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Iron Phosphate and Worms #821521

Asked March 02, 2023, 8:29 PM EST

Hello, will iron phosphate, iron phosphate EDTA, or iron phosphate with spinosin kill beneficial garden insects when applied to reduce slug and snail populations?

Lane County Oregon

Expert Response

According to the National Pesticide Information Center (NPIC), studies have shown that beetles and earthworms were unaffected by iron phosphate. You can read more here: http://npic.orst.edu/factsheets/ironphosphategen.html. Spinosad is moderately toxic to earthworms: http://npic.orst.edu/factsheets/spinosadgen.html. Iron phosphate EDTA is the chelated form of the product and studies have shown that iron phosphate with EDTA is toxic to earthworms (and dogs and cats). Here is a good article on the concerns with the EDTA baits from Dr. Linda Chalker-Scott (Washington State University): https://gardenprofessors.com/upon-further-reviewiron-phosphate-for-slugs-and-snails/. The bait with just iron phosphate as the active ingredient is the least toxic. If you prefer a non-chemical approach to slug control, try board traps or one of the other non-chemical approaches listed here: https://catalog.extension.oregonstate.edu/em9155/html.

Erica Chernoh Assistant Professor of Practice Community and Commercial Horticulture OSU Extension Lane County Replied March 03, 2023, 2:17 PM EST

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