How can I eliminate Coltsfoot from my asparagus patch?

Question:

How can I eliminate Coltsfoot from my asparagus patch? I tried digging it out by the roots, but that made it spread more. It has also invaded my blueberry bushes.

Answer:

Jonathan Foster, Special Project Assistant 

Coltsfoot can be quite a pain when it gets established. Physical removal can help reduce the weed’s presence, but not eliminate it entirely–as you learned it will resprout readily from any bit of broken rhizome left in the soil after the plant is pulled.

Washington State Weed Control Board page on Coltsfoot

Penn State Extension page on chemical controls for Coltsfoot

As you’ll see in the above resources, chemical control is the most effective method of removal. This will be tricky, as you’re dealing with established asparagus and blueberry interspersed with the coltsfoot, and several of the pesticides listed are non-specific. One of my colleagues recently had a similar conversation (in that instance, with vetch growing in an asparagus bed) with our UMaine Extension specialist, David Hanley, and he recommended dicamba for weed control when growing asparagus; it is listed as an option for coltsfoot in the PSU resource above. The advice from Dr. Hanley was that it “can be applied either before the spears emerge, or just after she takes the last cutting, being sure that no spears are exposed.”

* As always when using pesticides or chemical additives of any kind in the garden, take special care to read and follow the instructions carefully and exactly. *