How Does Japanese Knotweed Spread?
Connections between Japan and the UK have been very productive for many years. We’ve got Japan to thank for precious commodities such as innovative electronics and reliable cars. And let’s not forget karaoke. However, there’s one thing that’s made its way to our island and that is Japanese Knotweed.
How Did Japanese Knotweed Find Its Way to the UK?
Victorian botanists visiting Japan were wowed by its beauty and it wasn’t long before well-to-do UK gardeners embraced it and it became a commonplace garden plant. As is the case with many gardening trends, people moved on and Japanese Knotweed found itself being discarded.
Japanese Knotweed is able to regrow from the smallest fragment of root and it wasn’t long before it took over.
Why Japanese Knotweed is such a Problem
It has the potential to grow at an alarming rate, as much as 10cm each day during the peak season. Its roots can grow out in a seven-metre radius.
If you try to remove it you run the risk of causing further spread. The best course of action is to seek the help of an expert to stem the spread.
Housing and land prices can be seriously affected if it is found growing on a property. In some cases, the drop has been as much as 40%.
It is not exposed to any controlling organisms (bacteria, fungi, and invertebrates) and has been able to spread unchecked, often to the detriment of natural species.
How Does Japanese Knotweed Spread?
Japanese Knotweed does produce flowers and seeds. In its native home seed dispersal is one of the ways it spreads, but in the UK, it is only on very rare occasions that it spreads this way. The reason for this is that only female plants were imported, which means any seed produced are sterile. Instead, it spreads by growing from the stem, the crown, or a rhizome.
It’s possible for new plants to grow from green stem nodes. This can happen if they are left in water or planted in soil.
The crown of a Japanese knotweed plant can survive drying or composting. As soon as the crown comes into contact with water or soil, it will send out new growth.
For Japanese knotweed to spread from the rhizome, the smallest piece is required. Just breaking the rhizome up into pieces stimulates it to produce new growth in the form of small buds. These buds then grow into a new plant.
In the UK, Japanese knotweed is most commonly spread via the dispersal of rhizome fragments. How does Japanese knotweed spread? It can happen in several different ways.
Dispersal of Japanese Knotweed Rhizome Fragments
It’s very easy for Japanese knotweed to be dispersed via shoes or clothes. It happens when people walk through an area that’s contaminated. It’s common for this to happen in areas where the land is being redeveloped or treated, which of course lead to an increase in human traffic. It gets picked up on the bottom of boots or shoes. Even tires can pick up fragments of the rhizome and carry them to a new area without knowing. Given enough space, time, and the right conditions (water and soil) these rhizomes will send out new growth.
Birds and other animals can also help to spread Japanese knotweed. If they eat the young shoots any stems of canes that pass through their digestive system could potentially send out new growth. They could also help to spread it if they have any plant matter lodged in their hoofs or stuck on their fur.
Is Cross-Breeding Possible?
There are only two other species of plant closely related enough to result in crossbreeding. Giant knotweed (Fallopia sachalinensis) and Fallopia japonica var. Compacta are both able to hybridise with Japanese knotweed. While it might be possible, it’s never the reason for it to spread. Seeds from a hybrid will not produce new growth.
How to Stop Japanese Knotweed Spread
As well as answering the question, how does Japanese knotweed spread, let’s look at what you can do to stop it.
A few methods of stopping Japanese knotweed have been proven to work if you want to stop it from spreading. However, it’s advisable to seek the help of a professional and their equipment in order to ensure success. Methods that are commonly used include the application of herbicides, excavating as much of the plant as possible, burning and then burying. Several layers of material will be used in order to prevent any shoots from growing, should there be any fragments of rhizome left.
Now you’ve got the answer to how does Japanese knotweed spread, you might be tempted to try a DIY method. But you can only guarantee a result if you call in the experts. An accredited treatment firm such as ours will be able to immediately treat the area and offer continued treatment to prevent any further growth. We are an approved member of the PCA Invasive Weed Group and also approved by the Royal Institute of Chartered Surveyors.