Garlic Mustard—Exposing a Trail of Lies, Hearsay, and
Ignorance
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| Garlic Mustard is claimed to be allelopathic, meaning that it makes the soil inhospitable for native plants to grow nearby. This claim is undoubtedly based upon the fact that this species is often the only plant found growing in some otherwise-barren areas. But a picture is worth a thousand words when it comes to disproving mis- and dis-information. As clearly seen here and in many other photos I’ve taken, even the most-adored plants (in this case, Dutchman’s Breeches, Dicentra cucullaria) can grow and bloom(!) in the vicinity of Garlic Mustard. |
ALL TEXT AND PHOTOS © Marlene A. Condon
NOTE: The term “nativist” employed in this article refers to an advocate for policies that support the protection of native plants by removal of “invasive” alien plants.
“Blue Ridge PRISM [Partnership
for Regional Invasive Species Management] Inc began as a volunteer-driven
organization dedicated to reducing the negative impact of invasive plants in
the northern Blue Ridge Mountains of Virginia. Effective invasive plant control
is a community and neighborhood issue because these aggressive plants know no
boundaries – flowing water, birds, hikers, vehicles, and animals [sic] scat all
help to spread their seeds.”
https://blueridgeprism.org/about/
I don’t see how anyone
could write that supposedly invasive plants are “aggressive” when it’s immediately
stated that they are being spread by other entities. The
statement is nonsensical and perfectly epitomizes the entire “invasive-plant”
narrative: Blame plants for simply responding to environmental conditions.
Nativists don’t recognize that by their own articulation of the “problem”, they
expose the fatal flaws in their thought processes: a lack of perception and reasoning
ability.
Consequently, this
organization commonly promotes misinformation that often employs an unhealthy
dose of anthropomorphism. For example, the subtitle of a Blue Ridge PRISM
"fact" sheet on Garlic Mustard (Alliaria petiolata) by
Susan A Roth declares that Garlic Mustard is a “beastly invasive” that
“[m]urders crops, [w]ildflowers, and [f]orests, [p]oisons the land” and
“[k]ills butterflies”.
https://blueridgeprism.org/wp-content/uploads/2021/09/Garlic-Mustard-Factsheet-2021-9-9-v1-FINAL.pdf)
The clear intention of Ms.
Roth’s hyperbole is to make you believe you must rid your yard and neighborhood
roadsides of this medicinal and culinary herb. But let’s look at the facts
instead of PRISM factoids.
The fourth sentence of this
PRISM “fact” sheet states that, “By now, garlic mustard is destroying forests
and killing butterflies in 34 states, ranging from the Northeast and
Mid-Atlantic to the Midwest into the Pacific Northwest and Alaska.” This kind
of overstatement is common in nativist attacks on so-called invasive plants, as
is the fact that appropriate references are rarely provided to presumably
support such exaggeration—as is the case with this web document. A lack of
references should make the reader suspicious of the validity of such rhetoric, and
with good reason, because it’s usually scaremongering based upon hearsay.
For example, the second
paragraph tells us, “Within ten years of its arrival in an area, garlic mustard
can take over the forest floor.” Really? I have just celebrated living in the
same house for the past 37 years. My yard, in the shadow of the Blue Ridge
Mountains, is surrounded by forest. Garlic Mustard grows in this area, but I
can truthfully declare that it has made no attempt to “take over” the forest
floor that surrounds me, and has only appeared in my yard twice—both times disappearing
after setting seed.
Instead, Garlic Mustard
has stuck to roadsides where the highway department distributes its
seeds by sending out mowers in the fall (after the plants have gone to seed). Thus,
Garlic Mustard’s spread can be directly attributed to people, as is typically
the case with so-called invasive plants. And, if you don’t understand the true
source of a problem, you are never going to be able to fix it (in this case, by
mowing before Garlic Mustard has set seed).
In horticulture, the
saying, “Right plant, right place” should tell everyone that plants grow only
where environmental conditions are right for them. In other words, if
conditions (amount of light, soil tilth, moisture) were conducive to
native-plant growth in a particular area, those plants—rather than alien
plants—would have come up and filled the area instead. Of course, it’s
difficult for that to happen when the highway department keeps roadsides cut
and the soil compacted, as well as polluting the soil with a salt slurry in
winter. Let’s face reality here:
Human-maintained roadsides invite the toughest of nonnative
plants to move in while discouraging less resilient native plants
that can’t withstand such harsh growing conditions.
Yet, according to nativist
postulation, garlic mustard should have “invaded” the forest floor and taken it
over long ago in my area, which simply has not happened. Why? Because this
plant needs a measure of sunlight and soil disturbance that you will not find
in undisturbed forests.
So how did this myth of
taking over forest floors get started? I suspect it’s because people don’t
scrutinize what they’re looking at. Garlic Mustard growing along trails into
the forest is simply following a cleared pathway of exposed soil. The extent of
their spread away from the path depends upon how much the surrounding forest
has been thinned (thus allowing sunlight to reach the ground) and whether the
soil is covered with enough leaf litter (so soil is not exposed).
In other instances, Garlic
Mustard spreads where trees exist but aren’t mature enough to create a forest
canopy that adequately shades the soil and covers the ground with spent leaves.
Many people incorrectly describe such areas as “forest” when they are more
properly called “woods”. Terminology matters. If a writer uses
misleading words, he misleads his reader—which is archetypal for papers about
“invasive” plants.
Now, how about those
butterflies being killed in 34 states? Naturally, no reference was supplied by Ms.
Roth, the author of the Blue Ridge PRISM “fact” sheet. So, I tried to find this
information online.
The first paper I looked
at was from the Urban Forest Alliance in McLean, Virginia, where the text was identical
to that of the PRISM paper. Worse yet, the first suggestion supplied
at the end of the paper for “more information” was the PRISM “fact” sheet! As
is common with so-called invasive-plant articles by nativist advocates, one
paper references another that either replicates exactly the text (as in this
case) or repeats the message, albeit in different words. When trying to verify
information, you go around in circles because valid information does not exist
in articles written by nativist environmentalists.
Even when looking at
more-recent scientific papers in which references are cited, you often find
that the researchers don’t seem to have read them because the papers referenced
don’t concur with what the scientists are putting forth. For example, many
scientists proclaim that Garlic Mustard is the cause of the decline of the West
Virginia White (a butterfly), and virtually all these folks reference a 1971
paper by S.R. Bowden, an English lepidopterist (one who studies butterflies and
moths).
It took over a year to
track down this paper that people greatly reference as providing proof of the
toxicity of Garlic Mustard to the West Virginia White’s caterpillar, as well as
the supposed ineptitude of the female butterfly by claiming the ovipositing
(egg-laying) female often makes the “mistake” of laying eggs on nonnative Garlic
Mustard.
First, the Bowden paper
that gets referenced so often did not prove the female West Virginia White
makes the “mistake” in the natural world of laying eggs on Garlic
Mustard, a plant that’s not palatable to her larvae. Bowden performed what I’d
call, “terrarium science”, in which the female had no choice but to lay her
eggs on the plants this man made available to her in an enclosed
environment. When you have eggs to lay and your choice is a glass surface or an inappropriate plant, you’re going to hope for the best and go with the
plant (your young need to eat, after all).
Second, while most people
referencing this paper claim the caterpillars were “poisoned” by Garlic
Mustard, that is not at all what happened in Bowden’s lab. The caterpillars
refused to eat this plant, not unlike a hungry child refusing to eat broccoli!
As a result, the caterpillars died from starvation, but the word “poison”
connotes evil and is undoubtedly the reason so many native-plant advocates use
it when discussing Garlic Mustard and its effect upon the West Virginia White. Always
keep in mind: Words matter.
References matter, too. I could not find one reference about butterflies
being killed by Garlic Mustard in 34 states, nor could I find a reference to particular
butterflies other than the West Virginia White (Pieris virginiensis)
being threatened by this plant species. Still, a USDA Forest Service document states
that Garlic Mustard posed “a severe threat to the long-term survival of the
West Virginia White in many areas [throughout much of its historic range]”, yet
also clearly declares that “Forest clearing and fragmentation appear to be
the greatest threats [emphasis mine] facing this species.”
https://www.fs.usda.gov/Internet/FSE_DOCUMENTS/fsm91_054237.pdf
These folks condemn
Garlic Mustard, as if it’s obligatory, despite admitting that other threats to
this insect’s existence are far greater. In addition to the loss of habitat
due to logging or clearing for agriculture and development, additional menaces
include insecticides and herbicides employed in nearby agricultural fields and
control efforts for Gypsy Moth outbreaks; deer browsing of native plants; and
the effects of climate change (local weather).
And another paper, “How
Environmental Conditions and Changing Landscapes Influence the Survival and
Reproduction of a Rare Butterfly”, points out that even though this butterfly
is considered rare, “P. virginiensis is frequently overlooked as it
flies early in the spring in forested areas, which are not major sources of
butterfly diversity and thus are not often regularly monitored” by butterfly
monitoring organizations.
Obviously, employment of
the West Virginia White to disparage Garlic Mustard exemplifies what goes on in
“invasive-plant” bashing. First, a likeable “victim” (that may not actually be a
victim) is found that will (presumably) make people care enough to take the
desired action (getting rid of an “invasive” plant) to “save” it. Second, accusatory
overstatements—employed to implant images in people’s minds that aren’t valid—are
boldly put forth with very little evidence provided to back them up. Dishonesty
is the hallmark for how nativists manipulate people to do their bidding.
In summary, lies (about
alien plant species), hearsay (from other nativists), and ignorance (a lack of
true botanical knowledge) form the basis of the “invasive-plant” movement.
NATURE ADVICE:
When people have an agenda, you need to be wary of their words. Don’t just buy into what you read or hear. Make your own observations of so-called invasive plants to find out if our wildlife makes use of them and how so, and if research papers are referenced by native-plant advocates, be sure to look them up. These papers often do not corroborate the claims nativists make.
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