Has there been any events of warfare in the past which used invasive plants to damage any country's (or kingdom's) food crops or its natural vegetation?

Some details:

  1. The damage done by invasive species on a small scale is probably known to all. For example: Water hyacinth has an adverse affect on aquatic life. Many more examples could be there. For instance,

    Globally, 1.4 trillion dollars are spent every year in managing and controlling invasive species

    Invasive Species - Wikipedia

  2. I was asked in comment regarding the timeline that I specifically wish to receive in answer when such an warfare (or let's say in simple terms harming another group) happened through the use of invasive plants. As I mentioned before, any event that is mentioned in History books is what I am looking for.

  3. Initially, this question had a link of a recent news article and some updates from comments which have been removed after edit suggestions.

  • 3
    As @gktscrk says, pls expand on the "warfare" term, kind of damage, time frame. Hard data that can be addressed in an answer without speculation and without having people watch questionable news items or read fantasy figures. Analyses, actual threat (bacteria carried, spaceweed of destruction ;-)), and why someone would use such a fox-news friendly distribution method. The trivial answer "no" because it makes no sense. Invasive plants are everywhere. Voting to close.
    – user43870
    Commented Jul 29, 2020 at 13:07
  • 6
    This question is amazing. It's absolutely barmy, but just realistic enough to be thought provoking - more ridiculous weapons of war have been considered, such as gigantic orbiting sun mirrors to fry the earth, and mind controlled squid. If no answer here, try gardening stack.
    – Ne Mo
    Commented Jul 29, 2020 at 15:31
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    The fundamental problem with "invasive plant warfare" would seem to be knowing ahead of time whether a given plant is going to be invasive. E.g. I have garden full of ornamental plants, most of which are not native to my area. None are invasive: some need a good deal of pampering to survive.
    – jamesqf
    Commented Jul 29, 2020 at 17:51
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    Came here expecting a comment or answer about kudzu but was disappointed.
    – shoover
    Commented Jul 29, 2020 at 21:24
  • 6
    I think it may be worth removing the Fox News article from your question, or at least de-emphasising it, because its presence appears to have become a major distraction. I'd personally remove the entire "updates from comments" section, as they mostly address the link and not your actual question, and roll back to the very first revision.
    – F1Krazy
    Commented Jul 30, 2020 at 14:44

3 Answers 3


Another parable put he forth unto them, saying, The kingdom of heaven is likened unto a man which sowed good seed in his field:

But while men slept, his enemy came and sowed tares among the wheat, and went his way.

But when the blade was sprung up, and brought forth fruit, then appeared the tares also.

So the servants of the householder came and said unto him, Sir, didst not thou sow good seed in thy field? from whence then hath it tares?

He said unto them, An enemy hath done this. The servants said unto him, Wilt thou then that we go and gather them up?

But he said, Nay; lest while ye gather up the tares, ye root up also the wheat with them.

Let both grow together until the harvest: and in the time of harvest I will say to the reapers, Gather ye together first the tares, and bind them in bundles to burn them: but gather the wheat into my barn.

Matthew 13:24-30, King James Bible

Obviously this is just a biblical parable, not history, and whatever plant is meant under tares, it was probably native in Iudea, not "invasive". Also it is not speaking about warfare between states, but enmity between individual households.

Nevertheless, this shows that the idea of ruining the enemies crops using plants as biological weapons existed in the ancient world.

  • 4
    nice! and appreciate that you point out it likely wouldn't have been truly invasive. Commented Jul 29, 2020 at 18:14
  • 19
    Excellent counterexample to the chronocentric worldview. Our predecessors may not have had the technology to actually execute such warfare, but we're fools if we think they were stupid and couldn't imagine it. Commented Jul 29, 2020 at 19:11
  • 18
    "Tare" is a genus of tufted grass, also known as Lolium - many species of this genus appear virtually identical to wheat until almost fully grown (collectively referred to as "darnel"), making them extremely difficult to separate from the wheat before harvest - while others look nothing like wheat, and would be easy to distinguish even while young Commented Jul 30, 2020 at 7:58
  • I've heard before that tares are deadly to eat, although the person speaking didn't mention the ones that look differently from wheat. That said, the point they made was that the farmer essentially had lethal poison sown in with - and deliberately disguised as - an edible crop; and according to them, this referred to either false teachings or false teachers that lead people astray, in a serious enough way that it leads to death. Commented Jul 31, 2020 at 14:14
  • Of course, it's possible that even if that's so, that there may be a few other, distinct dynamics the parable was originally designed to point to as well (such as wolves in sheep's clothing hiding among the genuine, which is a broader category overall). Commented Jul 31, 2020 at 14:20

Invasive species (not just plants) theory, and the biological knowledge to use it offensively, is relatively new. And, even if attempted, the granting of beneficial outcomes (to the attacker) would lag the initial issue by years, while providing a casus belli from the start if caught. If the situation did not necessarily develop to the attacker's advantage, i.e. if they lost, they'd be stuck paying reparations for decades as they'd have no easy way to "turn off" their attack vector.

Not to mention that, in a number of instances, invasive species were originally intentionally introduced to improve the local situation. So, if miscalculations are common, the reverse (an unintentional benefit to the attacked party) - or at the very least a relative lack of negative effects - could be somewhat expected.

to steal a point from B. Lorentz excellent answer: in the past most enemies were right next to each other, sharing the same ecosystem or with adjacent ecosystems, so the scope for novel invasive species would have been limited.

Last, but not least, historically a good proportion of wars were prosecuted to annex territory. So seeding ecological disruption in what's hopefully soon to be your territory is an additional disincentive.

So a) never heard of that, b) historically not something countries would have thought to try (unlike say flinging plague-ridden corpses into besieged cities) and c) there are many good reasons a country would think twice before using it, unless they were ready to commit to a deeply adversarial relationship for the long haul with limited immediate short term benefits.

re. the article:

But, what’s actually inside seem to be random plant seeds.

Darn sloppy weapon production quality assurance ;-)

Edit: None of this answer is written from the viewpoint that there is ecological warfare going on in the originally linked news story or that the OP believed there was. It's just looking at the practical limitations accounting for the likely lack of historical use.

  • 2
    The theory of using it as warfare as a scientific theory might be new, but it has been done by accident for decades, if not centuries. While never done intensively like asked by OP, there are examples where meddling with the crops of enemy nations was done in way way or another. I think one of the reasons it hasn't been done on large-scale (yet) is because usually you have war with your neighbour, not someone at the other side of the globe. Fighting wars globally is something relatively recent (yet predates WW I), simply because we didn't have the means to economically do so.
    – Mast
    Commented Jul 30, 2020 at 7:00
  • 1
    I would doubt the casus belli. There is a huge chance for plausible deniability. It was a small company who just wanted to defraud customers, or it was terrorists, or seomthing like this.
    – vsz
    Commented Jul 30, 2020 at 14:08
  • @vsz right. Heck, even “ 'twas the wind and nothing more! ” Commented Jul 30, 2020 at 15:51
  • @Mast "meddling with your enemy's crops" was indeed pretty common. By 🔥-ing them. If you are using local pests however, rather than truly novel invasive species (like the Bible quote above) you'd need to put in some manual efforts to do it - they wouldn't be self-propagating or else they would have already be colonizing your target's cropland. That's the beauty of non-local invasives - if they can multiply and have left their usual predators behind, they could go viral without much need of your help (and much more deniable than having your folk skulking around on enemy territory). Commented Jul 31, 2020 at 17:51

If you're willing to forego the 'warfare' aspect, which given the nature might be difficult to prove, Wikipedia has a list of invasive species, which includes plants.

Assuming the question was inspired by the recent reports of mysterious Chinese seeds arriving in the US and the UK, there's a list of pre-existing invasive species for the UK and for the US. This includes such externally introduced species like Japanese knotweed, Kudzu and Himalayan honeysuckle, which are species found in China.

A number of key features invasive species tend to include are:

  • Outcompeting native species
  • Growing at a much faster rate due to lack of predator species
  • Being difficult or time-consuming to remove
  • Containing a noxious or toxic substance, which may also be harmful to humans
  • Destroying beneficial species, either by outgrowing or outcompeting them
  • Ruining an ecological environment to the point it can no longer recover
  • Property damage (E.G. undermining foundational structures)

As other posters have noted, it would take quite a few years to come into effect, however this ignores the possibility that some weaponised plant species may be genetically modified to demonstrate other possible traits.

Plants that have been genetically modified are capable of producing their own pesticides, it wouldn't take much to imagine a modified species that produces something potentially more toxic, that, instead of being geared to insects, is geared towards attacking humans, perhaps, for example, producing neurotoxins in normally edible species, contaminating the food supply.

Historically there doesn't appear to be any ecological warfare to note, but given there have been attempts to weaponise animals (bat bombs, pigeon bombs, remote control dogs), bacteria and viruses, it would be hard not to imagine an attempt to weaponise plants.

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