Electric discharge weeding works by forcing an electrical current through a plant's stem. The current boils the water inside the plant's cells, bursting the cell walls. This immediately kills the plant. How well a plant conducts electricity determines how easily it will be killed. Typically, any plant with a fairly heavy stem will be affected by this method of control. Plants with soft, pliable stems such as grasses are not as easily affected.
The Annihilator is basically a copper bar that has voltage on it. As long as nothing is touching the bar, nothing happens. As soon as a plant touches the bar, current starts flowing down the plant stem. Electric discharge weeding works for crop plants as well as weeds, so the bar is run just above the crop height. Any weeds that are above the canopy are able to contact the charged bar and many will be killed.