Rent Shop Volunteer Join

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

Please forgive us, but Mr. Smarty Plants has been overwhelmed by a flood of mail and must take a break for awhile to catch up. We hope to be accepting new questions again soon. Thank you!

Need help with plant identification, visit the plant identification page.

 
rate this answer
Not Yet Rated

Tuesday - March 10, 2009

From: Burnaby, BC
Region: Canada
Topic: Invasive Plants
Title: Controlling Pickerel weed (Pontederia cordata) in British Columbia
Answered by: Nan Hampton

QUESTION:

Hello, I am emailing from the west coast of Canada, Vancouver, and I have a plant question regarding a species you have listed on your website. We have recently discovered Pontederia cordata L. Pickerel weed in a natural lake. On searching on-line, the plant is native to parts of the US but as a garden variety. Though it may not be officially invasive here, the garden variety has escaped into a natural area with fish and other wildlife value. As such, we would like to be proactive and control the species before it naturally spreads out of control. From your knowledge, what is the best way to control the species? Once the root system is established, I suppose we have to 'dig up' the roots to eradicate the plant? Any tips you can provide for this, so the work can be done with as little disturbance, would be greatly appreciated. As well, we are hoping to control spread of the plant by cutting off flowers before they seed. Any further suggestions or comments so we can control this plant is greatly appreciated! Kindly, Melinda Yong Environmental Technician

ANSWER:

Pontederia cordata (pickerelweed) is distributed over the eastern half of North America, including Quebec and Ontario.  There is also a population in Oregon.  The population in Oregon may be of a garden variety, but the ones in the eastern half of North America are wild native populations.  Nevertheless, P. cordata is included in the Southern Weed Science Society's Weeds of the United States and Canada list as an invasive and/or noxious weed.  I certainly understand your concern to find it in your lake—even though it is native to North America, it is not native to British Columbia.  Removing the flowers before seed set is certainly an important measure to use.  One recommendation for controlling emersed rooted aquatic weeds (such as P. cordata) given in Aquatic Weed Management: Control Methods by J. L. Shelton and T. R. Murphy from the the Southern Regional Aquaculture Center is to deepen the edges of the pond or lake since these emersed plants generally grow in shallow water (<2 feet).  This might or might not be practical depending on the size of your lake, but certainly you are going to have to use some mechanical or chemical means to remove or kill the plants and their roots.  According to Aquaplant (Texas Agrilife Extension Service, Dept. of Wildlife and Fisheries Sciences, Texas A&M University) mechanical or chemical control are the only control methods since there is no known biological control for pickerelweed.  You can read about various mechanical and physical control methods, as well as chemical controls, from the US Army's Aquatic Plant Information System Online.  The mechanical method with least disturbance to the lake is, of course, hand cutting and digging to remove roots and rhizomes.  Monitoring and diligence will be required afterwards to keep the plant under control.

Pontederia cordata

Pontederia cordata

Pontederia cordata

 

 

More Invasive Plants Questions

Non-native Star Jasmine poisonous to dogs from Dallas
May 20, 2013 - Is star jasmine poisonous to dogs?
view the full question and answer

What is causing leaf drop on oak in Morgan Hill CA?
June 23, 2010 - Dear Mr Smarty Plants: We have a large, young Valley Oak (about 20 yrs) which is dropping leaves even now in early summer. I have a feeling that the problem might be an invasive weed that is flourishi...
view the full question and answer

Fast growing, possibly invasive trees for South Carolina
July 12, 2007 - What fast growing trees would you suggest for South Carolina? We are heavy clay and the pecan trees we planted don't see to be too happy here. We are looking at the yellow poplar and the empress tre...
view the full question and answer

Should the herbicide Ornamec 170 be used on unwanted grasses?
March 15, 2012 - I have a lovely wildflower garden in a field behind my house; unfortunately, the wildflowers are being smothered by grasses. I understand that Ornamec 170 can be used to control grasses in wildflower...
view the full question and answer

Non-native invasive henbit from Round Rock TX
April 27, 2013 - I've read in this book "Native Alternatives to Invasive Plants" that Henbit is an invasive plant in Texas. I've also read that it provides an early source of nectar to bees and butterflies when li...
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.