AUTHOR: David Petit
DATE: 01/09/23
This is a very controversial question because there is no simple answer. We as Master Gardeners disseminate scientifically defensible information approved by the University of California. Beyond the science we ask you to review the information that we provide and decide on what action to take based upon your own assessment of that information and any follow up studies that you perform.
As Master Gardeners, we advise the public to always employ a technique called Integrated Pest Management or IPM for short. The first step of IPM is to identify the problem and decide whether control measures are warranted. The use of Roundup near edible crops is sometimes a warranted control measure but only when used as directed on the label and taking care to only use it as needed for the specific pest problem.
Roundup has an active ingredient called Glyphosate that has been studied extensively to evaluate whether its use is safe. Glyphosate is effective at controlling a wide range of annual and perennial grassy and broadleaf plants. Here is a link to a document that UC-IPM provides called Addressing the Science Surrounding Glyphosate. This article provides guidance on the risks and toxicity of Glyphosate and is a good starting point to assess the risks of using Roundup near your citrus trees. Based on that article, there are clearly potential health risks associated with consumption of food grown where Roundup was applied.
If you generally eat only organic food that is pesticide free, then you probably won't want to eat any of the fruit from these citrus trees for a period of time. How long you ask. The path to degradation of Glyphosate can be affected by many factors including soil make up and the micro-organisms present in the soil which can break down the Glyphosate. Here is a link to one study that will give you an idea of the complexities involved and estimates of degradation time involved.
There is another factor to consider when assessing whether to avoid eating foods that may have been contaminated by Roundup. We have so far focused on Glyphosate which is advertised as the active ingredient in Roundup. But there are also "inert" ingredients to consider. One scientific study found that "Roundup's inert ingredients amplified the toxic effect on human cells-even at concentrations much more diluted than those used on farms and lawns. One specific inert ingredient, polyethoxylated tallow amine, or POEA, was more deadly to human embryonic, placental and umbilical cord cells than the herbicide itself." So, all the more reason to be cautious with foods that may be contaminated by Roundup.
Beyond the science, you will find much controversy. The Florida Citrus growers will declare their juice to be safe. While the Mom's Across America will provide evidence that that same orange juice is contaminated. I recommend that you ignore the controversy and make your decision to harvest and consume the food that may be contaminated with Roundup based on your assessment of the risks outlined using scientific studies as a starting point.