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Green news from the UC Division of Agriculture and Natural Resources
by RIck Lanman
on June 21, 2021 at 7:12 PM
The 15-page publication omits perhaps the easiest method of organic control of gophers and voles - placement of 2-3 thumb-sized pieces of dry ice into their holes, covering the dry ice with a wad of newspaper, then tamping down dirt on the surface. The dry ice sublimates and because it is heavier than air, stays in their runways. Careful assessment to make sure dry ice is placed in every burrow hole is important. Generally requires repeat application for 3-5 days daily as I always miss a few holes. Have not tried this on ground squirrels who are larger and may require larger blocks of dry ice. I get the dry ice at our local grocery (Safeway).
Reply by Pamela Kan-Rice
on June 22, 2021 at 10:02 AM
Hi Rick, I asked the authors for comment:  
Dry ice can be effective. However, the important detail is that it is not legal to use dry ice in this manner. When you use dry ice to kill rodents, it becomes a pesticide, yet it is not registered for such a use. So, the short answer is that it is not a legal approach for managing most burrowing rodents. I say “most” because there is a very specific label that allows its use against rats in commensal settings. However, to do so, you have to use specific dry ice that is registered for this use, and it is very difficult, if not impossible, to find. Therefore, even in these situations, dry ice really isn’t a practical option.  
The other item to consider would be if it’s even considered an acceptable tool for organic producers (i.e., certified). I doubt it, considering it isn’t even registered as a pesticide.  
Roger A. Baldwin, Ph.D.  
Wildlife Specialist  
UC Davis Department of Wildlife, Fish, and Conservation Biology
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