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Message Board - Pests, Weeds and Diseases: Knot weed

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Pfidge
Posted 2 Jan 2006
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I want to spray some knot weed and wondered if anyone can recommend a good chemical that isn't too expensive that will deal with this and an address or phone number in the Kent area of a supplier. Thanks. Phil
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Charles Johnson
Posted 3 Jan 2006
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Too late to be spraying Japanese knotweed, it naturally dies back and goes dormant in Autumn and spends time sharpening its spears for Spring.

Glyphosphate (RoundUp) is the recommended treatment, applied when the knotweed is actively growing (the very best time is just after flowering, pick a warm day in Summer). You may need to repeat spray, don't expect to win the fight against a mature thicket in the first year.

If like me you get impatient and cut the stems down, you can also syringe the stumps with extra concentrated RoundUp.

Dead top growth is not the problem, it can be shredded or burnt. The hazard of this weed comes from the enormous and brittle root systems, every little piece of which is capable of forming crowns and throwing up new spears. If you start digging, it all needs to be handled as contaminated waste.

Good luck
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ticky21
Posted 4 Jan 2006
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Ticky supports British farmers...!!

hi Pfidge an Charles Johnson, not knowing the location of offending plant, ie garden/golf course/estate, while its dormant, could it not be dug/scraped up with a mini-digger and area re-landscaped, (just a thought)....Ticky
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Groundsmaiden
Posted 4 Jan 2006
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Posts: 352

A word of warning on your comment Ticky, any waste material created by cutting, mowing or excavating Japanese Knotweed has to be disposed of according to the Environmental Protection Act (1990)(Duty of Care).

A tiny fragment of root (as small as 0.8 grams) transported by people or water can grow to form a new plant.

If you're going to control is chemically, it takes a minimum of three years to totally eradicate it. During this time it must be regarded as infective.
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PNCawood
Posted 4 Jan 2006
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A weed is a plant whose virtue is yet to be dicovered.

DCP_0428.JPG
Dear PFidge and Ticky,

Groundsmaiden Ellie is exactly right. BEFORE you plan any treatment of the Japanses Knotweed, be aware of the TWO acts of parliment that apply to 1. Causing it to spread through proporgation and 2. movement of waste (ie soil) that contains its rhizomes. 1. The wildlife and countryside act 1981 and 2. The environmental protection act 1990. You cant simply hack it down and treat it, or scrape it out and smooth it over. This tends to annoy it and causes it to spread like wildfire.

Depending on proximity of water courses and other desirable vegetation your treatment options are limited. A GOOD specialist contractor could help you with this - I can let you have some no's if you like.
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Cranfield
Posted 4 Jan 2006
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Posts: 243

Please see the article on the Pitchcare site about Japanese Knotweed. It also provides links to Defra and other sites that promote information about controlling Japanese Knotweed.

www.pitchcare.com/magazine/article.php?id=1580

Regards Laurence Gale
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ticky21
Posted 4 Jan 2006
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Posts: 1808

Ticky supports British farmers...!!

jesus, i never knew this stuff was such a pain in the rear..... almost as bad as ragwort in grazing land,.. off the top of someones head, how did we come to have this stuff get so rife.. the knotweed i mean...
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Groundsmaiden
Posted 4 Jan 2006
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Posts: 352

Not sure how it got here but I understand it originates from the upland volcanic slopes and woodland edges in Japan.

I presume it has spread in the UK due to irresponsible planting and lack of control in the early years.

Because the nutrient statues of the soil isn't important it can take advantage of opportunities to establish pretty much anywhere in the UK and unfortunately many people are not aware of the problems it can cause if left untreated or if its dealt with incorrectly.
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PNCawood
Posted 4 Jan 2006
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Posts: 100

A weed is a plant whose virtue is yet to be dicovered.

Hi Tricky

It was brought over by the victorians from japan. It was highly prised as an ornamental in well to do gardens. Since the 1900's it has been spread by illegal dumping by fly by night operators, by mechanical means by local authorities such as mowing and contaminated equipment. It doesnt seed but 1cm of rhizome will easily spawn a new stand. This weed makes ragwort look like a daisy. It's easily the worst weed in the world to treat.
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Pfidge
Posted 4 Jan 2006
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Firstly thanks for all the replies, but it appears that there are two kinds of knotweed and I think you are talking about a different kind.
I meant KnotGrass (knot weed).
This is an annual weed and has taken hold on the rugby pitch. Which selective weed killer could I use.
Thanks very much but this was all very interesting and I hope I never get any of this. I thought I had problems!!!!
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Groundsmaiden
Posted 4 Jan 2006
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Posts: 352

In good Simpsons style.................Doh! Oh well, we got a good bit of information out of the conversation anyway lol
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Hipper
Posted 5 Jan 2006
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Knotgrass - Bastion T has been very effective when I've used it. Now is not a good time though. Wait until it is actively growing again.

Knotweed, Japanese - bearing in mind all of the above, my best success where it is growing in hedges or shrub beds was to dig it out as best as possible, then treat the inevitable new growth with gyphosate as often as nescessary until it is eradicated, which may take a couple of years.

If Japanese knotweed is growing out of pavements stones etc, use glyphosate if practical, then cut down when dead. When it reappears, either strim or use glyposate until it it finally gives up.
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Peter Leroy
Posted 5 Jan 2006
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Hence the use of botanical names, that way all, no matter the local language, understand.
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ticky21
Posted 6 Jan 2006
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Posts: 1808

Ticky supports British farmers...!!

maybe some of our readers arent up on botanical/latin names, i myself cant remember all the genus-species-cultivar ident speak that i was s`posed to remember from college, a lot of readers just know it as that pain in the a**se, tall s**t that wont bloody well die, not even with the aid of a napalm bomb....mind you what are the rules on bar b qing the damn stuff, is burning a big no no as well cos of air borne spreading etc ???
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Peter Leroy
Posted 6 Jan 2006
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Ian
Posted 13 Jan 2006
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While still sort of on the subject of Knot weed the (Japanese variety) I have heard of total erradication by strimming the stems to expose the cambium layer, then spraying with Garlon 2.
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PNCawood
Posted 13 Jan 2006
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A weed is a plant whose virtue is yet to be dicovered.

You are wasting your time strimming and then spraying - you will deliver more herbicide (triclopyr in Garlon / timbrel) by applying to the foliage so it can be moved to the part you want to kill - the Rhizomes through the nutrient movement of the plant anyway. Strimming will just annoy it and cause the secondary nodes to trigger and make it spread. A thorough application of triclopyr will knock out 95% in the first year BUT YOU MUST go back to finish it the following year.
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