August 18, 2009
Natural Pesticides Found In Herbs
An environmentally friendly alternative to pesticides can be found as close as your herb garden, according to scientists who have spent a decade researching the matter.
Researchers decoded the insecticidal properties of rosemary, thyme, clove and mint.
The herbs could become a key weapon against insect pests in organic agriculture as the industry tries to satisfy demand.
The "plant essential oils" have a broad range of action against bugs: some kill them right away and others repel them.
On average, two to four different herbs were diluted in water, according to Dr Murray Isman, from the University of British Columbia in Vancouver, Canada.
Dr. Isman said, "These products expand the limited arsenal of organic growers to combat pests," he said.
"They're still only a small piece of the insecticide market, but they're growing and gaining momentum."
Unlike conventional pesticides, these spices offer an additional advantage. Insects are less likely to evolve resistance, Isman says.
The spices are also safer for farm workers, who are at high risk for pesticide exposure.
Herb-based pesticides are far from perfect. Since the essential oils made from these herbs tend to evaporate quickly and degrade rapidly in sunlight, farmers need to apply them to crops more frequently than conventional pesticides.
Some last only a few hours so they must be applied in higher concentrations to achieve acceptable levels of pest control, Dr Isman said.
Researchers are trying to find ways of making the novel pesticides longer-lasting and more potent, he added.
Dr. Isman says, "It comes down to what's good for the environment and what's good for human health."
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