McNeill says that in the Midwest and other areas of the country, such as Louisiana and Mississippi, weeds like water hemp, giant ragweed, lamb’s quarter and velvet weed have become Roundup resistant through natural selection, due to a particular genetic mutation that survived the poison and therefore reproduced successfully and wildly.

The problem is, farmers’ natural reaction has been to simply apply more Roundup to their crops, which is having deleterious impacts, McNeill says.

“Used judiciously, it can be a useful product, but as with anything, if you abuse it, it can have negative effects,” he says.

McNeill explains that glyphosate is a chelating agent, which means it clamps onto molecules that are valuable to a plant, like iron, calcium, manganese and zinc.

“When you spray glyphosate on a plant, it’s like giving it AIDS,” he says.