From: Andy Soos, ENN
Published November 14, 2011 12:51 PM

Weed Ray Guns

Weed control is the botanical component of pest control, using physical and chemical methods to stop weeds from reaching a mature stage of growth when they could be harmful to domesticated plants and livestock. In order to reduce weed growth, many weed control strategies have been developed in order to contain the growth and spread of weeds. The most basic technique is plowing or manual weeding which cuts the roots of annual weeds. Today, chemical weed killers known as herbicides are widely used. So what is there a better way? The Air Force is requesting proposals/research topics to develop a device that uses directed energy technology to prevent and abate unwanted plants (weeds) in areas that require control or defoliation. The purpose of this system will be the removal of unwanted plants and keep seeds from germinating.


In domestic gardens, methods of weed control include covering an area of ground with several layers of wet newspaper or one black plastic sheet for several weeks. In the case of using wet newspaper, the multiple layers prevent light from reaching all plants beneath, which kills them. Saturating the newspaper with water daily speeds the decomposition of the dead plants. Any weed seeds that start to sprout because of the water will also be deprived of sunlight, be killed, and decompose. After several weeks, all germinating weed seeds present in the ground should be dead.  

Weed control can also be achieved by the use of herbicides. Selective herbicides kill certain targets while leaving the desired crop relatively unharmed. Some of these act by interfering with the growth of the weed and are often based on plant hormones. Herbicides are generally classified as follows;

Contact herbicides destroy only that plant tissue in contact with the chemical spray. Generally, these are the fastest acting herbicides. They are ineffective on perennial plants that are able to re-grow from roots or tubers.

Systemic herbicides are foliar-applied and are translocated through the plant and destroy a greater amount of the plant tissue. Modern herbicides such as glyphosate are designed to leave no harmful residue in the soil.

Soil-borne herbicides are applied to the soil and are taken up by the roots of the target plant.

Pre-emergent herbicides are applied to the soil and prevent germination or early growth of weed seeds.

Every year millions of dollars are spent on weed control in and around military installations. Weed control and abatement can either be performed chemically; by applying poisonous herbicides, or mechanically; by mowing or tilling. Herbicides can be grouped by activity, use, chemical family, mode of action, or type of vegetation controlled.  Herbicide use generally has negative impacts on bird populations, although the impacts are highly variable and often require extensive field studies to predict accurately.

Having a cost effective device that eliminates the use of herbicides or reduces the amount of machinery could extensively save money and protect wildlife at the same time. Private industry has been actively engaged in the research, development, and deployment of various physical control technologies utilizing microwave radiation (as heat), lasers, and sound to deter, disrupt, deny, or degrade the desired objective.

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