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Andrew Kniss

Associate Professor of Weed Ecology & Management, Department of Plant Sciences at the University of Wyoming

Expert Bio

Andrew Kniss is an Associate Professor of Weed Ecology & Management in the Department of Plant Sciences at the University of Wyoming. He has a PhD in Agronomy with a minor in Statistics. Andrew's research program focuses on developing weed management programs in agronomic crops, especially sugarbeet, winter wheat, corn, and dry edible beans.

He has authored or co-authored 20 peer-reviewed journal articles and 1 book chapter. He teaches undergraduate and graduate level courses including Ecology of Plant Protection, Weed Science & Technology, and Applied Dose Response Analysis. He recently received the Outstanding Weed Scientist – Early Career award from the Western Society of Weed Science, and serves on the Board of Directors of the Weed Science Society of America. He grew up on a small farm in Nebraska. His interest in weeds began early in life after being forced against his will to pull nightshade berries out of dry bean windrows prior to harvest (he now thanks his dad for that experience).

Studies, Articles and Answers

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Q: How does the GMO-friendly scientific community respond to the potential connection between increased Glyphosate use and Autism prevalence? (Don't use the tired NT response that the DSM is more inclusive - if the current rate of Autism, 1 in 88, existed d

Answered By Andrew Kniss - Aug 19, 2013

A: There is simply no reason to believe that there is any link between increased use of glyphosate and increased prevalence of Autism Spectrum Disorder (ASD). Certainly, glyphosate use has increased due to widespread use of glyphosate-resistant crops. And there also appears to be an increase in the prevalence in ASD over the same time period. But just because two things happen at the same time, does not mean there is a causal relationship (or any relationship, for that matter). For example, between 1997 and 2007, deaths from cardiovascular disease declined 28 percent; but there is no reason [...]

Environment How GMOs Are Made Modern Agriculture


Q: Gmo manufacturers claim their products will lower the use of pesticides. However, pesticide use is increasing due to bt resistance from pests and increasing populations of non-targeted pests. How do manufacturers of GMOs plan to combat the increased cos

Answered By Andrew Kniss - Aug 20, 2013

A: Planting of Bt crops has significantly lowered the use of insecticides in cotton and corn. After over a decade of widespread Bt crop use, it is not too surprising that some insect pest populations are now evolving resistance to this trait. Consequently, farmers may be using insecticides to combat these Bt-resistant pests. It is important to note, though, that Bt-resistant insects are not the only reason for using an insecticide in addition to Bt corn hybrids; some farmers use the two tools in combination to manage secondary insect pests and also to try to prevent resistance from evolving. Whi [...]

GMOs & Farmers Pesticides


Q: How can adding a lot of toxic poison (pesticides) to the ground be good?

Answered By Andrew Kniss - Sep 13, 2013

A: To really address this question, it is important to put “toxic poison” into perspective. It is true that pesticides are, by definition, toxic. But toxicity is relative; recall the old adage that the dose makes the poison. What may be a “toxic poison” to one species may actually be quite safe, and even a food source, to another. For example, chocolate is a toxic poison to dogs, but a nice treat to us. Pesticides should be considered in a similar context. Even though a pesticide is a toxic poison to the target pest (be it a weed, insect, or plant pathogen), the toxicity of most pesticides is qu [...]

Environment GMOs & Farmers Health & Safety


Q: How many days the glyphosate still active in the soil

Answered By Andrew Kniss - Oct 02, 2013

A: The soil half-life of glyphosate is approximately 47 days (with a range of 2 to nearly 200 days depending on soil type and various environmental conditions). But it is not active for a vast majority of that time. In order for glyphosate to be active as a herbicide, it must first (obviously) enter the plant. But glyphosate binds very tightly to soil particles almost immediately upon reaching the soil, and pesticides are not absorbed by plants while they are bound to the soil. Glyphosate is degraded relatively quickly by soil microorganisms, so there is almost never enough available glyphosate [...]

Environment Pesticides