Japanese Knotweed, starting to get fed up, glycosulphate time

[pat32rf]

We do have other patches of it in other areas. It will grow anywhere there is enough light. Along the driveway it makes a nice summer edging that I can snowplow down when the snow gets deep.
In most areas I just use the weedeater a few times each year, but there are three isolated areas where I want to eradicate it to plant A-lawn, B-flower bed and C- Raised bed for grape plant and tomatoes. Logic tells me that if I chop off a plant whenever it sprouts a leaf, and do this weekly for 2-3 years, its GOTTA die. I have all the root clumps out of the three area, been using premix Roundup (7% last year, 14% this year)
Chickens, woodchucks nor deer will eat it.

 

[whirly]

I had Canadian Thistle which has a horrendous root system. I had to wait until it set the first flowers and before they opened fully to spray and then sprayed lightly every day for a week. Let it just sit for another couple of weeks and never saw another shoot. As stated before if you kill off the foliage before it has a chance to get into the root system you are left with live roots that will propagate in the spring again.

 

[Ranger Rick]

Logic tells me that if I chop off a plant whenever it sprouts a leaf, and do this weekly for 2-3 years, its GOTTA die. I have all the root clumps out of the three area, been using premix Roundup (7% last year, 14% this year)

We have some that I have been mowing every 2 weeks for 3 years and it has not gone away. I did not know what it was until you posted and I looked it up. When it comes to invasive plants they all defy logic. Guess we should get out some Roundup and get rid of it.

 

[pat32rf]

Been spraying it with Roundup on Fridays and Mondays now for three weeks. Shoots are about 6-8" high and look healthy. This is after cutting down the plants to ground level every few days for the past 3-4 years. Going to add 2,4D as well.

 

[Express]

Have any of you had success in irradiating the Knoweed this year?

 

[dave1949]

I have a small patch I need to deal with. I just read a recommendation in a gardening article to mow it in June (in Maine) and then spray it with roundup in August. There was no rationale supplied for this plan, so who knows.

 

[Express]

That's great you have a small patch. I had a huge one. Take my advice. Carefully dig out what you can and burn it. Lay plastic down because it will speed easily. If the plants are large cut stems and pour concentrated Roundup down stems. Then cover area wealth a heavy Geotextile landscape fabric extending areas by 2 feet on all sides and cover with gravel to keep it weighted down. I want to strongly point out the stuff spreads like crazy. It was growing in the wheelborrow after I removed it. This stuff was going to grow into my septic area and that would have been a nightmare.

 

[dave1949]

That's great you have a small patch. I had a huge one. Take my advice. Carefully dig out what you can and burn it. Lay plastic down because it will speed easily. If the plants are large cut stems and pour concentrated Roundup down stems. Then cover area wealth a heavy Geotextile landscape fabric extending areas by 2 feet on all sides and cover with gravel to keep it weighted down. I want to strongly point out the stuff spreads like crazy. It was growing in the wheelborrow after I removed it. This stuff was going to grow into my septic area and that would have been a nightmare.

A lot of that isn't an option in my patch. It is growing around an old cellar hole with rocks here and there, and a thick stand of black locust trees. On the other side of cellar hole area among more rocks and trees is a patch of garlic mustard, another invasive.

Most of it I can't mow or get any ground engaging equipment on it. I'll get what I can with the brush trimmer blade on my string trimmer and spray it for starters. I can contain the area but not really get into it very effectively.

The garlic mustard seems more inclined to spread than the knotweed. Black locust isn't native here either, just to round things out. :laughing:

 

[forgeblast]

I hit it a few times last year. Its down to nothing this year. I figure one more year and I will hopefully have it gone.

 

[geko]

In the UK there's very tight regulations on Japanese knotweed - it's becoming a major problem. If you're building on a site, for example, and find it, you've got to excavate it all to a depth of, I believe, at least 3 metres, get the soil removed by covered wagons, which also have to be sprayed, the soil incinerated, then buried!!
It's as bad as asbestos to remove legally and safely over here.

It's said that a piece of the plant as big as your thumb nail can grow & takeover again, hence the strict regulations!