Scientists develop microwave device to kill weeds

Australian scientists on an experimental farm have developed a revolutionary method of killing weeds using microwaves.

Dr Graham Brodie, a food and agriculture lecturer at the University of Melbourne's agricultural campus, an experimental farm in Dookie, 226 km north of Melbourne, has developed the method of using trailer-mounted microwave generators to combat weeds.

According to the reporting of Xinhuanet, a bank of four microwave generators, approximately double the power of an average microwave oven, is put on the back of the trailer which is then driven over the weeds, killing them immediately.

The generators ‘cook’ the weeds from the inside, just as a microwave oven does with food, leaving them wilted and dead rather than burned or shrivelled.

The range of radiation is limited to between two and three centimeters, enough to kill the weeds while making the device safe to operate.

"It kills the plants almost instantaneously," Brodie told the university's internal publication on Wednesday.

"The big gain is that we can kill weeds without herbicides, so we don't have to worry about weeds that are now evolving chemical resistances, and it kills the seeds left in the soil too so the weeds don't grow back.

"It can also be done in any weather, it isn't a fire hazard, and farmers can sow their crops immediately instead of having to wait for the herbicide to clear."

The device could save the Australian agricultural industry more than three billion US dollars which is spent by farmers on herbicides every year.

Testing of Brodie's device found that it was marginally more expensive than using herbicides but had added benefits such being longer lasting, enriching soil and killing pests such as snails, fungi and parasites.

Brodie said the microwaves did kill worms that were within five centimeters of the surface but deeper-lying worms were unharmed.

The device has been patented and will be subjected to a large-scale trial.