Hemp Bugs: The Truth About Pests and Pesticides

There’s no denying it, hemp is on a roll across the country. However, reading through various articles about the new miracle crop, I keep coming across a false claim — no, an outright LIE — regarding hemp and pesticides. Over and over I have read something to the effect of:

  • Hemp is resistant to pesticides!


  • Hemp is resistant to pests and therefore needs no pesticides!

And let me be the first to tell you, this is absolute bullcrap. This is false information being spread to consumers. Not only does it come from a place of ignorance and prejudice, but I have concerns that consumers who are anti-pesticide are being exposed to pesticides in their hemp products due to misinformation.

Lets start with what I know, what my experience in the field is, and why you should believe me. I work for an aerial applicator company. I am pro-pesticide when used safely, efficiently, and with education — but I also understand there are people who are not comfortable with pesticides in any form, and thats fine! I also work with organic pesticides for about 1/3 of all my applications and can testify that there are organic products which work well, and in fact I rely on some of them more heavily than synthetic prodcts. You need to understand, I am not pushing an agenda here nor am I biased. Although my personal stance may differ, I respect an individual’s choice to choose organic and naturally grown products. However I also believe that consumers deserve to know what they are buying, applying, and consuming, and this lie that hemp is pesticide free violates this belief of mine and really stirs me up.

Now there is a lot to unpack here, and I want to cover as many sides to it as I can. There are four points which I would like to address from my first-hand experience this past year.

  1. Hemp is susceptible to a wide variety of pests.
  2. Hemp is not “resistant” to pesticides – they work very well on it!
  3. What is legal to put on hemp, and the secretive (and illegal) applications being made to it.
  4. Residual pesticides in the ground.

Hemp is susceptible to a wide variety of pests.

This past growing season, I personally saw a variety of harmful pests actively causing crop damages within hemp fields. These included beet webworms, aphids, thrip, and corn earworm. Now these were only the ones I saw within our valley, and did not include other CONFIRMED pests in hemp elsewhere in the country. I have also heard accounts of stem/stalk borers, mites, and gnats, amongst others.* Of course these pests will vary regionally, but make no mistake: there are confirmed pests in hemp, which are known to cause damage to the product. I suspect that as more and more acres are grown across the country, there will be even more pests emerge within or adapt to hemp fields and green houses. I predict corn earworm, aphids, and mites to be the greatest threats across the board, but time will tell.

Damage to a hemp plant from a beet web worm. This was one of the first pests I confirmed in the crop this year. Note the worm towards the top of the picture.
Aphids on a hemp plant. I did not send these in for lab verification as with the beet web worm, but I believe these to be Cannabis aphids.

Hemp is not “resistant” to pesticides – they work very well on it!

There are three primary classes of pesticides: 1) herbicides to control plants, 2) insecticides/miticides to control insects and arachnids, and 3) fungicides to control various fungi and bacterial diseases. This claim that hemp is resitant to pesticides can go one of two ways.

The first is that hemp is not affected by herbicides, or has a tolerance or resistance to products designed to damage it. Following last year’s planting, there were many people in my area who had issues with volunteer hemp returning from dropped seeds which they needed to eradicate. To do this, they applied herbicides which killed the hemp, thus cleaning out the field for another crop. Because the herbicides eradicated the hemp, one cannot say that hemp is resistant to herbicides.

The second option here is that hemp is resistant to pesticides applied to treat insects, mites, or disease. Because we have already established that hemp does in fact take damage from these insects, you can understand why a grower would apply these products to their hemp field (that is, to control pest populations and mitigate damage to yields and therefore profit). Now, luckily for growers, hemp is NOT resistant to these products either! In fact, I applied a variety of insecticides this past growing season (more on that in a minute), and they worked on the insects they were applied for! I saw reduced populations as well as a reduction in damage to the hemp, indicating that these pesticides worked as intended on the hemp plant.

What is legal to put on hemp, and the secretive (and illegal) applications being made to it.

In my state, there is a relatively short list of pesticides legally approved to apply to hemp crops. Most of these are organic or natural products, and primarily oil-based. Although these essential oils can be incredibly effective, I offer one word of advice to those planning on oiling up their crop to prevent pest: Oils can act as a magnifying glass, eventually burning and killing your hemp plants (aka phytotoxicity). Disclaimer aside, there are next to no products available to treat all the conditions that can afflict this crop. Those that are available work marginally well, but cannot be relied upon for heavy infestations. There are also no herbicides labeled to control the weeds in hemp crops, aside from oil herbicides which, again, work by burning the weeds back.

So instead, what I have observed happening is a massive amount of illegal applications to hemp fields using products not labeled on the crop. Herbicides to combat weeds, insecticides and fungicides to combat pests and disease, and a whole slew of fertilizers which I am certain are not approved for crop use (RAW SEWAGE, anyone?).

The Department of Agriculture in my state is calling this hemp rush the Wild West, in that the number of off-label, illegal applications being made by growers-run-amuck and immeasurable. And if they are already making an illegal application in terms of product, what moral obligation is there to hold true to the approved rates of application? Who is to say these growers aren’t doubling or even tripling the approved rates of product per acre? All I can say on the matter is that illegal and off-label applications are happening, regularly. And if you have concerns about pesticides in your products, I would be certain to buy only from a source who you can confirm isn’t up to these shady self-treatments.

Residual pesticides in the ground.

I’ll only touch briefly on this, because his is more of a labeling strategy than anything. Organic product labeling is overseen by the U.S.D.A, who sets the requirements deciding what is or is not organic. All the information on this can be found in a handy bulletin on the U.S.D.A. website, but the part I want to focus on refers to the ground hemp is grown in.

In order to be certified organic, your organic crop must have been grown in ground for which no pesticides have been used in three or more years. This is because many pesticides (specifically herbicides) can tie up in the ground and persist for a while. Now, I don’t know about your region, but in mine the hemp being grown is primarily going into farm ground…which has previously had pesticides applied to it. This means that very little hemp can truly be labeled “certified organic.” It may have been “organically grown,” which is to say no pesticides were applied to the crop as it grew, but if it is contaminated ground then it cannot be truly organic. Please pay special attention to any “organic” hemp products you may be purchasing, and if in doubt, ask!

* If you’d like me to do another more detailed post regarding pests in hemp and their management options, let me know!

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1 Comment

  1. WOW! That was a lot to take in but I read the whole thing. You made some very interesting points and I hope the right people read it. I am sure similar problems arise with tobacco. Of course, not all “hemp” is used for smoking but used in food and essential oils as well. Thanks for sharing!

    Liked by 1 person

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