A REALLY Sensitive Site

Sunday July 8, 2012


Mr Pest Control


I have been asked to recommend or spray for pests on medical marijuana plants. I know people will be inhaling this by smoking the leaves. Is there a product or products that can be used without harm to the users?

Jim, NM

Mr Pest Control


Well, I suppose I should have known this one was coming someday and been prepared with a snappy response. Personally, I think you absolutely should avoid any involvement here, but for some good reasons. If you do need to back out of it diplomatically you can offer that you are only permitted to use products that are labeled for the site, and I don't know that I have ever seen "cannabis" on any insecticide labels. Perhaps there are some products out there, but it would be unusual. We can't even lump this in with general labeling for use on "ornamental" plants, since this plant is being used for a specific purpose. This may be something you could discuss with your local agricultural folks to see if they can suggest a product that would be effective and legal. 

But, one or two things to keep in mind that have to do with your liability. Assuming this truly is "medical" marijuana being grown and sold legally, it will be used by people whose health may already be compromised in some way. Now, a "pesticide" has been added to the mix and any additional health consequences the users experience could point the finger at you, whether or not what you used had anything to do with it. You definitely would not want to use any material that has any residual to it, but only a short-lived contact active ingredient that could be capable of killing the targeted pest and then either removed by washing with water or degraded by itself. 

It also would be important to know what pest problems they are having, as some of these may be resolved without insecticides. Aphids, for example, can often be physically washed off a plant with a spray of water, and reinfestation takes awhile for them to accomplish. 

Now, a quick look does show the internet to be FULL of information on how to control various pest problems on marijuana, but I accept that the internet is not always going to present information that is legal or responsible, so if you choose to browse it do so with a critical mind. Recommendations for insect control center around "natural" plant-derived insecticides as well as insecticidal soap, but again this still could open you up for some liability if someone believes they were harmed by inhaling residues of even these natural materials. After all, we know very well that "natural" does not mean "safe" or "non-toxic", and in fact many natural chemicals sit high on our lists of the most toxic substances (strychnine, nicotine). In fact, I am slightly amused by the recommendation on one site to use tobacco juice to control mites on marijuana. This seems to be the use of a known carcinogen on a product that later will be inhaled by users. 

Mr. Pest Control

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Please note, Mr. Pest Control is answering questions supplied by PMP customers across North America. His answers are generated from industry and manufacturer-provided information. The answer may not be specific to the laws and regulations for your State, Province, Territory or Country. In addition, products mentioned may not be registered and or available in all areas. Always check with your local Univar office for specific information to your area. Always read and follow label directions.