Successfully Controlling, or even killing off, Japanese Knotweed
We realise that this is an unusual place for an answer to a gardening problem.
Japanese knotweed naturally grows on the volcanic slopes of mountain ranges in Japan. It was brought to the United Kingdom around 1825 to be an ornamental plant. However wherever it was planted it grew prolifically and over here there was nothing to keep its growth down like natural parasites or insects etc.
At Wallington Gospel Hall we had a problem of Japanese knotweed but we have probably killed it. For years it grew constantly and we tried to dig it out but without success.
Recently, however, we have been cutting the (hollow) stalks almost to ground level and putting two or three drops of a strong weed killer into each stem. This strategy has killed off the treated knotweed. If more knotweed grows we will certainly repeat the process.
We understand that with a larger scale problem this method would be time consuming. Nevertheless it would have long term beneficial effects.