There has been a great deal written about the vexed subject of Japanese Knot Weed, (JKW) or more correctly, Reynoutria japonica a.k.a Fallopia japonica or Asian Knot Weed. This native of East Asia was sold in nurseries and garden centres until the early 60s, when it was discovered to be simply too invasive for the United Kingdom climate.
In 1981 The Wildlife and Countryside Act included JKW as a plant that must not be planted, or allowed to grow in the wild. This meant that landowners were obliged to control the plant within the confines of their property, otherwise become liable for on-the-spot fines or prosecution. This Act was reinforced in 1990 by Part 2 of the Environmental Protection Act, now classified as Controlled Waste, to be disposed of only by Licensed means, by qualified, licensed and insured Waste Disposal Experts using transportation/burial methods.
It is widely held that the most effective control is Glyphosate. The plant is from a single female clone, and the seeds are therefore sterile. However the plant is extremely invasive and highly problematic once it arrives on site, often causing massive amounts of damage to structures and by blocking waterways.
I do not intend to produce a lengthy document regarding the methods of control, as these vary from site to site. Once identified in a garden site, the control will depend on a range of factors beyond the scope of a general article.
However, the purpose of this essay is to bring to the attention of the Garden Surveyor – whether Designer or Contractor – visiting a site with a view to producing drawings, plans, quotations, site evaluation documents as a Consultant, or any other reason that you may have been called in to assess a garden. (I do not recommend that you attend site to assess a potential infestation of JKW unless you are qualified and insured to undertake such works).
A recent study (January 2020) showed that over 5% of British Properties with a total value in excess of £5 billion pounds are affected by JKW. No assessment was possible regarding the cost of eradicating the problem, as there are too many factors involved regarding the degree and location of the infestation. Some plants will be growing freely in the grounds, whilst others will have affected foundations, buildings, drains etc.
Caution…..
The information shown above is well known, but as a Garden Surveyor (of whichever hue), you should be aware of your responsibilities to your client when it comes to assessing and surveying a garden site/property. Irrespective of your brief; either to measure, survey and assess a site prior to producing drawing and plans as a designer, or evaluating the costs involved in clearing, grading, terracing etc a site ready for landscaping.
YOU ARE THE PROFESSIONAL. You have been asked to attend site with a view to providing the customer with an end product. One that will be evaluated on the information you have gleaned from your visit. (There is a detailed Site Survey Assessment Guide available in the Landscape Library for use in all such situations).
You will be held liable and responsible in Law if you fail to properly assess the site, especially in respect of matters of pernicious weeds, dangerous situations and potential hazards. You cannot simply ignore a dangerous tree, a flight of steps that should be closed off from use, or a rotten handrail that you could not have failed to see when carrying out your survey.
In all such cases, a separate written note, highlighting the dangers as seen at the time, must be given to the client/owner/householder as soon as possible, with a copy for your own files, signed and dated as being submitted. This is your DUTY OF CARE.
If, during the survey, you believe you have seen EVEN A SINGLE PLANT, STEM OR LEAF of KJW, you must notify the customer, in writing, of your discovery. Even if it means that the operation has to be halted or abandoned (this situation should be covered in your Terms & Conditions) because of the discovery, all movement should cease. This is especially important during the growing season (April to October) when the JKW stems/leaves are green, as even the smallest part can be transferred on a boot or shoe to another part of the garden without being noticed.
A considerable part of my Consultancy work involves disputes and resolutions, and I recently had two calls from Solicitors to assist with sites where JKW had been discovered. Both sites had been inspected by qualified surveyors, who had completed their inspection forms, both finding no sign of JKW.
In the first case, the surveyor carried out their inspection in early April. There was no sign of any JKW noted, and no reason to suspect the presence of the plant. The plant dies off over the winter months, and if the dead stems are cleared, there is no visual sign above ground level. The surveyor duly noted that there was no sign (“none seen”) of JKW (a question requiring an answer is included in the survey document). The survey was carried out on behalf of a mortgage lender for the sum of around £500,000.
Three months later, standing tall and majestic, there is a stand of healthy looking JKW, three metres tall! My brief was to comment on the PROBABILITY of there being any sign of JKW at the time of the survey. My answer was that, JKW grows at a rate of 10 cm per day during the early growing season (April to May) and therefore, ten weeks later, it was perfectly possible for the plant to have reached ten feet tall, without being visible at the time of inspection. The value of the claim was for around £200.000 for excavation/clearance and loss of value on the house.
The case against the surveyor was dismissed. (As an aside on this story, the primary reason given by the Claimant for bringing the case was because the house was called Japonica Cottage. I pointed out that Japonica Cottage was a popular house/cottage name, used to celebrate Cydonia, Chaenomeles or Quince, especially in the 30s, 40s and 50s. Because of its name, the house must have been infested with Fallopia japonica for decades according to the Claimant!)
The second case also involved a surveyor. This time, the house was inspected during December, when the garden was very overgrown. This time however, the surveyor had written the word ‘Clear’ against the question/tick box titled Japanese Knot Weed. They had not seen any JKW in the garden, but they did not inspect BEYOND the garden. On all three sides of the (rear) garden, over the six foot high fences, dead stems of JKW could be clearly seen – in forests! The surveyors lost their case, and were found liable in the sum of over £30,000.00 for the excavation and removal of the plants.
Surveys should ALWAYS include neighbouring gardens and sites. Indeed, Surveyors should always inspect a site, including viewing from upstairs windows (how many of us do that?)
Be aware, JKW is a great problem for our industry, and is not something we can ignore. Neither can we plead ignorance of its’ presence when conducting site surveys.
We cannot abdicate our responsibilities as professionals when conducting surveys. This is a fact, irrespective of whether or not we are being paid to conduct such inspections. Money does not have be involved, as you will be deemed liable as you will be held to have a financial interest in the survey, even if it is only speculative (in the case of Contractors, assessing a site).
For more information, and to view many similar features and articles, please see www.landscapelibrary.co.uk
All articles are written by Professional Consultants, mainly Members of The Professional Garden Consultants Association (PGCA) www.pgca.co.uk