What kills Giant Knotweed?[2013]

We will investigate what kills Giant Knotweed ? and look at the differences between Giant knotweed and Japanese knotweed. They are both invasive plant species. They belong to the same family, Polygonaceae. Furthermore they share some similarities. However, there are a few key differences between them:

  • Taxonomy: Giant knotweed is known scientifically as Fallopia sachalinensis. Japanese knotweed is known as Fallopia japonica. They are two different species within the same genus.
  • Size: Giant knotweed generally grows larger than Japanese knotweed. Giant knotweed can reach heights of up to 15 feet (4.5 meters) or more. Japanese knotweed usually grows to about 6-10 feet (1.8-3 meters) tall.
  • Leaf Shape: The leaves of giant knotweed are generally broader and more heart-shaped. Compared to the narrower, somewhat elongated leaves of Japanese knotweed.
  • Stem Colour: The stem of giant knotweed is typically reddish-brown or dark brown. Japanese knotweed’s stem is usually green with purple speckles.
  • Habitat: Giant knotweed is native to Sakhalin Island in the Russian. Additionally Far East and is commonly found in northern regions, including parts of Asia, Europe, and North America. Japanese knotweed, as the name suggests, is native to Japan but has spread to various other parts of the world, including Europe, North America, and New Zealand.

Both giant knotweed and Japanese knotweed are considered highly invasive species.

  • Invasiveness: Both giant knotweed and Japanese knotweed are considered highly invasive species. However, Japanese knotweed is generally considered more problematic and widespread in its invasiveness. Its ability to spread rapidly and persistently through rhizomes (underground stems) makes it particularly difficult to control.
  • Chemical Control: Using herbicides, can effectively kill Japanese knotweed. However, it may take multiple applications over several years to fully eradicate the plant. It’s important to use the herbicide according to the label directions and consider the surrounding ecosystem, as it could have an impact on other plants.
  • Physical Control: Cutting or mowing the plant can help to slow its growth, but it will not kill the roots. Repeated cutting can weaken the plant over time, but it is not a long-term solution.
  • Biological Control: The use of insects or pathogens that are specific to Japanese knotweed can be used to control its growth. However, this method is still in the research phase and not yet widely available.
  • Excavation: This method is the most effective, but also the most expensive and disruptive. The entire plant, including the roots, must be removed and disposed of properly to prevent regrowth.

It is important to note that killing giant knotweed is a long process and it’s important to stay vigilant as it can regrow from small fragments of roots or rhizomes.

Best not to cut Giant Knotweed

furthermore if Giant Knotweed (Fallopia sachalinensis) is cut aboveground, the rhizomes (underground stems) of the plant can utilize nutrient stores to send up new shoots. Giant Knotweed is known for its aggressive growth and reproductive capabilities through its extensive rhizome system. Cutting the aboveground growth may temporarily suppress the plant, but the rhizomes can remain active and initiate the growth of new shoots when conditions are favourable.

The nutrients stored in the rhizomes of Giant Knotweed are primarily carbohydrates and starches. These substances serve as energy reserves that the plant can utilize to support new growth when the aboveground portion of the plant is cut or damaged. The rhizomes store these nutrients to sustain the plant during periods of dormancy or when resources are limited. By tapping into these nutrient stores, the plant can allocate resources for the production of new shoots and leaves, allowing it to regenerate and continue its growth cycle.

Induce dormancy

it is possible to induce dormancy in plants, including Giant Knotweed, by applying excessive amounts of herbicide. Herbicides are chemical substances specifically designed to kill or inhibit the growth of plants. When applied in high concentrations, herbicides can have a detrimental effect on the overall health and growth of plants, potentially leading to dormancy.

Excessive herbicide application can disrupt the normal physiological processes of a plant, causing damage to its tissues and interfering with its ability to photosynthesize and obtain essential nutrients. In response to the stress caused by the herbicide, plants may enter a state of dormancy as a survival mechanism.

However, it’s important to note that inducing dormancy through excessive herbicide application may not always be desirable or effective for long-term control of Giant Knotweed. While it may temporarily suppress the growth of the plant, the rhizomes can remain viable underground and initiate new growth when conditions become more favorable.