Purdue University scientists are questioning recent statements by groups opposed to the use of genetically modified (GM) crops, specifically that glyphosate use and Roundup Ready technology are impacting the health of plants, animals and possibly humans.

In an article published Thursday, the scientists wrote, “… evidence to support these claims has neither been presented to nor evaluated by the scientific community.”

The article is authored by Purdue’s Jim Camberato, Extension Service Soil Fertility Specialist; Shaun Casteel, Extension Soybean Agronomist; Peter Goldsbrough, head of the Botany and Plant Pathology Department; Bill Johnson, Extension Weed Scientist; Kiersten Wise, Extension Field Crop Pathologist; and Charles Woloshuk, Extension Corn/Mycotoxin Pathologist.

Not mentioned in the scientists’ critique is retired Purdue professor Don Huber, who allowed GMO opponents to release a letter he sent to the U.S. Department of Agriculture, warning of what he claimed was a newly discovered pathogen linked to glyphosate, the active ingredient in the herbicide Roundup. Huber called for an emergency investigation, and for USDA to stop deregulating Roundup Ready crops.

But the Purdue article challenges some of the claims that Huber, a longtime critic of biotech crops, made in his letter, particularly his assertions about plant disease and decreased crop yields. Some of the same scientists have disagreed with Huber before. Last year, following an article based on an interview with Huber, they wrote, “In our opinion the doomsday scenario painted by this article is greatly exaggerated.”

Some of the Purdue scientists’ latest key points:

Although herbicides, such as glyphosate, have the potential to increase disease in certain plants, plant pathologists have not observed a widespread increase in susceptibility to plant diseases in glyphosate-resistant corn and soybean.

The claim that plant disease has “skyrocketed’ due to glyphosate use is unfounded.

Very few pathogens infect both plants and animals, and while fungi in the genus Fusarium can produce mycotoxins that can be harmful to animals and humans, the majority of Fusarium fungi are pathogens of corn and wheat. Wheat and food-grade corn are non-GMO crops, meaning that mycotoxin development in these crops would not be directly linked to glyphosate use or interactions.

Overall, claims that glyphosate is having a widespread effect on plant health are largely unsubstantiated.

The authors conclude by reaffirming their recommendation of judicious glyphosate use for weed control, adding,  “We encourage crop producers, agribusiness personal, and the general public to speak with University Extension personnel before making changes in crop production practices that are based on sensationalist claims instead of facts.”