Misconception Number 7: Organic farming uses pesticides that damage the environment: natural pesticides are more dangerous than conventional pesticides because they are less efficient and therefore require the application of huge quantities. This is also true for fungicide (e.g., organic grape producers contaminate the soils with large quantities of copper because they are not allowed to use modern fungicides). In addition, some organic pesticides are as poisonous as synthetic ones (e.g., nicotine and pyrethrum).
Summary of Counter-Arguments:
Details of Counter-Arguments:
As explained in the answer to misconception number 43, natural molecules (such as those present in natural pesticides) can be very toxic for certain species (e.g., they are used as natural pesticides to kill certain insects), but are not toxic for the environment as a whole because other species can digest them without problem and they do not accumulate in the environment or food chain.
Pure nicotine is not allowed in Organic Agriculture. Nicotine found in tobacco tea is also forbidden in some organic standards.However, tobacco tea is permitted under other organic standards because it is a plant extract produced on-farm and the concentration of nicotine in tobacco tea is typically low, meaning only minute quantities of nicotine are actually applied. In addition, this nicotine breaks down very rapidly in the environment. The use of tobacco tea or other home-brewed pesticides allows the farmer to be less dependent on manufacturers and traders of pesticides, which is particularly important in third world countries. Moreover, the toxicity of tobacco tea is considerably lower than the one of nicotine sulphate (the product that is commercialized). Nicotine sulfate is manufactured by combining nicotine from natural tobacco waste with sulfur, resulting in a very toxic and dangerous substance. Homemade tobacco teas do not result in this same toxic substance. While the acute toxicity of nicotine (present in tobacco tea) is still quite high and hence hazardous for the person that comes into direct contact with the spray, the residual period, on the contrary, is short. This means that the farmer has to protect himself well when using the product, but that the product is not hazardous for the consumer. Nevertheless, many organic regulations forbid the use of certain natural pesticides (on-farm produced plant extracts) when their toxicity is controversial. Hence, pure nicotine, as well as nicotine naturally present in tobacco tea, is forbidden by organic regulations of major organic markets, including those of the US, the EU, and Japan.
Pyrethrins are natural insecticides produced by certain species of the chrysanthemum plant. Pyrethrins are one of the least poisonous insecticides to mammals because they are quickly broken down into inactive forms and pass from the body in urine and feces.  The main environmental problem with pyrethrins is their toxicity to aquatic life, but the likelihood of them reaching and persisting in water bodies is low because they have an extremely low pesticide movement rating since they bind tightly to the soil and they rapidly degrade in sunlight at the soil surface and in water. Hence pyrethrum, like other natural pesticides, appears much less toxic than most synthetic pesticides.
Mineral inputs used in Organic Agriculture should contain as few heavy metals as possible. Due to the lack of any alternative, and long-standing, traditional use in Organic Agriculture, copper and copper salts are exceptions for the time being. However, the organic sector is aware of the risk of dependence on copper for pest management and control. Research is underway to find acceptable biological alternatives and disease management strategies to replace the use of copper in the long run. More research is needed, but already some promising alternatives have emerged, such as potassium bicarbonate, which occurs in nature and is an effective fungicide that is safe for humans and the environment. Research has also shown that milk by-products and milk waste can be very effective in controlling moulds and fungi. Other research is being done on how to bring in beneficial micro-organisms that will attack fungal diseases. In the meantime, many certifiers put restrictions on the use of copper salts (often limited to 3kg/ha per year on a rolling average basis) and/or require that, if farmers are using copper, they are required to conduct soil tests to make sure there is no copper toxicity.
In any case, Organic Agriculture relies first on preventive measures and only as a last resort on natural pesticides to control pests and diseases in crop production. If there is a pest outbreak despite these preventive measures, organic farmers typically use natural pesticides wisely, so as to disturb natural equilibrium as little as possible.
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