THE LAST WORD
MAX WADE
Looking out for Giant Hogweed
and avoiding its effects
By Professor Max Wade, chairman of the Property Care Association’s ‘Invasive Weed Control Group
arlier this summer we issued a warning to
those in the landscaping and associated
industries, urging caution with the
invasive weed Giant Hogweed. The plant’s sap is
extremely toxic to human skin in sunlight, making
it a danger to public health.
The PCA wanted to let people know that if
anyone comes into contact with any part of the
plant, followed by exposure to sunlight, they
can sustain severe blistering to the skin and
discomfort, which can become a long-term
condition, recurring in subsequent summers.
Once again, Giant Hogweed is turning out to be
a summertime problem. It is continuing to spread
and, in just one area alone, the chairman of our
Invasive Weed Control Group, Professor Max
Wade, reported seeing it appear in five
new locations.
It is really important that the plant is spotted
and that its toxic sap does not come into contact
with skin in the sunlight. If this occurs, it can lead
to a nasty rash, itching and blisters when skin first
makes contact with it in sunlight. Worryingly, the
rash and the itching can reoccur and flare up for
years afterwards when skin is exposed to sunlight.
An added concern is the fact that an individual
can come into contact with Giant Hogweed sap in
cloudy conditions but later on the sun comes out,
the photochemical reaction occurs and they are
affected by blistering and a rash.
Likewise, sap which comes into contact with
items such as clothing and equipment, can also
be transferred via touch - so it can possibly affect
somebody else if their skin is also exposed to
sunlight. For example, were a flail mower used to
cut through vegetation including Giant Hogweed,
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be cleaned after completing the work and the
operative then goes out into the sunlight with sap
on their skin, they too would be affected. It is this
delay factor which makes detecting the source of
the blistering and rash a difficult one.
We’ve been made aware of a number of reports
of people sustaining injuries after coming
into contact with the invasive weed in the UK
in recent years. The chemical in the plant, a
furanocoumarin, needs bright light to react
with the skin and causes blistering and other
health problems, so this is the time of year when
problems can ensue.
If you make skin contact with this plant or
think you might have, cover the affected area from
sunlight and as quickly as possible thoroughly
wash any sap away, preferably with warm and
soapy water. Visually, the plant’s stature sets
it apart from the UK’s native hogweed. Giant
Hogweed can grow up to 3 metres high with a
2 centimetre diameter stem and a large, white,
umbrella shaped flowering head.
The general public, as well as local authorities,
statutory agencies and landowners on whose
property people can come into contact with
the plant should be aware of the risks and
Giant Hogweed needs to be controlled and
managed professionally. Obviously, those in the
landscaping industry also need to be well aware
of the issue too and work to prevent the spread of
this plant, a tall order given the thousands of seeds
produced by a single plant.
More details on the conference can be found at
www.property-care.org