You can contact other manufacturers of the various materials on Cornell's list, but I suspect the shelf life of all the materials listed is much more than suggested by Cornell. I never trust their dispatches to home growers- I need to see the source of the research to take things very seriously.

Here's the response from the Gowan rep. I told him about the Cornell claim. He probably believes I'm a commercial grower so I doubt he'd risk the lawsuit potential of misinformation (e-mails don't disappear the way a phone call does). It would be really bad business even without that threat.

Hello Alan,

Thank you for your inquiry concerning the shelf life of Imidan. Your unopened bag of Imidan will be effective for many years. It is true that after 3 years, as with most pesticides, the percentage of phosmet (active ingredient in Imidan) begins to slowly decrease. Though measurable in a lab, it is unlikely that you will notice any difference in field usage for years.

What you may see is a deterioration of the WSB (water soluble bag) in which the Imidan is packed. You could see one or more of the following issues:

- Cracking of the film

- Solubility and/or dispersion of the film

Regards,

Rod Kitterman