weeds — hemp dogbane

Let us speak for a moment of hemp dogbane.  hemp dogbane

Do a search for it online.  “Hemp dogbane:  Apocynum canabinum.”  The United States Department of Agriculture’s Agricultural Research Service  —  “Normally, animals avoid hemp dogbane because of its bitter, sticky, milk-white juice. Sheep are more frequently affected than other animals, as they will eat large quantities of hemp dogbane leaves and tops . . .” and “Death from poisoning generally occurs 6 to 12 hours after animals eat the plant. Both dried and green plants are toxic. A lethal dose for most animals is reported to be about 0.5 gm/kg body weight, but as little as 15 gm of green leaves have been reported to cause death of some cows. ”  Or the Virginia Cooperative Extension,   which informs us “this weed may be poisonous ether green or dry, and only 15-30 grams of green leaves are required to kill one horse or cow.”  Further investigation will turn up many other similar reports, all sufficiently similar to seem to indicate a single parent source.

Now, let’s look at a Penn State bulletin from 2016 (thank you, Penn State!), also treating of Aponcynum canabinum, commonly known as hemp dogbane:  “Much of the literature on hemp dogbane claims that it is poisonous to livestock, but these claims were based on an early investigation in which oleander (Nerium oleander) was mistaken for hemp dogbane.”  (As little as a single leaf of oleander can kill an adult human.)  It also adds, “Animals find fresh hemp dogbane distasteful, but can eat it in hay without suffering ill effects.”

Now, we’ll go ask the cows, who eat it first and voraciously when they are turned into a new paddock.  Distasteful?  It’s a favorite forage.  Ill effects?  None.

What is the agribusiness industry recommending?  Well, the USDA says it “may be controlled by repeated treatment of 2,4-D (italics ours)” while the Vermont extension suggests killing it with Accent, Beacon, Banvel, or Roundup Ultra herbicides, alone or in combination.  Poison the poison, in other words.  Only, it seems this particular plant isn’t poisonous after all.  We are to douse the fields with toxic chemicals, without even knowing the enemy.

And this is science, people, the god we’re never supposed to question.



3 thoughts on “weeds — hemp dogbane

  1. It makes you wonder who funds the science sometimes.
    I did a quick search on DEFRA the UK advisory body and it doesn’t get a mention, but then after worrying in the past about various plants I now tend to let the animals decide, unless it is going into the hay they seem to know best.

  2. yes, and unless it’s more than just a trace; if we were to try to eliminate all the toxic plants in the pasture — even just all the ones we know — it’d be a labor of Hercules, impossible for mortals, and pointless at any rate. I can think of four off-hand that are ubiquitous and abundant —

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