Dad had mixed feelings about his workhorse teams. At their best, they worked in perfect harmony and at their worst could run roughshod.

Looking back, it’s surprising the amount of change Dad saw from the driver’s seat — be it the switch from horses to horsepower and the arrival of hybrid corn seed to tiled fields.

He remained most comfortable on his WD. Thistles, button weeds, cockleburs and quack grass were mortal enemies. A cultivator couldn’t remove all broadleaves, which made hoeing necessary.

It did not appeal to his children, who unanimously agreed that it was about the worst chore imaginable. The herbicide 2, 4-D represented a weed control revolution of sorts.

The chemical was invented by British scientists who sought a way to increase food production in World War II by eliminating weed pressure. Commercial U.S. sales began in 1946 and made the chemical the most popular herbicide for several years. More than 1,500 weed control product contain some form of 2, 4-D today.

The product effectively forces weeds to kill themselves by growing wildly out of control, which amounts to vegetative cancer.

Its impact on human health has been debated for several decades. A health study involving Nebraska farmers who used 2, 4-D found that they suffered more non-Hodgkin’s lymphoma than the general population. A follow-up study done by Dow Chemical scientists found no increase in non-Hodgkin’s lymphoma cases, but did note an increase in Lou Gehrig’s disease cases.

The International Agency for Research on Cancer, which is somewhat a neutral arbitrator, listed 2, 4-D as "a possible cause’’ of cancer.

Rumors were rife in farm country in the 1960s and ‘70s about salespeople who convinced farmers about the safety of their herbicide products by drinking a glass containing it as part of their sales pitches.

The tactic is still being used by defenders of glyphosate’s safety. Dr. Patrick Moore, a staunch defender of Roundup against claims the product causes cancer, has appeared on television insisting that people could drink a quart of the herbicide and it wouldn’t cause damage. Moore smartly refused when challenged to do so.

The case for and against Roundup is debated among scientists and has entered the U.S. court system. Monsanto, the product’s manufacturer, currently faces more than 13,000 lawsuits and possibly billions in settlements.

Its defenders argue that the product is safe, but recent juries haven’t agreed. A plaintiff recently won a $78.5 million judgment against Monsanto. If that award is upheld and plaintiffs win their lawsuits, the firm could be devastated financially. More than 1.4 billion pounds of Roundup was applied in 160 countries in 2017.

Dad, who had seen grasshoppers destroy crops during the Dust Bowl years, welcomed DDT, which is shorthand for dichloro-diphenyl-trichloroethane. Created in the 1940s to control malaria, typhoid and other insect-carried diseases, DDT was so popular that its widespread use quickly led to insects developing resistance to the pesticide. By 1970, the U.S. Department of Agriculture — the Environmental Protection Agency hadn’t been established yet — started regulating the use of DDT because of its impact on the environment and humans. Bald eagles were threatened with extinction by 1970 because DDT caused eagle eggs to be overly fragile.

In 1972, the newly formed EPA banned DDT. It was a controversial, if necessary, move.

The jury is still out on Roundup. Opponents and defenders are equally vocal, but not all are well informed.

There is but one certainty: new herbicides and pesticides will come on the market and insects and weeds will continue to develop resistance to them.

I highly doubt that we’ll ever again see armies of farm children hoeing and pulling weeds.