We agree. Star of Bethlehem is a frustrating bulb to get rid of.
Here is our page on it: 
https://extension.umd.edu/resource/star-bethlehem/
Is it in a lawn area or garden bed?
As you probably know, most areas of Montgomery County (other than Laytonsville) have regulations against using pesticides/herbicides in lawns.

Lesser Celandine is a bit different though and it shows as exempt so that you can treat it: 
https://www.montgomerycountymd.gov/DEP/property-care/lawns/law/exemptions.html
The treatment for Lesser Celandine has a very narrow window of timing for application though-as in now-  see here: 
https://extension.umd.edu/resource/lesser-celandine/
You could use a non-selective herbicide containing glyphosate.  A 'sticker/spreader' such as Turbo needs to be added to adhere to the leaf.


Christine

Hello Eva,

We are not aware of any local government-led eradication efforts other than general programs like Weed Warriors that train volunteers to recognize and remove invasive weeds. We would not be surprised if, at the federal level, scientists are researching potential biocontrol options for some invasive species. (Biocontrol is the process of using biological agents, like an insect that consumes that particular plant, as a way to keep that plant's spread in check. One reason invasive species are so successful in new habitats is because there is no natural predator present that reduces their vigor or spread.) Biocontrol agents have to be extensively and carefully tested, though, so they don't also become pests themselves for our native species.

Extension doesn't maintain a list of every product available (and manufacturers do sometimes alter their pesticide formulations), nor do we make brand recommendations, so we don't have a specific suggestion other than using a systemic herbicide so it will be absorbed by foliage and moved into roots to kill the entire plant. If treatments are applied too close to dormancy (after flowering has finished), Lesser Celandine won't be well-controlled by even those herbicides. They will still go dormant, which can make it look like a treatment worked, but will reappear the following spring.

Spreader-sticker is one term for what is otherwise called a surfactant or adjuvant, all of which just means it's an additive for pesticides that helps the spray stick to the leaves long enough to be absorbed. At least one brand might literally name their product "spreader sticker," but you'd have to see what's available. Both of these weeds have such waxy, water-repellent coatings that using a spray without a spreader-sticker might not work very well. However, since each herbicide formulation is unique, one must verify the product label allows for a surfactant / spreader-sticker to be added, and if so, what type. Such products tend to be sold alongside pesticides at garden centers, since it's not uncommon for them to be used together, so check each product's label for directions for use.

The most oft-recommended active systemic ingredient for control of hard-to-kill weeds is glyphosate. This is the same ingredient common to many (but not all) Roundup products, but not all herbicides using glyphosate are Roundup brand products. Herbicide packages will always list the active ingredient(s) on the label; some use only one while others have a combination of several. In this particular case, the systemic by itself is probably the most important ingredient since others should not be necessary for these two weeds.

If you prefer to avoid herbicides, the only recourse is the continued physical removal of all weed growth, above and below-ground, as often as it reappears. Sifting celandine bulblets out of the soil will be tedious and it's common for diligent gardeners to still miss some, which will reappear the following spring. The process repeats itself until they are gone or so few come up that they can be spot-treated with herbicide or suppressed by nearby aggressive native species. (Planting natives by itself will not be enough to out-compete them, though.)

It's key to remove as much of the weed as possible, such as digging up the bulbs for the Star-of-Bethlehem, or else the plants will just keep sending up new foliage from the stored energy in their roots. The longer foliage remains on any weed, the more it can "recharge the batteries," so to speak, of stored energy for growth in the roots. Every time they regrow, they are forced to use-up some of that energy, so by making them continually resprout, you can run-down that battery to its depletion, but only if leaf removal is prompt and someone is vigilant for new growth. The difficulty using this method on bulbous weeds like celandine, though, is that the plant is used to losing foliage very early in the season as it goes dormant, so depriving it of photosynthetic time is going to have less of an impact (unless you perhaps can get to it beginning as soon as it first emerges), and thus the removal process will likely take even longer.

Once a weed is removed, such as from a natural area, a plan should be in place to discourage its reintroduction by planting site-appropriate native species in its place. Deer movements could be one factor in continuing Lesser Celandine spread, though stormwater flow shifting bulblets around is another typical route of spread for this plant. This is one reason why efforts to eradicate invasive plant colonies in natural areas is challenging; enough labor and budget resources have to be available to maintain either follow-up herbicide treatments, manual removal, planting and care or replacement installations of native plants (and the nursery availability of those plants), managing excessively high deer populations, stormwater and other erosion problems, and so on. Priorities are probably given to species just beginning to act invasively so they can be managed before they get established, rather than for species already overwhelming degraded habitats. It's unfortunate, but it's the reality for many agencies hampered by limited budgets and labor to tackle and ever-growing array of invasive species.

Miri