Their names almost make them sound like the villains in an old John Wayne movie: Palmer Amaranth, Tall Waterhemp and Giant Ragweed.

In reality, they’re among the worst invaders in a farmer’s soybean fields — prolific weeds that rob our food crops of moisture and nutrients, depress our yields and resist many forms of herbicide.

To fight them, we need the best technology available — and on Oct. 31, the Environmental Protection Agency (EPA) tossed us a lifeline.

Regulators extended for two years our ability to use a form of a soybean that resists dicamba, a traditional crop-protection product that helps us defeat these terrible weeds....