Japanese Knotweed, starting to get fed up, glycosulphate time

[pat32rf]

About five years ago I dug out a few patches of this stuff with the backhoe. Then I would take the shovel and cut off any shoots as soon as they formed leaves for the next three years. Last year I tried regular Round-UP which is 7% (?) I would spray any leaves, let sit for a few days, then dig with a shovel. This year I let the shoots get about 8" tall, then dug out what I could with the backhoe (again) and followed this with alternating doses of 2,4,D and stronger (14%) Roundup. Each time I sprayed I would leave the plants for a couple of days, then try to dig out any roots but a lot of the main roots are 24" down.....
Its been suggested that I obtain some American Roundup as we are not allowed to use anything potent for cosmetic weed control here in Ontario and 14% is as strong as I can buy. Is American stuff any stronger? (I know, its not really 14%, but 14 grams, per liter or something)

 

[murphy1244]

see if you can buy pathfinder

 

[LD1]

We can get concentrated round-up here. 42% isnt uncommon. Suggested mixing is like 2-3 ounces per gallon.

But stronger may not be the answer. You want a slower kill to get the roots. Too strong and it is less effective. Only waiting a few days may be your problem. Try waiting a few weeks. Thats about how long round-up takes to kill the roots even though it will brown in a few days. But give it time, it is still working.

Also, maybe roundup isnt effective on that plant??? We have other stuff here that is FAR more potent than roundup. Stuff like pramitol 25e that will even kill large mature trees if sprayed too close. You may also want to try brush killer products also.

 

[forgeblast]

http://dnr.wi.gov/topic/Invasives/documents/japanese_knotweed_control.pdf
I have been dealing with it for a long time. And once I have it under control road work is done which moves new rhizomes into the area. its a frustrating plant.

 

[Storm56]

I too have this invasive plant on my property. My problem is that I have almost 1 mile of a stream that goes through my property and above me the owners do not even know what it is, much less control it. So the seeds get into the stream and every year we when we have high water I get re-infested. So I have just conceeded that I will always have an ongoing control problem.

I use 3 different sprays. Glycophosphate, 2-4D and Crossbow. Usually mix 2 together. If you catch them when they are young, as not yet spread into clumps, they kill very easy, if it has expanded into a clump, you have to watch it and re-spray when it starts to grow again, and it will. So about 3 times a year I go for a walk with my backpack sprayer and hunt for it. I have gotten very good at picking it out when it is young.

 

[hosspuller]

About five years ago I dug out a few patches of this stuff with the backhoe. Then I would take the shovel and cut off any shoots as soon as they formed leaves for the next three years. Last year I tried regular Round-UP which is 7% (?) I would spray any leaves, let sit for a few days, then dig with a shovel. This year I let the shoots get about 8" tall, then dug out what I could with the backhoe (again) and followed this with alternating doses of 2,4,D and stronger (14%) Roundup. Each time I sprayed I would leave the plants for a couple of days, then try to dig out any roots but a lot of the main roots are 24" down.....
Its been suggested that I obtain some American Roundup as we are not allowed to use anything potent for cosmetic weed control here in Ontario and 14% is as strong as I can buy. Is American stuff any stronger? (I know, its not really 14%, but 14 grams, per liter or something)

For one thing ... Stop digging it out. Spray the glysophate on it and let it work. The glysophate works by making the plant GROW uncontrolled. Sort of like plant cancer. That's why "round-up" doesn't work in a drought, the plant/weed isn't growing.

Another thought. are you using a ready to use or are you mixing a concentrate? Hard water in a mix will reduce glysophate effectiveness. Adding ammonium sulphate will help.

 

[RobertBrown]

Anytime you have an invasive plant that reproduces using rhizomes...you've got your hands full. Apparently this is a tough one to eradicate. So the sooner you start, and the more drastic the measures, the better your chances of success are. Don't rule out turning over 2' of dirt to get rid of this plant as if you don't get it under control it will take over.
Before you do anything, take a look around at your neighboring properties and see if there isn't a very established population of these plants. If that's the case then you will need to start there or re-infestation is inevitable. As I said, this plant reproduces under ground with it's roots, so determining how it got to your property will be key in it's permanent removal. One would think that you have this plant nearby in order for it to have appeared at your place.
If your using herbicides.....now is the time to start finding the right and most effective one.

The most effective method of control is by herbicide application close to the flowering stage in late summer or autumn. In some cases it is possible to eradicate Japanese knotweed in one growing season using only herbicides. Trials in the Queen Charlotte Islands (Haida Gwaii) of British Columbia using sea water sprayed on the foliage have demonstrated promising results, which may prove to be a viable option for eradication where concerns over herbicide application are too great.[citation needed]

The bright side here is this plant is edible and used as a vegetable in Japan. So that means if you could eat it so could some type of livestock. If it does get away from you, you could turn it into "leg of lamb" or goats milk or jerked goat stew :licking:
According to this Glyphosate is effective
Japanese knotweed - Wikipedia, the free encyclopedia

 

[forgeblast]

Just spray it closer to night so your not spraying the bees if it does go to bloom. Also the seeds will not grow new plants. I always wondered if planting black walnut near it would have any effect.

 

[Storm56]

Any idea's on how we can inform our local deer population that this plant is edible??!!! They will not touch it!

I actually had a fair bit of this before I realized how invasive it is. I enjoyed when it flowered as it is a good looking plant. When I found out what it was and that it was in my best interest to eradicate it before it really got out of hand, I already had several large clumps started. Some of them took me 4 years to get rid of. I just kept after them and when I saw growth I would hit them again. On one occasion there was no growth for a full year then the following year they again started growing. Nasty stuff! As I previously stated, easiest to kill when it is young.

 

[Storm56]

Any idea's on how we can inform our local deer population that this plant is edible??!!! They will not touch it!

I actually had a fair bit of this before I realized how invasive it is. I enjoyed when it flowered as it is a good looking plant. When I found out what it was and that it was in my best interest to eradicate it before it really got out of hand, I already had several large clumps started. Some of them took me 4 years to get rid of. I just kept after them and when I saw growth I would hit them again. On one occasion there was no growth for a full year then the following year they again started growing. Nasty stuff! As I previously stated, easiest to kill when it is young.