Japanese Knotweed

Japanese Knotweed is never out of the news for long, and we get regular enquires from very anxious people asking for our help. We have been eradicating Japanese Knotweed for many years now and we have acquired an intimate knowledge of the pernicious plant. Fully understanding its botanical traits is crucial to its successful control.

Japanese Knotweed (Fallopia japonica) is a non-native herbaceous perennial plant which first arrived in the UK in the 1800’s. It was being grown on British nurseries by the mid-1870’s and sold as an ornamental screening plant. However, it fell out of favour but remained growing in small isolated urban and sub-urban areas of the UK. With the growth of commerce in the Victorian era Japanese Knotweed began to spread. It was thought initially via the canal system, then latterly via the railways. The distribution of soils as a result of the building booms of the late 20th century caused a massive increase in its spread. Japanese Knotweed has no natural predators in the UK such as insects, fungi or bacteria; it has therefore grown largely unchecked.

There are now strict laws in UK which are designed to protect the environment from non-native invasive species. Anyone causing the spread of Japanese Knotweed or allowing it to grow on anyone else’s property can be prosecuted or given a community protection notice for causing a nuisance.

The only way to treat it safely and successfully is to survey the infestation and draw-up a documented eradication plan. Timing of treatments is a key factor, as is the choice of herbicides used and the environment where the plant is growing. Successful treatment can take from three to five years depending on the type of infestation, but our experience is that it can often be dealt with within two years.

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