Vegetation growing up into an Electric Fence will significantly affect the performance of the fence in several ways.

• Power Drain. -When grass, weeds or branches touch the electric fence, they are green and full of moisture so create a path for electricity to leak into the ground. this reduces the voltage on the fence making it less effective.
  The quantity of vegetation does matter, consider a pipe with just one small hole in it - the capacity to transmit water will not be affected much but fill that pipe with many holes and little water will get through. The analogy is the same - one leaf will have no effect but a complete bush will.
• Reduced Shock Intensity, -The more vegetaion that comes into contact with the fence the weaker the shock delivered to the animals. This may allow the target animals to push thorough the fence without receiving a strong deterent.
• Short-Circuiting. - In extreme cases, thick or wet foliage will short circuit the fence hence preventing it from delivering any useful energy.
• Increased Energy Consumption. - The majority of energisers will work harder to compensate for any powerloss due to vegetation leading to higher energy consumption and potentially reducing the life of a battery and the lifespan of the energiser.
• Fire Hazard. - In dry conditions a highly charged fence in contact with dry vegetation can generate sparks posing a fire risk. These high energy Weedburner type energisers are old technology and not readily available.

Solutions.

• Use your fence tester to identify problem areas.

• Regularly trim vegetation beneath and around the fence.

• Use Low-impedence Energisers which can handle some vegetation challenge without losing effectiveness. They are designed to compensate (to a dgree) by releasing more of the stored energy to the fence. These are the type commonly available now.

• Place a Weed Barrier below the fence line. These effectively prevent the growth of vegetation. Particularly effective under netting type fences where the live wires are close to the ground. This is a long term solution.

• Apply broad spectrum herbicides (Glyphosate, Paraquat) or flame weeders to kill weeds. Generally a short term fix.

• Raise the bottom wire slightly to reduce contact.

• Utilise Weedburning energisers. Old technology and no longer readily available. May cause fires.