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Giant Hogweed recognition

Mike Thompson

Mike Thompson

Senior Member & Supporter
Hi all,
Been reading about the skin problems associated with the sap of giant hogweed. Looked at pictures on the net and basically it is like cow parsley but grows much taller and with thicker stems.
My question is, how do you recognize it if it is not full grown, surely it then looks just like harmless cow parsley.
Any advice gratefully received.
Mike
 
Mike Thompson said:
Hi all,
Been reading about the skin problems associated with the sap of giant hogweed. Looked at pictures on the net and basically it is like cow parsley but grows much taller and with thicker stems.
My question is, how do you recognize it if it is not full grown, surely it then looks just like harmless cow parsley.
Any advice gratefully received.
Mike
Click to expand...

The edges of the GH leaves are massively more serrated - just study comparative pics on the web - and are very different in size and movement when it first emerges out of the ground. Just huge leaves, especially when it's already been cut (say by a strimmer). When it grows back up (often within a couple of weeks of being mowed/strimmed) it first spreads its leaves out across the ground with a huge diameter, to block out rivals before it goes upwards, faster than anything except bamboo and balsam.

I will not give any advice on tackling it.
 
It is often mistaken for other members of the carrot family when its at the early rosette like stage, the smaller (native) common hogweed being one. The leaves are much more deeply incised than cow parsley, and usually smoother, shinier and more serrated around the edge than common hogweed. Once it gets a bit taller, giant hogweed is noticeably more hairy around the leaf joints of the stem - it's unmistakable.

Take an identification guide/key down to the bank with you and you'll very quickly get your eye in Mike, but until you do, just make sure you wear gloves!
 
Thank you Graham and Dave, I feel more confident of recognising it now.
Going to the Nidd soon and its banks are a real jungle, so want to know what I am trampling on.
 
Thanks Joe, it's the leaves that look like the best identification point, till fully grown.
Hopefully this will help others too.
Mike
 
Yes Gavin,
I was pretty sure I had seen some on recent walks down the Derwent and the Nidd, that's why I asked, to make sure I know what to avoid.
Thanks again,
Mike
 
I recently and successfully applied for a spraying licence from NRW to tackle a severe giant hogweed problem on a club stretch of the Severn near Welshpool (it was so bad, we had to close the length to fishing last year). Recently we spent three full days, spraying it, with glyphosate and along large sections of bank, it was the only plant growing (out competing everything else). A bigger problem is that the growth extends well beyond our boundaries and being on the Upper Severn (and it grows all the way upstream to Newtown), it couldn’t be in a worst place, as if left unchecked it will spread downstream and all along the Severn.

Both the Welsh EA and English EA do nothing to tackle the problem; blame austerity or say the problem lies with the landowner. The Severn Rivers Trust occasionally apply for grant money when it becomes available and then employee expensive contractors to spray a small length of river, with no real coordinated approach.

This plant is the biggest threat to the Severn (and other rivers) and putting the human health risks aside, when it dies and rots down, the root void is the size of a football and as a result, winter floods can wash large sections of bank away and silt up valuable gravel beds.

It’s all a bit depressing! :mad:
 
http://www.nonnativespecies.org/downloadDocument.cfm?id=997

Yes it is dispiriting when you read what we are up against Neil.
Up to 50,000 seeds per plant that can stay in the ground for up to 7 years and germinate, ...some after 15 !

A club can spend a lot of time and effort keeping it at bay only to recieve further infestations from upstream. Awareness and recognition is a step forward which may lead to a concerted effort by those with a vested interest perhaps?

ATB Dave
 
I've found cattle grazing and trampling can really help to stop giant hogweed getting established in the first place. Cattle grazing is also one of the best ways to deal with Himalayan balsam - because of the high water and sugar content they love the stuff.

Unfortunately I'm seeing lots of examples of watercourses being fenced off - often because the farmer has been advised to in order to prevent cattle causing bankside soil erosion. So the cattle get fenced-out, and then low and behold five years later the banks become infested with Himalayan balsam (or worse), which rots down come November leaving very little bankside cover, thus actually encouraging or rather accelerating erosion!

Anyone involved with a club/syndicate/landowner that is looking at fencing of sections of river bank, would be well advised to ensure that the fence, if deemed necessary, is placed well bank from the top of the bank (say 10-15m), with plenty of gates put in to allow livestock access easy access to graze the bankside vegetation for a few months of the year. They can often get grants to compensate for the reduction in grazing area.
 
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