Monday, September 17, 2012

Noxious Weeds by Mary Beth Mainero

Last year I took the Native Plant Class with Patti O’Neal, Research Associate at the CSU Extension in Jefferson County. I was eager to learn all about the beautiful wildflowers on my property. Lo and behold they turn out to be Noxious Weeds! Not all, but many.
Did you know that Colorado has a Noxious Weed Law (CRS 35-5.5 et al) that requires all homeowners to control and eradicate noxious weeds on their property? This is a civic obligation, besides voting and jury duty!
These weeds are broken down into three lists (A, B and C) designating their levels of invasiveness and environmental damage to our lands. To better educate yourself, you can go to , to see if you have any of these weeds and how to get rid of them. (Photos were taken from this site.)
Diffuse Knapweed

What I am seeing right now in my neighborhood (Evergreen) and on my walks in Jeffco Open Space are an abundance of Diffuse knapweed (white), Yellow and Dalmatian toadflax and Common mullein.  That knapweed takes over so quickly, so pull and/or spray. I had to get a licensed contractor this year to get rid of my knapweed, because I had so many and the chemical used was not available to homeowners.  If you do use a suggested chemical for homeowners use, please read the entire label, twice. Mowing is not suggested because it causes new growth from the crown of the plant.

It is important that you learn the difference between Dalmation toadflax and Yellow toadflax because one you can pull (Dalmation) and the other (Yellow) you cannot. If the Yellow toadflax is pulled, the fragmented roots will produce more plants. A good reference is,

Dalmation Toadflax 1

Yellow Toadflax

Dalmation Toadflax 2

Keep an eye on Common mullein, otherwise it takes over your property like little soldiers going to battle. You need to battle this plant…….”Off with their heads”! When you see those yellow flowers/seeds it is time to get out there and cut them off and bag them. If not each plant can produce 180,000 seeds. This weed can be pulled when young, in rosette form or old, when it can stand 8 feet tall. It is a biennial.

Commom Mullein 3

Commom Mullein 1

Commom Mullein 2

And don’t forget that when you do remove these weeds you need then to revegetate with native plants or grasses. Now is the time to plan this with the coming of the first snowfall of the season. Are you ready? 
More information can be found at and

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