Organic Does Not Mean "Pesticide-Free". It is a common misperception that organic farming is pesticide-free. When, in fact, organic farmers are allowed to use a number of toxic pesticides. While organic farmers promote non-chemical pest control measures, such as crop rotation and beneficial insects, they still use chemical pesticides when pests threaten their crops. This fact is especially noteworthy since most organic farmers receive a premium for their organically grown produce.

The fundamental difference between organic and synthetic pesticides is not their toxicity, but their origin, that is, whether they are extracted from natural plant, insects, or mineral ores or are chemically synthesized. Frequently, some organic pesticides such as commonly used nicotine have mammalian tonicities that are far higher than some synthetic pesticides. Nicotine, for example, has a rat LD50 of 55 mg/kg as compared to the newest synthetic insecticide, imidacloprid that has a rat LD50 of 425 mg/kg. This makes nicotine 10 times more toxic than the newest synthetic insecticide.

The toxin from Bt (Bacillus thuringiensis) is the most used pesticide on organic farms while over all oil, sulfur, and copper combined accounted for 25% of U. S. pesticide use including organic and non-organic farming (1997). A number of additional organic pesticides, including botanical extracts such as pyrethrum, neem, sabadilla, and rotenone are used. According to Alex Avery, government authorities have no statistics at all on the use of any organic pesticides other than oil, sulfur Bt and copper even though millions of pounds are used every year. Avery contends that this is "somewhat puzzling because many organic pesticides are used more intensively than non-organic pesticides. This is due to the lower effectiveness of organic pesticides compared to there synthetic counterparts."

Two organic-approved pesticides alone account for 23% of all U.S. agricultural pesticide use in 1997, with oil accounting for 56% of all 'insecticides' and sulfur accounting for 59% of all 'fungicides'.

Sulfur and copper are the two heaviest used fungicides and are applied at significantly higher rates of active ingredient than synthetic fungicides. Nearly 78 million pounds of sulfur was used on 2.2 million acres, an average of 34 pounds per acre. Copper was used to treat 3.3 million acres with 13.7 million pounds or over 4 pounds per acre. These uses are contrasted with 40 million pounds of synthetic fungicides applied to 25 million acres or only 1.58 pounds per acre (1997 data).

What if the U.S. shifted to 100% organic? Because of the lack of statistics, it is impossible to accurately estimate the increase in the use of organic pesticides under an all-organic scenario. Avery provided several plausible paradigms under which pesticide use would skyrocket. Since the use of Bt as a replacement for synthetic insecticides is limited by a very narrow range of crop pests, millions of pound of oil or other organic insecticides, such as pyrethrum, neem, rotenone, or sabadilla, would need to be used. Oil is currently used at an average rate of 49 pounds per acre as compared to 1-4 pounds per acre for a typical synthetic insecticide. Newer synthetic insecticides, such as imidacloprid, have average per acre use rates of less than 0.5 pounds per acre. Because organic insecticides are less effective and degrade more rapidly than their synthetic counterparts, organic insecticides also would need to be used more frequently to achieve the same level of control. The increase in fungicide use that could be expected with a conversion to all organic can be estimated by replacing synthetic fungicides with copper or sulfur. In 1997, sulfur was applied at an average rate of 34.8 lbs. per acre-a rate 22 times higher than the average synthetic fungicide rate or 1.58 lbs. Thus a replacement of all synthetic fungicides with sulfur would require an additional 840 million lbs. (a 738% increase). Copper was applied at an average rate of 4.08 lbs. per acre in 1997, which is 2.5 times higher than the average synthetic fungicide rate. Replacement of synthetics with copper would require a 47% increase in overall fungicide use. Use of copper would than total 116 million pounds as compared with 40 million pounds of synthetic fungicides now used. These examples serve to illustrate the greater use intensity needed for organic pesticides. Furthermore, sulfur and copper are far more persistent in the environment than their synthetic counterparts.

Weeds are the oldest and most persistent problem in agriculture. Herbicides are the least toxic class of pesticides and offer most environmental benefit. Typically herbicides narrowly target plant enzymes and are virtually harmless to insects and mammals. The proven benefits, including less tillage and erosion, are enormous. An all-organic mandate would eliminate all these benefits.

Conclusion

Factual evidence as presented in Alex Avery's recent paper, and outlined in this column, suggests that a major shift to organic agriculture would mean more pesticide use, not less; more toxicity, not less: and higher pressure on natural resources without commensurate offsetting benefits.