Organic Agriculture & Pesticides

In the last quarter of the 20th century, consumers and a few farmers starting demanding what they considered a better way of producing food and fiber. They looked at the high-tech agricultural methods of most farmers and saw devastating effects on the environment and human health. Pesticides were one of the main culprits.

“Pesticides, by their very nature, kill things,” says one anti-pesticide lobbying group, Beyond Pesticides. “Besides killing non-target organisms, many of these synthetic pesticides have deleterious effects on long-term species survival because they impair their reproductive abilities. Endocrine disrupting pesticides affect the hormonal balance of wildlife and humans, often at very low doses.”

As early as the 1940s, some farmers and advocates were experimenting with ways to grow crops without synthetic pesticides or fertilizers. By the 80s, consumers were driving more and more farmers into organic practices to meet the growing demand, but there were more than 40 private organizations and state agencies claiming to “certify” certain foods as “organically grown.” Their standards differed, so consumers weren’t getting what they were paying 40 to 200 percent more in retail prices for.

So, in the late 80s, consumer and producers asked Congress to step in. The Organic Foods Production Act of 1990 directed the Secretary of Agriculture to set up a National List of Allowed and Prohibited Substances that can or can not be used if the produce is to be certified “organic.” Today that list is 16 pages long with overarching categories of substances banned or approved.
In general, and as one might expect, organic farming does not allow for the use of any synthetic pesticides or synthetically produced fertilizers. These are the very substances that high-tech, 20th century agriculture has relied on to increase yields.

Yet, organic farmers still need to control weeds and pests – at least to an extent. Dave Vetter is a large organic grower and processor north of Aurora, Nebraska, and he can tolerate a lot more weeds than his neighbors. “A few weeds don’t hurt anything,” Dave says. “Actually, you can have quite a few, and they have very little impact on your crop. We don’t need to have fields with just soybeans or just corn in it… We’re looking at cropping sequence to manage insect pressures at certain stages of crop growth.”

Ironically, there are some synthetic substances that are allowed in organic crop production.

Controlling weeds is the second priority for most farmers after supplying enough nutrients. As Dave Vetter talked about, many organic growers have developed strict crop rotation systems that keep weed populations from establishing themselves from year to year. Other growers have gone back to hand weeding – or “roughing,” as farmers in central Nebraska call it. Others mulch between their crops with newspapers, recycled paper, crop residues or even clear plastic during the hot days of summer. Others use natural pre-emergent herbicides, garlic, clove oil, borax, soaps, pelargonic acid, vinegar or even controlled flame throwers to knock down weeds.

Controlling insects is more difficult, but one solution is to simply ignore much of the damage they might do – plants can generally survive the loss of up to a third of their leaf area before suffering consequences.

To put it another way, some organic consumers agree with the Joni Mitchell lyrics from “Big Yellow Taxi” –

Hey, farmer, farmer put away that DDT, now!
Give me spots on my apples,
But leave me the birds and the bees, please!

But there are naturally occurring insecticides that have been approved for organic farming. The most famous are compounds harvested from the Bt bacterium and from the Chrysanthemum flower.

The Chrysanthemum produces a natural insecticide known as pyrethrum. The compound is effective against a variety of insects and some manufacturers have formulated a synthetic version known as permethrin. Some organic gardeners will plant Chrysanthemum flowers close to crops like broccoli to naturally repel insects like aphids, leafhoppers, spider mites, ticks, pickleworms and cabbage worms.

There are several species of Bt bacteria that manufacture their own insecticides, and these have been used in organic farming for decades. Several Bt species will be naturally toxic to a single species of insect, so these insecticides are highly selective. The bacteria have also supplied genetic engineers with the genes for Bt crop varieties.

Even though there are natural pesticides that are allowed for organic farming, most farmers don’t use them. One study found that less than 10 percent of organic growers used permitted pesticides regularly.

Most organic farmers want to become the next Takao Furuno. Takao is a Japanese rice farmer who spent 20 years weeding his rice paddies by hand. He was getting older and more tired. He came across references to old organic farming techniques of raising ducklings alongside the rice, and he tried it. The results surprised him. The birds ate the weeds and pests he’d worked so hard to eliminate all those years. Their droppings nourished the rice, raising yields. Plus he had the ducks to sell, as well. So he tried other organic techniques like adding fish to the flooded fields.

Mr. Furuno became a hero to the organic agriculture movement when he wrote a book, The Power of Duck. It’s now been translated into several languages, and his techniques have been replicated or adapted around the world.

Written by Bill Ganzel, the Ganzel Group. First published in 2009. A partial bibliography of sources is here.