A destructive plant, known for wreaking havoc on homeowners, has been spotted in Helensburgh.

Japanese Knotweed grows up to three metres tall and its roots can reach down to 20 metres underground. 

While it hibernates over Winter, from March and April it returns and can destroy pipework, drains and can even weaken building foundations.

But the invasive plant specialist Environet UK, is here to help, revealing the number of Japanese knotweed hotspots across the county this spring.

Environet UK's interactive online tracker, Exposed: The Japanese Knotweed Heatmap was designed to inform homeowners and homebuyers of the presence of the destructive plant and the risk to their property.

The data is generated from over 50,000 known infestations and it adds new sightings daily.

Here are the hot spot areas you should be aware of, how to spot Japanese Knotweed and how and why you should deal with it.

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Japanese Knotweed spotted in Helensburgh

Helensburgh Advertiser: Japanese Knotweed spotted in Helensburgh. Credit: EnvironetJapanese Knotweed spotted in Helensburgh. Credit: Environet

In Helensburgh alone, there are 45 occurrences within 4 km with 49 occurrences recorded by Blairvadach along Gare Loch.

There are 25 cases recorded in that range in Cardross.

Nearby Balloch is also a hotspot for the plant, there have been 28 cases recorded within that range near Loch Lomond.

Meanwhile, Rosneath has had 18 occurrences within 4 km.

How to spot Japanese Knotweed

Not only is Japanese Knotwood notorious to get rid of but it is also tricky to spot.

Its appearance changes with the seasons so you need to be aware of what the plant looks like at different times of the year.

Euronet says that it is easier to spot Japanese knotweed during the spring and summer months.

These are the key traits you should be looking out for:

  • Red shoots emerge in spring that look like asparagus
  • Leaves which are shield or shovel-shaped
  • Stems that resemble bamboo canes with purple speckles
  • Small, cream-coloured flowers developing towards the end of summer

In contrast, as we move into Autumn later in the year, you should look for yellowing leaves that wilt as we head into winter.

The stems will also change to a darker brown before it becomes dormant in winter.

Japanese Knotweed is often mistaken for other plants including Bindweed, Himalayan balsam, Russian vine and more. 

You can learn more about how to identify Japanese knotweed via the Environet website.

How to deal with Japanese Knotweed

Japanese Knotweed has a powerful root and rhizome system that extends deep into the ground, making it extremely difficult to treat and remove by yourself.

Environet encourages you to get professional help to treat the tricky plant because failure to remove can lead to your property being damaged and even devalued.

Due to the plant's harmful side, it is listed as a defect to the property by RICS Homebuyer Reports and could take a 5-15 % decrease in the property's value.

Environet has identified three solutions for controlling and getting rid of Japanese Knotweed, they are as follows:

  • Physical Removal - Excavation and removal of the underground root and rhizome system, ensuring Japanese knotweed is gone, and gone for good.
  • Herbicide Treatment - Is a control method, as while herbicide can kill immature plants, it’s less effective on mature rhizomes, often causing dormancy rather than death.
  • Combination Methods - A combination of physical removal, herbicide treatment and the use of root barriers is often the optimum solution.

The invasive plant specialists have also put together advice and guides for commercial and resident properties and have answered all your key questions via the Environet website.