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Is this Knotwood? #873262

Asked June 15, 2024, 5:27 PM EDT

I have a 'tree" that i was told was a Japanese knot wood. I have been unable to get rid of this thing. Can you please help me identify it and let me know what the best way to get rid of it? I've read that the best thing to do is use a 20% Glyphosate Herbicide during fall and winter to help get rid of it. ???? I cut this thing back about 3 weeks ago and it is just as big now. Seems to thrive in the heat and humidity. uggh

Genesee County Michigan

Expert Response

Hello,
This does not look like Japanese Knotweed.  Instead, it appears to be northern catalpa.  (https://www.fs.usda.gov/wildflowers/plant-of-the-week/Catalpa-speciosa.shtml)
Cutting it back as far as you can and painting with a gel-formulation of glyphosate immediately after cutting should kill it.  It can take a little time and possibly another application later in the summer/early fall.
Thank you for contacting Ask Extension.
Ruth
An Ask Extension Expert Replied June 16, 2024, 9:12 AM EDT
This plant or tree doesn't produce flowers or seeds.  It's just massive amounts of those big leaves.  It is very soft or fibrous like a cottonwood when I cut it and grows very very quickly.   Thank you so much for your help.

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From: ask=<personal data hidden> <ask=<personal data hidden>> on behalf of Ask Extension <<personal data hidden>>
Sent: Sunday, June 16, 2024 9:12:08 AM
To: Michelle Whitehead <<personal data hidden>>
Subject: Re: Is this Knotwood? (#0143180)
 
The Question Asker Replied June 16, 2024, 2:33 PM EDT
Hello,
I am confident that my identification is correct.  The plant will not produce flowers or seeds if it is not mature.  Catalpa do grow very vigorously. I stand by my recommendation to treat with a gel formulation of glyphosate immediately after cuts are made.  This should be done by "painting" the cuts with the herbicide. 
Ruth
An Ask Extension Expert Replied June 16, 2024, 10:11 PM EDT
Thank you!

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From: ask=<personal data hidden> <ask=<personal data hidden>> on behalf of Ask Extension <<personal data hidden>>
Sent: Sunday, June 16, 2024 10:11:38 PM
To: Michelle Whitehead <<personal data hidden>>
Subject: Re: Is this Knotwood? (#0143180)
 
The Question Asker Replied June 17, 2024, 6:15 AM EDT
Last question I promise . . . would Round up Weed and grass killer work?  it says it has 2% glyphosate.
From: ask=<personal data hidden> <ask=<personal data hidden>> on behalf of Ask Extension <<personal data hidden>>
Sent: Sunday, June 16, 2024 10:11 PM
To: Michelle Whitehead <<personal data hidden>>
Subject: Re: Is this Knotwood? (#0143180)
 
The Question Asker Replied June 17, 2024, 10:53 AM EDT
It will probably work pretty well, though the gel might be better because you can concentrate it where you need to.  What you have is a little stronger than the gel, though, so as long as you really wet the cut surface and are not concerned about plants around that you might be killing with drift.  (Should plan to apply this on a windless day regardless).  Here is an article about all of the glyphosate products out there: https://www.canr.msu.edu/news/understanding_roundup_products
Ruth
An Ask Extension Expert Replied June 17, 2024, 3:48 PM EDT
Thank you so much for your time and expertise.   I've been trying to get rid of this stuff the last couple of years  

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From: ask=<personal data hidden> <ask=<personal data hidden>> on behalf of Ask Extension <<personal data hidden>>
Sent: Monday, June 17, 2024 3:48:08 PM
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Subject: Re: Is this Knotwood? (#0143180)
 
The Question Asker Replied June 17, 2024, 4:05 PM EDT

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