http://www.badlandsjournal.com/2011-04-03/007640Mainly, his claim of an unknown organism associated with the use of Round-Up Ready soybeans:
"This previously unknown organism is only visible under an electron microscope (36,000X), with an approximate size range equal to a medium size virus. It is able to reproduce and appears to be a micro-fungal-like organism. If so, it would be the first such micro-fungus ever identified. There is strong evidence that this infectious agent promotes diseases of both plants and mammals, which is very rare."
A virus-sized fungus that infects both plants and animals is completely unheard of. If confirmed, he could be eligible for the Nobel Prize. So far, I've read nothing about this finding being reported in any reputable, peer-reviewed journals. Without independent confirmation of his find by separate labs and critical peer review, it is very hard to take him seriously.