Herbicides 2,4-D & Its Cousins
For all of the attention that the insecticide DDT got, herbicides like 2,4-D became a bigger seller in a few short years. The herbicide 2,4-D came on the market in 1945 for public testing. In 1946, manufacturers sold 631,000 pounds of it. The next year, manufacturers sold 5,315,000 pounds, a 500 percent increase!
Today, the U.S. farmer spends over $11 billion on all pesticides, and 58 percent of that money goes to herbicides, 28 percent to insecticides, eight percent to fungicides and the rest to other chemicals.
It's more important to the American farmer to kill weeds than insects. That means that the development of 2,4-D as the first widely used chemical herbicide in 1944 changed history.
For the first time, farmers had a chemical that they could spray on their fields that would kill more weeds than any amount of cultivating. That is, as long as the field was planted in corn. Plants can be broadly divided into grasses, like bluegrass or corn, and broadleaf plants, like soybeans, flowers and most of the weeds that afflicted corn farmers. 2,4-D affected only the broadleaf plants and left the grasses like corn relatively untouched.
One of the first farmers in the nation to try 2,4-D was Carl H. Leonard of Wayne County, Nebraska. In 1947, Nebraska Farmer magazine reported, "[Last season,] he had cockleburs in the corn rows that got ahead of the cultivators. The weeds were about as tall as the corn in the rows. One spraying of these cockleburs with 2,4-D ended their earthly pilgrimage."
That's probably the most poetic description of the death of a weed as has ever been written. The reporter, Carl Deitemeyer went on to inform his readers about the increased yields Carl got "Leonard's 240 acres of weed-treated corn yielded 50 bushels to the acre. An unsprayed field produced nubbins."
In other fields, the herbicide was tested against conventional tillage practices.
- A control field was cultivated using conventional equipment three times during the growing season and yielded 56.8 bushels per acre.
- A second field was sprayed with 2,4-D only once during the season and yielded 63.1 bushels per acre.
- The third field was sprayed three times and yielded 84.5 bushels per acre.
Like DDT, 2,4-D was called a wonder drug. Nebraska Farmer reported that another field sprayed twice and cultivated "was almost as free of weeds as your kitchen floor."
One of the problems was that there were few commercial pesticide sprayers available. A 1948 book that outlined the myriad kinds of Farm Machinery and Equipment, published by McGraw-Hill, listed a variety of hand sprayers and two engine-powered sprayers for orchards. Neither was suited for row crops like corn.
So, farmers in Nebraska and other states began making their own. Lowell Campbell of Walthill found five pieces of sheet iron and welded them into a tank. He attached that to his tractor, attached hoses from the tank through a pump and to two 10 to 12 foot long pipes. He had spray nozzles attached to the pipes to match the width of his corn rows. The whole contraption cost him $120 to $150.
Other farmers used old 50-gallon drums as their tanks. On a good day, these home-built units could spray 60 acres.
Holly Miller saw first hand the interest that farmers had in 2,4-D and, later, Atrazine. He ran a seed and supply business in York, Nebraska after the war. "We sold several carloads the first year we had it. Of course, I guess the farm people had trust in us in selling what we did."
Scientists, extension agents and farm publications were telling farmers what they knew about the chemical. "2,4 dichlorophenoxyacetic acid" is the full name. It works by disrupting the plant's own growth hormone. Treated plants grow so fast that they can't support themselves and die.
Many of these early articles went into great detail about which weeds were susceptible to the poison, and which weren't. Agronomists recommended dilution rates and how many pounds per acre to apply. But they all cautioned that much more study was needed into the long-term effects of this miracle compound.
Over the years, 2,4-D has remained a popular herbicide. But it's cousins, atrazine (introduced in the 1970s), glyphosate (better known as Roundup from the 1980s) and others have overtaken the old standby. Still, in 2001, 2,4-D was still the fifth most often used herbicide.
Written by Bill Ganzel, the Ganzel Group. A partial bibliography of sources is here.