.