Research says that you need to rethink your options if you believe that organic pesticides are 'greener' than conventional pesticides.
A new University of Guelph study reveals some organic pesticides can have a higher environmental impact than conventional pesticides because the organic product may require larger doses.
"The consumer demand for organic products is increasing partly because of a concern for the environment. But it's too simplistic to say that because it's organic it's better for the environment. Organic growers are permitted to use pesticides that are of natural origin and in some cases these organic pesticides can have higher environmental impacts than synthetic pesticides often because they have to be used in large doses," said environmental sciences professor Rebecca Hallett.
Hallett and PhD candidate Christine Bahlai examined four synthetic pesticides: two conventional products commonly used by soybean farmers and two new, reduced-risk pesticides. They also examined a mineral oil-based organic pesticide that smothers aphids and another product containing a fungus that infects and kills insects.
"We found the mineral oil organic pesticide had the most impact on the environment because it works by smothering the aphids and therefore requires large amounts to be applied to the plants," said Hallett.
The mineral oil-based and fungal products were less effective, and also killed ladybugs and flower bugs, which naturally protect the crop, reducing the amount of pesticides that are needed.
"Ultimately, the organic products were much less effective than the novel and conventional pesticides at killing the aphids and they have a potentially higher environmental impact," she said.
The study is published today in the journal PloS One.