The Problem of Taproots for Weed Control

Many perennial weeds such as dock and dandelions have a large, dominant root, which grows vertically downwards.  This taproot often acts as a store of energy in the form of carbohydrates, which can be used to grow new shoots after dormancy. Think of the kid growing a carrot top in a dish of water on the windowsill – that small portion of root contains enough energy to produce new leaves.  For the gardener or groundskeeper, this means that hoeing, or any other method removing only the stalks and leaves, are likely insufficient to kill the plant and it will put out new growth.   

Weeds with taproots need to be fully destroyed or removed – either by using a systemically acting form of weed control, or manually, by digging.  This can prove difficult where the roots have grown deep underground or are wedged in between paving stones. 

A Spot Weeding Trial on Burdock 

An area of burdock was treated using our electric spot weeder.  Two weeks later, three plant specimens were dug out. The first had been left untreated to act as a control.  The second and third specimens had taproots of differing sizes; one being typical of burdock plants in the area, the other being larger than other roots observed.  These roots were cut in half and  inspected for signs of damage.  

Results – Can Electricity Kill Weeds with Taproots?

The images below show the results of the electric treatment. 

• The taproot which was of a standard size showed significant decay throughout.  Left in the ground, this root would rot away, and would not form new growth.
• The taproot of a larger size showed damage to the upper part of the root.  Research has shown that killing the top 20% of a taproot is sufficient to prevent any regrowth.