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Microwave Weed Killer Also “Cooks” Pests
Growave is a prototype microwave system that eliminates weeds, weed seeds, and pests. Australian inventor Graham Brodie describes it as a low-cost alternative to non-chemical weed control, and soil treatments like steam or chemical fumigation.
“The microwave system is about 30 percent cheaper than soil fumigation with chemicals and 40 percent cheaper than a soil steam treatment,” says Brodie, a researcher at the University of Melbourne. “As a treatment for emerged weeds, it is about 40 percent higher in cost than herbicides, but about 60 percent cheaper than either steam or flame weeding.”
Brodie began his research when it started becoming clear that more weeds were becoming resistant to herbicides. In 2007 the electrical engineer tore apart a microwave oven and started experimenting. Eventually he came up with a way to confine the energy to a small space.
Growave has been used over wheat, rice, and grasses in different soil types and climates. Unlike herbicides, it even works in the rain and wind. A particularly successful use is to kill weeds under vines without hurting the vines.
The system uses a slow-wave applicator to direct the electromagnetic waves to treat a strip about 6 in. wide. The design creates a very intense, but confined microwave field under the applicator. The microwaves heat up the vegetation, creating internal steam that breaks the cell walls. In demonstrations, crackling, popping and hissing can be heard as weeds are treated. It also kills pathogens near the surface.
Multiple applicators can be used for wider treatment swaths. The depth of soil treatment depends on the applicator design and the operating frequency of the microwave system. The prototype units target a depth of about 1 1/2 to just under 2 1/2 in. Brodie reports that the applicator design can reduce the depth to about 3/4-in. or increase it to around 4-in.
He is currently working on 2 new applications to do spot weeding and also broaden the treatment strips.
“The new applicators are still in the early prototype stage, but are showing good promise,” says Brodie.
While the initial application of the technology is focused on high-value crops like vineyards, Brodie sees potential in other areas. Soil fumigation without chemicals is one. Another is urban playgrounds and footpaths where chemical use is being phased out due to public health concerns.
Brodie recognizes that challenges to adoption remain. The technology needs to be scaled up in terms of power levels and size. The Growave uses a 5 kW generator. Commercial microwave generators as large as 100 kW output can be purchased off-the-shelf.
Contact: FARM SHOW Followup, Growave Pty Ltd. (ph 61 358 339 273; grahamb@unimelb.edu.au; www.growave.ag).

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2021 - Volume #45, Issue #4