The Q&A Archives: Diazinon

Question: After moving into this house I realized my garden space (1500 sq ft ) was over run with earwigs. So, I rototilled probaly twice as much Diazinon as I needed in to my soil. That was about 5 years ago. Shortly after I did this I started gardening organically. However, I recently read that this type of poison can stay in your system for as much as 10 years. Is this true, or has the diazinon dissapated from my soil by now?

Answer: Diazinon has a low persistence in soil. The half-life is 2 to 4 weeks. Bacterial enzymes can speed the breakdown of diazinon and have been used in treating emergency situations such as spills. Diazinon seldom migrates below the top half inch in soil, but in some instances it may contaminate groundwater.

In plants, a low temperature and a high oil content tend to increase the persistence of diazinon. Generally the half-life is rapid in leafy vegetables, forage crops and grass. The range is from 2 to 14 days. In treated rice plants only 10% of the residue was present after 9 days. Diazinon is absorbed by plant roots when applied to the soil and translocated to other parts of the plant.

For a complete description of diazinon, and all the facts associated with its effects and persistence in the soil, visit this website:

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