GIANT HOGWEED CONTROL PROGRAM ENTERS ITS SEVENTH YEAR

The Giant Hogweed control program in the Medway Valley has entered its seventh year. With the co-operation of more than 70 landowners, the Medway Valley Countryside Partnership has been able to substantially reduce the numbers of this highly invasive alien plant. 

Giant Hogweed is both a public health hazard and detrimental to our native wildlife. Its sap can cause serious skin inflammation when exposed to the sun.  Mature Giant Hogweed plants shade out our native species, and leave the ground vulnerable to erosion come the autumn. It can be differentiated from related native species such as Hogweed, by its early bright green growth in spring, being one of the first plants to appear,  the jagged spiky ends to the leaves and the dark red blotches on the hairy stems of more mature plants. Later on in the summer it can grow extremely large (up to 5m) with huge cauliflower like flowers.

With the help of our sponsors, Kent County Council, The Environment Agency, Tonbridge & Malling Borough Council, Maidstone Borough Council, and landowners, MVCP will continue to tackle this problem throughout River Medway catchment area. If you are a landowner and would like information about next year’s scheme, or if you know of the location of Giant Hogweed plants, please phone us on 01622 683695 or e-mail Anna Presswell

Japanese Knotweed

Japanese Knotweed (scientific name Fallopia Japonica) was introduced to the UK in the mid-nineteenth century as an ornamental plant. It first became naturalised in South Wales.  Japanese Knotweed has now infested large parts of the country, through a combination of vegetative means, and by human activities, such as fly tipping garden waste and moving contaminated soil. Mechanical flails and mowers will also spread the plant. It is a damaging and invasive plant, which can shade out and out-compete native species causing a concomitant loss of bio-diversity.

Stand of Japanese Knotweed

The Wildlife and Countryside Act 1981 makes it an offence to plant or cause Japanese Knotweed to grow in the wild. Any excavated soil from areas were Japanese Knotweed has established must be disposed of at a licensed landfill site and not reused in further construction or landscaping. There are currently no biological controls for this plant in the UK. A series of natural pathogens are under trial, but it is unlikely that this research will come to fruition for several years yet.  

Japanese Knotweed is an opportunist and will readily establish itself in any disturbed site. It may commonly be found in the following types of location:

 Linear corridors

·         Railway embankments

·         Adjacent to footpaths and roadside verges

·         Along rivers and streams 

On established sites of human activity

·         Derelict land

·         Former quarries and landfill sites

·         Private gardens

·         Industrial sites

Control of Japanese Knotweed relies on the death of the extensive rhizome system, which usually takes a number of years. This can be achieved in one of two ways.

Cutting or Pulling

Regular cutting or pulling will, after a number of years, eventually exhaust the rhizome and kill the plant. It is important that all cut or pulled stems of Japanese Knotweed are kept on site, or disposed of at an approved landfill site. Stems, crowns and rhizomes readily regenerate, they must be allowed to dry out thoroughly after they have been pulled or cut.

Herbicide Control

Dense stands of Japanese Knotweed can be treated with a glyphosate based herbicide, such as 'Roundup'. It may take two or three years to completely kill the entire plant. More effective control can be achieved if Japanese Knotweed is cut or sprayed in early summer, then again in late summer, just before the winter dieback.