En EspaŅol

Q. Who is Mr. Smarty Plants?

A: There are those who suspect Wildflower Center volunteers are the culpable and capable culprits. Yet, others think staff members play some, albeit small, role. You can torture us with your plant questions, but we will never reveal the Green Guru's secret identity.

Help us grow by giving to the Plant Database Fund or by becoming a member

Did you know you can access the Native Plant Information Network with your web-enabled smartphone?

Share

Ask Mr. Smarty Plants

Ask Mr. Smarty Plants is a free service provided by the staff and volunteers at the Lady Bird Johnson Wildflower Center.

Search Smarty Plants
    
 
See a list of all Smarty Plants questions
Can't find the answer in our existing FAQs, submit a question to Mr. Smarty Plants.
Need help with plant identification, visit the plant identification page.
 
rate this answer
Not Yet Rated

Monday - July 28, 2008

From: Chicago, IL
Region: Midwest
Topic: Invasive Plants
Title: Getting rid of Polygonum punctatum (dotted smartweed)
Answered by: Nan Hampton

QUESTION:

Dear Mr. Smarty Plants, After much online research, my property has been invaded by what I believe to be Persicaria polygonum punctata, more commonly known as dotted smartweed. I have tried horticultural vinegar but it only curled the leaves. Additionally, I have read that horticultural vinegar detrimentally changes the soil. These plants become at least three feet tall so it's hard to spray all parts of it. I have thought of covering them with clear plastic sheeting but don't know if that is enough heat to kill the roots. I feel my last resort is glyphosate, of which I have heard pros and cons. Digging them out is as horrendous as trying to comb out knotted hair and I do not have the time nor energy as they are everywhere. As I have said, I have been all over the Web looking for an answer as to how to kill these plants. Do you have any suggestions? I would really appreciate any advice you can provide. Jo

ANSWER:

I assume you mean Polygonum punctatum var. punctatum (syn.=Persicaria punctata)(dotted smartweed), a plant native to North America. Another common name is water smartweed. Or, are you talking about Polygonum persicaria (spotted ladysthumb). This is an introduced species. Whichever one it is, the treatment will be the same. The most environmental friendly way, of course, would be to dig them out or pull them up. Alternatively, instead of spraying them you can cut them off near the ground and carefully paint or inject the cut stalk with herbicide. This would put the herbicide where it would do the most good and would be the least harmful to other plants and to the environment. If you spray them, you run the risk of harming other plants nearby that you want to save. Consult with the Cook County Extension Service or visit a reputable garden nursery for advice on the best herbicide to use. Please read carefully all instructions that come with the chemical and follow the safety guidelines to protect yourself and the environment.
 

More Invasive Plants Questions

Transplanting Virginia creeper
September 02, 2008 - I have a large Virginia creeper plant approximately 15 feet in length. Is it possible to transplant the whole thing without killing it? If so how do I care for it after it has been moved? Thank yo...
view the full question and answer

Evergreen hedge for constant rain
June 24, 2008 - We live in Washington State up north by Canadian border. We need a hedge that will survive the constant rain. We have tried cedar. They seem to turn brown and die,one at a time so we keep replacing th...
view the full question and answer

Native vs. Invasive Experiment
July 01, 2008 - I asked you earlier about my group's experiment on native vs. invasive plants in Valdosta. Here are what we chose to work with..native: spiderwort (Tradescantia ohiensis) and invasive: wild taro (Col...
view the full question and answer

Will native Galium aparine be a problem in Austin garden?
March 25, 2014 - Should I be concerned that my yard is overrun with "sticky weed" (Galium aparine) in the early spring? Specifically, about five years ago I undertook converting about half my back yard into a na...
view the full question and answer

Control of King Ranch Bluestem (Bothriochloa ischaemum)
November 21, 2007 - What is the best way to get rid of King Ranch Grass (an invasive plant) on my half acre property? I felt like mowing just encouraged more seed heads to pop up.
view the full question and answer

Smarty Plants's Facebook profile Support the Wildflower Center by Donating Online or Becoming a Member today.

Mr. Smarty Plants wants you to be his Facebook friend. Click the Facebook icon to add yourself to Mr. Smarty Plants list of friends.
E-NEWSLETTER | BECOME A MEMBER | DONATE NOW | MEDIA | SITEMAP
© 2014 Lady Bird Johnson Wildflower Center