12.8.95

Battle joined against the 
evil Russian giants 

Britain's rivers and the public's health face a sinister threat, reports John Sheard

THE cold war may be over but this hot summer a fierce battle is under way on Britain's 
riverbanks against a stubborn Russian invader which can kill native plants and inflict severe 
injuries on human beings.

The water-loving giant hogweed (scientific name: Heracleum mantegazzianum) may not 
be quite as deadly as the plants in John Wyndham's science-fiction classic, The Day of the 
Triffids, but as one worried salmon angler in Cumbria said dolefully: "It's the next worst thing."

Its sap contains chemicals called foucoumarins which can cause severe rashes and blisters, 
painful enough in themselves. But they have another, more sinister, side effect - they 
drastically reduce the skin's resistance to sunburn. People, particularly children, who have 
been burned and continue to work or play in strong sunlight can suffer serious long-term 
effects. The spread of the plant has caused the National Rivers Authority to issue urgent 
warnings to parents and detailed advice to riparian owners on how to tackle the invader.

One senior NRA ecologist, Ed Mycock, who has made a long study of the plant, said: 
"This is a very unpleasant and even dangerous species with an enormous seed production. 
Unfortunately, it is now taking over large areas of riverbank throughout England and Wales 
and into the Borders.

"It can represent a very serious health risk, particularly to children who - mistaking it for 
one of the many species of cow-parsley which are native to Britain - try to make telescopes 
or peashooters out of its hollow stems.

"Some can end up in hospital and be scarred for life. Even for adults it can represent a real 
threat, particularly on hot sunny days, for it causes a serious reduction in the skin's ability to 
absorb sunburn.

"There are ways to deal with it but we recommend that no one, however skilled and well 
protected, tackles full-grown examples, which can stand five metres high."

The giant hogweed comes from the Caucasus mountains in the former Soviet Union and, 
like so many now-native pests, it was imported deliberately to decorate 19th-century country 
gardens. With a reproductive rate of some 50,000 seeds per year, it did not take long to break 
free from its ornamental beds - the seeds can be distributed either by wind or water - and it 
slowly began to colonise riverbanks throughout the country, starting in the South-East and East Anglia.

It has been marching north and west ever since and is now colonising the banks of salmon 
rivers in Cumbria such as the Eden and the Lune, and the Tweed in the Borders. So alarmed 
are NRA officials that they have issued a special booklet for schools, local health authorities 
and riparian rights owners, asking them to report any sightings of the plant to local NRA offices.

The giant hogweed can be destroyed, either by the labour-intensive digging out of new plants 
or by the use of Roundup, a glyphosate-based systematic herbicide which is approved for use 
near - but not in - water. But the booklet advises care and caution.

Ed Mycock said: "We are very eager for the public to report sightings of giant hogweed so that 
we can help set up eradication programmes. No one should try to destroy a fully grown plant - 
that is too hazardous even for experts. The location of such plants should be noted so they can 
be destroyed as they grow again next spring."

'Guidance for the Control of Invasive Plants Near Watercourses', offering specialist advice to 
riparian rights owners, is available from NRA offices.