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Discussion Starter #1
Well I've spent the spring and summer torturing my Knotweed patch. It turns out to be just about an acre in size and I have mowed and sprayed and mowed and sprayed the Knotweed over and over. I lost the exact count, but I know I've sprayed it at least 4 times this season. I'm afraid that I may be developing a Round-up ready strain of the stuff. I have been using 2 quarts of Power Max per 25 gallons of water, and it's not even putting a dent in the Knotweed. I've got to eradicate this stuff and reclaim this area. Any suggestions would be greatly appreciated.
 

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Anytime roundup has not worked for me, the problem seems to never go away. I am interested to see what some of the more experienced guys have done!
 

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Maybe you are spraying it when it is too small. It needs to absorb enough of the glyphosate to kill the roots. If the exposed surface is small only a minimal amount is absorbed. Same thing with multiflora, if you cut it and wait for new re-sprout to spray it won't take enough poison to kill the root. Better to wait until it is a couple feet high and then saturate.
 

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The army corps has been trying various techniques and sprays up here along the Tioga River by the Lambs creek boat launch. Their main office is located in Ives Run Park. You may want to contact them and see what they are using.
 

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Hard work does pay off, but with Knotweed you need to treat it at the right time of year to make a dent in it. It is a VERY aggressive invasive plant.

You need to affect the root system. That is where all the energy is stored.
Let it spend a bunch of energy growing in the spring. If you can, mow it down around July 1st. Let it spend more energy sending up new growth and then hit it with glyphosate (Round Up). If you can use a surfactant with the herbicide as that will allow the herbicide to stick to and penetrate the leaves. If you are unable to use a surfactant, trying using some Dawn dish soap. It will help penetrate the waxy leaves and also help it stick.
The object is to get the root system to spend as much energy as you can. The plant cannot continue to survive if you keep treating it that way.
Good luck!
 

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It may not be availible to you, since I used it as a commercial applicator(had my commercial license) at my former job, but we killed a ton of it using a 7% accord(glyphosate) 2% Escort XP, and 1% Habitat, and 1% Clean Cut(surfactant) mixed with water and applied to the foilage via backpack sprayers. It completely killed it in about one week, and it hasn't returned in the areas we sprayed it. We applied the spray in later june/early july and some of the plants were over 12 feet tall. Also, mowing it can promote vigorous new growth, and the mowed, cut up pieces have the ability to sprout roots and contribute new growth also. Not mowing, and spraying may be your best course of action.
 

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If you really want to kill it use spike. it will kill everything though. you could try something like trizmet or banvel.
 

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CJ,

I scanned a Penn State fact sheet that I got with my CREP package on how to manage different types of knoxious weeds. The one I scanned for you is for Japanese Knotweed.

Hope it is of some help to you. By the pamphlet it looks like one tough invasive species to control. The article recommends "Rodeo" and spraying time is critical. You are approaching that window.

Good Luck.
 

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Discussion Starter #11
Thanks to all for your input. I have read several articles on the subject (that have been sent by members of this forum), and I greatly appreciate your time and effort.
It seems that I'm on the right track, but that I have to be more vigorous with the brew that I'm using and try to apply it to more fully devoloped plants in late summer/early fall.
Based on the current regrowth of the weed, I think we have the perfect scenario for a good kill in September. I'll update the post next spring to let you know the results. Thanks once again to everyone.
 
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