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
1 rating

Monday - April 01, 2013

From: Brisbane, Australia
Region: Other
Topic: Invasive Plants, Non-Natives, Problem Plants, Herbs/Forbs
Title: Dietes bicolor invasive from Brisbane Australia
Answered by: Barbara Medford

QUESTION:

We have dietes bicolor growing in our garden. I am changing the type of garden and cannot seem to kill it. I've dugged it out, spent too many weekends pulling out every new shoot, used poison, but to no effect. I cannot replant this garden until I can get rid of this plant. Any suggestions?

ANSWER:

We are at something of a disadvantage in trying to answer your question. The Lady Bird Johnson Wildflower Center (home of Mr. Smarty Plants) is committed to recommending the growth, propagation and protection of plants native to North America. Dietes bicolor (African iris) is native to, well, South Africa, and therefore  to neither North America nor Australia. It is widely grown in Central Texas, though of course not at the Wildflower Center. Since we have no experience with it, we were not aware of any tendency to invasiveness. The main problem in getting rid of it is that its root are rhizomes.

Rhizomes are horizontal underground stems that strike new roots out of their nodes, down into the soil, and that shoot new stems out of their nodes, up to the surface. This rhizome activity represents a form of plant reproduction. The irrepressible nature of much of the vegetation you'll find on invasive plants lists is due to the vigor of the rhizomes of these aggressive plants.

Looking at these images of rhizomes will help you understand how difficult your task may be. If the plants you have in your garden are not too large, you may be able to dig out the whole network of roots in one mighty shovelful, but probably not.  After removing as much as possible, and discarding the clump of dirt with the rhizomes in it where they roots won't be able to reproduce yet again, try to kill any remaining portion of the rootlets left behind. Our practice in getting rid of plants that obnoxious is to obtain a small bottle of a wide spectrum herbicide that will kill just about anything, along with some small sponge disposable paintbrushes. If you find a small new plant coming up, cut it off as close to the soil as you can, and then paint the cut root end with some of the herbicide. You must do this quickly after cutting before the rhizome heals itself over to protect the rest of the plant. Properly administered, that herbicide should be able to destroy at least that little fragment of the plant. Prepare to repeat this many times before the rhizomes finally are defeated.

 

More Invasive Plants Questions

Invasive Cissus trifoliata in Dallas
May 25, 2011 - I have finally identified an invasive, stinky vine in my urban landscape as Cissus trifoliata. It was waxy leaves, small greenish flowers, and small black berries. It appears to spread with undergrou...
view the full question and answer

Reference for native critical populations from York, PA
May 25, 2010 - I have recently read a naysayer of native gardening. He states that native garden plants usually do not have the critical population size to be self-perpetuating. He says that one could better help t...
view the full question and answer

Why are invasive, non-natives being sold from Hillsboro TX
August 03, 2012 - Why are nurseries allowed to grow and sell seed from invasive non-native plants like: johnson grass, bermuda grass, and king ranch bluestem? Many times when I contact a nursery or seed distributor as...
view the full question and answer

Official list of invasive plants in Texas.
January 25, 2008 - Is there an "official" invasive / noxious weed list for Texas? I have found several lists, but I wanted to know if there was one truly accepted list for Texas. If not, what would be the #1 list yo...
view the full question and answer

Non-native invasive Siebold viburnum from Isleboro ME
June 17, 2012 - I was given several small Siebold Viburnum for planting on my Maine property. Even though it is often for sale in nurseries, I'm aware it is listed as invasive in several eastern states. Shouldn't I...
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