Farmers are returning to tilling and using older, more toxic herbicides to control weeds.

FORBES: Survival Instinct: Businesses Must Watch Out For Mother Nature

Using a herbicide to control weeds--especially in the initial growing stages--is vital to the health of a crop, because weeds usurp water, nutrients and space.

FORBES: Commentary

Therefore growers strive to control weeds in their fields.

FORBES: Magazine Article

For example, researchers in Arizona are using real-time kinematic global positioning systems, an ultra-precise version of GPS that can measure positions with sub-inch accuracy levels, to control weeds in cotton fields with steel cultivators.

FORBES: American Agriculture's 'Sputnik Moment'

Most of these new varieties are designed to be resistant to pests and diseases, or to be resistant to herbicides, so that farmers can more effectively control weeds while adopting more environment-friendly no-till farming practices and more benign herbicides.

FORBES: Move up http://i.forbesimg.com t Move down

" According to Air Force documents, this project calls for "a device that uses directed energy technology to prevent and abate unwanted plants (weeds) in areas that require control or defoliation.

ENGADGET: The Air Force will give you $150,000 to blast its weeds with a laser

's Concern brand is one of two dozen companies offering an alternative to Turf Builder in a lawn fertilizer weed-control product that is derived from corn (but kills weeds like crabgrass only as they germinate).

FORBES: Magazine Article