Is Japanese Knotweed Poisonous?

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w1bbler

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A bridlepath I hack along is covered in the stuff & my horse is constantly trying to eat it (well the leaves are at head height). He only manages to catch the odd leaf, but do I need to worry.
Checking the web, companies that make money out of removing it say its poisonous, but other articles say not. Anyone definately know the answer?
 
No it isn't poisonous, in fact the Japanese use it for a vegetable I understand. However it is an offence I think to allow it to thrive (something to do with it being non native species) I had it in my field and killed it off. It isn't that easy to kill unless you get radical with it. I used very strong roundup on it in August. I kept giving it a spray until it started to look sick and then gave it another blast for good measure. Probably not best practice but I got rid of the flippin thing. If you have it on land that you want to develop then you won't get PP on that land until it is eradicated. It is awful stuff and comes up through concrete!!!!

I wouldn't worry too much about your horse on a hack though.
 
Not poisonous but it can cause some damage to structures such as houses, walls etc. noticed some near us recently- told the farmer and he says he will deal with it but nothing so far. It is quite difficult to get rid of because of the strength of the roots.
 
No it isn't, and it is delicious too, I've eaten in cooked it like rhubarb.

However, as people have said you MUST report it, and if it's on your land go after it with herbicide until it's dead. The standard method is to either spray once a month from March to October, or to wait until the shoots are hollow (May ish) and then cut them (boil the cut stalks to destroy them) and pour herbicide into the stem cavity. Glysophate (marketed as round up) is effective if you use it in a sustained manner. If you leave it, not only are you breaking the law but it will spread and spread and spread. If you end up having to dig it out you have to take 5m all around and 3m below the rhizomes (roots) which is a HUGE volume, and it usually has to ALL be disposed of as hazardous waste - that's potential 10's of thousands of pounds...

And yes, I am a consultant ecologist!
 
Sorry if Im a bit thick here, is this the sticky leafy stuff growing in abundance at the moment? If so my horse loves it..
 
hubby works for the EA and it is a notifiable weed as it isn't native to the UK but although you can eat it when cooked it is not advisable to try to handle it raw as the hairs on the plant can blister the skin. I wouldn't let a horse eat it as you don't know what damage it is doing internally.
 
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