Park manager for Kensington Gardens and Brompton Cemetery in London Andy Williams has called in the company to advise on knotweed issues at both sites, after working with the contractor on and off for six years.
He said: "I have always been very impressed with Japanese Knotweed Control (JKC)'s approach to managing our parks' knotweed issues, as well as its willingness to work with ground staff to educate, increase overall awareness and develop understanding of the problem.
"We currently have a couple of knotweed stands alongside the Long Water in Kensington Gardens and it's reassuring to be able to consult a specialist that, based on experience, we can trust to achieve results."
JKC was first engaged by Royal Parks in 2008 to undertake a Japanese knotweed treatment programme at The Queen's Orchard in Greenwich Park.
The management team at Regent's Park called on the company again in 2010 to tackle 19 infestation sites, most of them located in the 416 acre Regent's Park as well as treatment of one large isolated knotweed stand in Primrose Hill.
Williams, who was assistant park manager there at the time, decided that stem injection treatment was the best way to tackle the problem. He said he was pleased with the bespoke treatment plan offered.
"The stem injection system was extremely successful in eradicating the problem at Regent's Park, moreover it fulfilled all important environmental criteria by eliminating the potential risks to our plant and gardens posed by traditional foliar spray applications."
JKC also returned to Regent's Park in 2011 to train 45 gardeners about knotweed and also to tackle outbreaks at London Zoo and the Open Air Theatre as it underwent some redevelopment work.