Host an Event Volunteer Join Tickets

Support the plant database you love!

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

Reply on Carolina Jasmine from San Antonio
March 06, 2009 - Thank you for your prompt reply to my question from San Antonio about removal of Carolina Jasmine. Just one note. In the "rate this answer" section my cursor dropped. I meant to give you four stars....
view the full question and answer

Non-native pothos ivy from Houston
May 30, 2013 - My pothos devils ivy is about 5 years old and grows outside. A couple of years ago its leaves became spectacularly large, like 12" wide and its stalk about 1 - 2" wide. A couple of years ago i gui...
view the full question and answer

Percentage of plants native to U.S.
June 22, 2007 - About 50% of the plant species in Hawaii are naturalized, invasive, aliens (from other places). What are equivalent statistics for the lower 48 states (continental US) as a whole?
view the full question and answer

Flowering landscape plants for Montgomery TX
March 07, 2013 - Hello I live in Montgomery TX. I am looking for low growing evergreen flowering plants for the front of my three deep beds. The first plant closest to the foundation is loropetalum, then I have a blue...
view the full question and answer

Control methods for Cenchrus spinifex, Coastal sandbur
September 22, 2006 - I have some of the nicest, thickest, greenest grassburs in the county of Erath. What is the best and quickest way to get rid of them? I have heard of a product called cornmeal gluten. Any info appreci...
view the full question and answer

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