Magazine - Japanese knotweed - stem injection the answer ...

By Editor in Consultancy on 22nd Dec 2008 9:00

Weather-wise this summer was a washout but it has actually helped the new stem injection treatment method for Japanese Knotweed come into its own.

Rumours of a new stem injection method led a UK based company, traditionally offering chemical folia spraying and 'dig and dump' treatment methods, to investigate further. Its online research led it to an American entrepreneur, Phil Burgess, who had spent several years perfecting a new stem injection technique in the United States.

Whilst there was nothing especially new about trying to inject a herbicide directly into a plant, and its effectiveness had indeed been common knowledge amongst gardeners and horticulturists for a century or more, the one thing that had hindered its development was the ability to design an injection system capable of achieving consistent and accurate herbicide delivery.

The American's own R&D work had seen him experiment with plant injections using various hypodermic needle sizes, finally arriving at a prototype applicator - the JK Injection Tool - which was able to accurately deliver a dose of herbicide into a plant stem.

The stem injection system works by delivering a measured dose of concentrate herbicide into the centre of the plant rather than just to the surface. This means the treatment is extremely localised, only ever targeting the plants injected and preventing the environmental risk of drift spray, run off or contamination of watercourses and other sensitive vegetation. The weed will also absorb the concentrate into its rhizome (root) at a much faster rate than with folia spraying, providing a quicker resolution to the Japanese Knotweed problem.

Other traditional methods all have some practical flaws. Chemical spraying can harm other plants and wildlife in the area, is expensive and by no means 100% effective. Digging out the weed is even more expensive, must be repeated a number of times to remove any trace of roots or rhizonic growth and must be disposed of as hazardous waste, filling valuable landfill sites with huge quantities of contaminated soil.

So, the precise control, the speed and the practicality of an injection delivered herbicide appears to be the obvious solution. The fact that it can be applied in all weathers throughout the growing season of April to October has also been a major advantage - a silver lining to this summer's plentiful clouds, enabling treatment to carry on undeterred by the constant downpours.

The new system can treat plant clumps in minutes meaning treatment times for knotweed removal are reduced by up to five times over conventional spraying.

One of the first local authorities to use the new method was Stockport Council, its parks and recreation team buying a pair of the new injection tools last year and using them virtually non-stop for the past two summers across its parks and public areas.

Henry Campbell-Ricketts, a senior officer within the council, said "The way the stem injection method has solved the problem has been better than we could ever have imagined. We are confident we have found a solution that can get rid of Japanese Knotweed with just one treatment and we will continue to use this method in areas that are time critical and ecologically sensitive."

Another public sector client, Ipswich Borough Council, began researching alternatives to its existing practice of 'cutting and burning' weeds. It now employs a dedicated two man stem injection team working throughout the year to treat the borough's problem.

Nick Wilcox, area manager of the council's Grounds Maintenance Department said "We have over thirty different infestations on council land across the borough ranging from ten square metres to over two hundred square metres in size.

There was initially some scepticism about the stem injection treatment from our external amenity consultants but we have been nothing but highly impressed with the results since our early trials began.

Treatment call-back times and ongoing labour costs have been dramatically reduced and I can't speak highly enough about the method's effectiveness and the support we've had. We now have an additional problem with another weed species, Giant Hogweed and we have gone back to the UK distributor, Japanese Knotweed Control, to discuss suitable treatments."

Joint managing director of the company, David Layland, said; "Using the stem injection system ourselves we know just how effective it can be, but it's reassuring to hear from customers who have bought the equipment through our sister company and seen the benefits first hand. It supports our belief that stem injection is the way forward for Japanese Knotweed control."

Read more articles in Consultancy, by Editor or from December 2008.