[Retric]

Lasers are going to use far less energy than pesticides per plant killed.

A 20W laser (120W input) can cut 3/4th inch thick pine at 6 inches a minute. For burning through a young weeds stem you’re talking fractions of a second per plant. It’s likely the motor and other electronics ends up using more energy than the laser.

Mechanical methods are going to be a lot more complex and thus have significantly more maintenance issues.

[henearkr]

You are comparing nothing here. You forgot one whole leg of the comparison... i.e. the pesticide production footprint.

[Retric]

I was comparing it to the equipment used to carry the laser or pesticide. The application of pesticide itself is ~2-3 orders of magnitude larger the laser before you consider manufacturing or transportation.

The laser itself is a rounding error here, what matters is the other equipment involved.