Garlic Mustard (Alliaria petiolata) of the family mustard family (Brassicaceae)
in europe, this plant was enjoyed for its radish-like flavor. it was used to spice fish, put in salads, and made with roast lamb. medicinally it was seen as a diuretic, and environmentally it was used to help with erosion. in america it has spread (since the mid 1800s) like, well, wildfire, and thus has made it on the non-native invasives list.
generally it seems that the major method to slow its growth is chemical (e.g. herbicides)
in my romantic mind, ideally we would become a culture that pollutes our house areas less and thus can start eating our edible growing neighborhood friends... especially as garlic mustard apparently toxic to herbivores. i hear the roots can be prepared like horseradish.
the ecological issue with garlic mustard goes as followed (or so i've heard in my local area): since the deer and other herbivores don’t eat the garlic mustard, but they do eat the toothwort (Dentaria sp.), the garlic mustard finds new spaces to grow where the toothwort was eaten away. as it does, the butterflies (Pieris virginiensis) that would normally go to the toothwort, instead go to the garlic mustard for their nectar needs, but alas, something in the garlic-y ways causes the plant to be toxic to said butterflies larva. thus you have a pollinator species decreasing.
as a person who loves stories, i think that feels like it is a bit too myopic. i don’t doubt that that chain of effects are happening, i just think we need to introduce other players. for example, we have no predators here (obviously given how suburban it is now) so the deer population has expanded insanely. they are barely responsive/fearful to/of humans and are often found chilling and eating anything they can in our front yards. the community response has been to allow some (trained, i’m assuming) individuals to hunt them via archery during specific times of year, but i don’t think we have many archers here. so a surplus of deer means they are going to eat their available food sources in greater amounts than ecologically desired.
i also read a study (Waller and Maas, 2013) that indicated we can’t just pull all the invasives out and think our natives will come back before we’ve addressed the deer population.
next factor: our local woods are also at the bottom of a hill of many houses and streets. almost every house around the area sprays their yards with a whole cocktail of herbicides, pesticides, fertilizers, and then there’s the runoff from road management s like remnants from whatever comes off of tar driveway maintenance and the salt from snow prep (the latter which is a tracked problem in the watershed). and of course there are a bunch of sewer pipelines in the woods and some old bridges and whatnot (i believe initially the woods were once mostly agricultural spaces but i’m not quite sure, though that’s important because what can grow post-agriculture varies).
so what’s missing in this garlic mustard eco-snapshot? one, a focus on human influence. the number of effects different herbicides and other chemicals can have is not well studied (at a baseline i know glyphosate has a chelating effect- meaning it can bind up the nutrients which means plants can’t access them, including natives).
the thing with invasives is they tend to be a bit hardier. garlic mustard is know to grow in disturbed spaces- ones where you have a bare patch. that includes floodplains, but more likely their journey started where native plants died as a result of erosion and suburban runoff (and by the massive deer population). houses in our area don’t just abut the woods, they are basically on them (i’ve seen people growing super green grass in december up to the creek line)- so any lawn maintenance is going right into the woods.
and with the human influence, there is this assumption that humans will pay exact attention to how much of a chemical treatment they are using, whether or not they should be spraying or lightly painting their undesired weeds, but that hasn’t born out. people take the path of least resistance.
also are they using the right products for their environment all the time or mixing and causing new reactions? and the whole problem with chemical maintenance is one, we both don’t know what else is in herbicides and pesticides if you get the already-made cocktail ones (companies not legally required to list all the ingredients), and two that means most of what’s in them isn’t studied.
pulling it all together, if we are creating a more unfriendly environment, both due to additions of chemicals and from more herbivores, how will our natives survive?
because then it’s not surprisingly new plants, with fewer to no predators will show up and take over those spaces. if we aren’t tackle the top of this trickle-down chain, will focusing all our energy on adding to that chain near the bottom slow garlic mustard or other invasives enough to allow our beloved species to proliferate? unlikely. (and that’s not even getting into the question about whether our efforts to control different species is fighting the nature cycles of ecology anyway - environments are not stable on a species level forever).
if we are truly interested in preserving the original ecological balance (which again sets up a whole story of why we chose a specific point in time to call something the origin), we’d first have to reduce our chemical management techniques in all avenues to prevent confounding influences that we really can’t track. we’d then probably have to slow the deer population (you’d think venison would be big here- people coming from montana, like my partner, are so baffled by us not hunting to eat the deer). that way the toothwort and other plants that we consider desirable could have a chance to grow and not be razed down by hungry herbivores at such high rates.
and again, i strongly believe we, as the species that brought it to the country and who ate it back in europe, we should be eating garlic mustard here. but obviously these are not possible because we are mostly removed from our foraging roots (plant identification mostly) and we’ve added things to the ecosystem that we should not ingest.
and one parting thought i've been pondering. honey bees. i haven’t personally seen it studied if garlic mustard is a pollinating flower for honey bees. i remember anecdotally reading from an environmental non-profit that honey bees get nectar from ALL mustard species plants. if that’s the case, does the environmental impact of garlic mustard have some good? like keeping a source of food for our beloved non-native honey bees?