En EspaŅol
Share

Ask Mr. Smarty Plants

Mr. Smarty Plants - Removing three-seeded mercury in Austin

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 - November 09, 2009

From: Austin, TX
Region: Southwest
Topic: Invasive Plants
Title: Removing three-seeded mercury in Austin
Answered by: Barbara Medford

QUESTION:

How can I get rid of Three Seeded Mercury (Acalypha phleoides)? Even if I try to dig it up, the roots go down forever and it ends up just breaking at 6-8" down. Just breaking it off at the surface, makes it grow even lusher. I've been trying for years to get rid of it and it's just spreading and taking over more of the yard. The "yard" is horse herb (aka straggler daisy) and other plants that come up that I like. I don't mow. I just pull out what I don't like. But this one weed is defeating me.

ANSWER:

Well, you may have to learn to like Acalypha phleoides (shrubby copperleaf), or be more aggressive. It is native to this part of the state, and therefore very adapted to the rainfall, climate and soil. Since it is perennial, just pulling it off the root is not going to stop it from coming back up, as you have already pointed out. You can't spray it with herbicide, as it would kill all the other dicots or broad-leaved plants (like the straggler daisy) that you already have. If you buy a spray that is for monocots, or grasses, it won't bother the three-seeded mercury, but it could kill some native grasses that you have been cultivating.

The first thing to do is make sure it never has an opportunity to go to seed. Even though it is a perennial that can come up from the roots, it will also propagate itself by the seeds on those tall bracts. This might be a time to break your rule about never mowing; if you mow it before it can seed, and keep mowing it as it sends up more bracts to try to seed again, you might just wear out the food stored in the roots. Doing this for several weeks when the plant is trying to bloom, and thus set seed, could greatly alleviate your problem. 

Beyond that is the somewhat labor-intensive, hands and knees on the ground, method of painting the cut stem with a wide spectrum herbicide. Begin with a small bottle of the herbicide and some disposable sponge brushes. Cut each stalk off near the root and quickly, within five minutes before the stalk starts to heal over to protect the roots, paint the cut edge with the herbicide. Be very careful, spilling this could contaminate the soil and kill the other plants, broad-leaf and grasses, and don't spray, for the same reason. This plant is monoecious, which means it has both male and female flowers on each plant, and each plant can carry on creating more plants with no outside help. 

From our Native Plant Image Gallery:


Acalypha phleoides

Acalypha phleoides

Acalypha phleoides

 

 

 

More Invasive Plants Questions

Removal of non-native zoysia grass from Burgettstown PA
September 12, 2013 - What is the most effective method of killing zoysia grass? We bought a house that sits in the center of four acres of mature zoysia. It looks beautiful, however, despite our best efforts at "weeding...
view the full question and answer

Plants to replace Polygonum cuspidatum ( Japanese knotweed)
August 10, 2013 - I live in a heavily wooed area of Chippewa Falls, WI. Our property is covered with Giant Japanese Knot Weed. We have been trying to get rid of it for years. We are finally going to try using the dr...
view the full question and answer

Source for Saltmarsh cordgrass from Houston
April 16, 2013 - I work for a consulting firm and we are looking to do more of our wetland creation/restoration. Do you know where one can purchased Spartina alterniflora?
view the full question and answer

Control of English ivy
November 27, 2007 - I need to know if there is a way to kill, or contain, English Ivy that was planted as groundcover next door. Despite my discouragement, my next door neighbor planted English Ivy as groundcover all alo...
view the full question and answer

Landscaping in the Southern California desert.
October 16, 2007 - We are located in southern California in Lake Havasu. I'm trying to landscape sloping areas. I have arrow weeds (Pluchea sericea) and want to get rid of them permanently. How can I achieve this or...
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