Killing weeds with light a bright idea

It’s probably safe to say that nobody really likes weeds. Unwanted vegetation on the ground, sidewalks, or in gardens can be a nuisance and time-consuming to get rid of.

Apparently, the natural environment doesn’t like weeds either.

“Weeds, noxious weeds particularly, can cause native species to go extinct, so it’s an endangered species problem,” said Dr. Danny Reinke, 412^th Civil Engineering Group, principal scientist for conservation issues. “Every year millions of dollars are spent on weed control in and around military installations."

Eliminating weeds can be done by applying poisonous herbicides, or mechanically, by mowing or tilling. Herbicides can have negative impacts on wildlife populations so having an alternative would be ideal, Reinke said.

A classically-trained botanist, Reinke came up with an idea that would kill weeds without chemicals or heavy equipment that would disturb the ground. He submitted his idea to the Edwards AFB Small Business Innovation Research office, which sent the proposal up to Air Force Materiel Command. His concept was selected for funding and the Air Force solicited a couple small businesses to make the concept become reality.

The result is the NatureZap, a hand-held device that essentially kills weeds using light.

“The reason a plant is green is because it reflects green light and for photosynthesis a plant uses blue light. Overloading the blue frequency range disrupts the enzymes in the photosynthetic process, which cuts off the food supply to the plant and it dies. Some herbicides overload the metabolic system of the plant and makes the weed burn from the inside out. I thought that overloading the photosynthetic system would maybe do the same thing,” Reinke said.

NatureZap is made by Global Neighbor, Inc., the company the Air Force granted funds to as part of the SBIR selection. By selectively overloading the plant with light highly concentrated in the blue range, the NatureZap disables the photosynthetic system and the plant dies. 

“One of the problems using herbicides like DDT, which killed insects really well, but it was concentrated in the shells of eggs of birds that ate the insects that were killed. Using toxic chemicals in general is probably not a good approach.”

Reinke added the advantage is a source that doesn’t use any toxic chemicals or disturbs soil, which encourages weeds to grow. The NatureZap is also relatively cheap and plugs in to a normal outlet to charge.

Reinke also said the NatureZap will help in compliance with the Sikes Act Improvement Amendments of 1997, which requires military bases to promote planning, development, maintenance, and coordination of wildlife, fish, and game conservation and rehabilitation. The DOD also has a goal for all military bases to reduce the amount of toxic chemicals used by 50 percent. Edwards, like other Air Force bases, complies with these requirements by implementation of an Integrated Natural Resources Management Plan, which protects the environment in concert with the Edwards mission by ensuring the natural habitat and wildlife are sustained.

“What we like about [NatureZap], from an environmental perspective, there are no toxic chemicals, no toxic residue, no ground disturbance. All those are good things and help us when we meet our requirement under the Sikes Act. Endangered species don’t do well with weeds,” said Reinke.

The 412^th Civil Engineering Group has three NatureZaps that are basically a “touch-up” tool for small weeds and around yards. Once charged, the NatureZap can be pointed at a weed and in a few seconds the plant begins to turn brown and die. It works better when the entire weed can be illuminated. The current units treat an area about the size of a softball according to Reinke.

Currently, Edwards AFB is in “Phase 2” of the Air Force Small Business Innovation Research venture with Global Neighbor, Inc. and are working with the company on getting some new working prototypes. The company is developing a device that can cover more space and be pulled behind a tractor. They’re also working on technology where the light will turn on only when it sees vegetation.

The Air Force SBIR and Small Business Technology Transfer programs are mission-oriented programs that integrate the needs and requirements of the Air Force through research and development topics that have military and commercial potential. They provide more than $300 million in funding for research and development activities by small businesses annually. With this budget, the Air Force funds research from the early stages of concept development until it transitions to military or commercial use.