Herbs 'can be natural pesticides'

Common herbs and spices show promise as an environmentally-friendly alternative to conventional pesticides, scientists have told a major US conference.

They have spent a decade researching the insecticidal properties of rosemary, thyme, clove and mint.

They could become a key weapon against insect pests in organic agriculture, the researchers say, as the industry attempts to satisfy demand. The "plant essential oils" have a broad range of action against bugs. Some kill them outright while others repel them.

Details were presented at the Fall Meeting of the American Chemical Society (ACS) in Washington DC.

These new pesticides are generally a mixture of tiny amounts of two to four different herbs diluted in water.

The research was led by Dr Murray Isman, from the University of British Columbia in Vancouver, Canada.

... But the herb-based pesticides also have shortcomings. 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, compared to days or even months for conventional pesticides. As they are also generally less potent than conventional pesticides, they must be applied in higher concentrations to achieve acceptable levels of pest control, Dr Isman said.

Researchers are now seeking ways of making the novel pesticides longer-lasting and more potent, he added.

"They're not a panacea for pest control," Dr Isman explained. ...

via BBC NEWS | Science & Environment | Herbs 'can be natural pesticides'.

Not a new idea, but one worth frequent mention. I believe pesticides are causing more problems that we know.