Hello Brinda,

Thank you for reaching out to the UVM Extension Master Gardener Helpline with your question about glyphosate residual time and blueberries. Since this is a food safety versus a gardening question, I have reached out colleagues at the Northeast Center to Advance Food Safety. I will get back in touch as soon as I hear back. 

Hi Brinda,

I'm looping back to your question. I checked in with our UVM plant pathologist, Ann Hazelrigg, who also directs the UVM Extension Pesticide Safety Education Program. She indicated that glyphosate is regularly applied to wild blueberry production areas and that the recommended time from application to harvest was a minimum of 14 days, see: https://extension.umaine.edu/blueberries/factsheets/weeds/237-glyphosate-for-weed-control-in-wild-blueberries/

I'm also including information on glyphosate (Round Up) from the National Pesticide Information Center, the EPA and FDA see: 

• http://npic.orst.edu/factsheets/glyphogen.html 
• https://www.epa.gov/ingredients-used-pesticide-products/glyphosate
• https://www.fda.gov/food/pesticides/questions-and-answers-glyphosate

Like any pesticide (designed to kill its target), glyphosate is effective at killing weeds and has the potential to damage your blueberry bushes. Did you happen to notice if there was any damage to your blueberry bushes as a result of the application? That may be an indication that the product had been absorbed into the plants.

I would encourage you to read the resources above. My research suggests that the residual time of this herbicide has now passed as more than 5 half-lives (the "half-life" is the time required for half of the compound to break down in the environment) or 3% or less of the product is assumed to be remaining in the environment at this point (if the product was applied according to the label). The resources above suggest that glyphosate has low toxicity to humans. Personally, I would assume the berries are safe to eat but this is a personal decision that only you can make. I hope the information provided will assist you in your decision-making.