[MAIPC] eradicating lesser celandine

[Rachel Bayly]

Hi Everyone,

I am wondering if any of you are expert on the eradication of lesser celandine and can help with the questions below.  (It is also called fig buttercup, latin: Ficaria verna, previously Ranunculus ficaria L.)

I am a homeowner in northern Virginia.  I have an area about 30’ x 30’ that I would like to turn into a meadow that has essentially become a mat of lesser celandine, because have been busy these last few years and didn’t realize it was such a problem.  I also have some patches that I am afraid to think about in and around some native plants — there maybe the biggest patch is 4’x4’.   Today I have been researching it and it seems to be a major problem.   It seems that any effort may be multi-year, but I am looking for whatever might be most effective in one cycle (year).  That would be ok if I weren’t trying to make a meadow now…  This also interacts with how one makes a meadow…  

Questions:

The immediate question is whether to smother it starting in November with newspaper and mulch, or to wait for the spring and try to use round-up/glyphosate with a non-ionic surfactant.  Or try one of the other ideas below.

-	Which would be best?  
-	If I smother now, can I still plant meadow grasses in the spring?  Will smothering deal with the lesser celandine, or will I just have a mess having to dig up the newspaper and mulch to deal with the lesser celandine in the spring?
-	If I use glyphosate in February/March, can I still plant meadow grasses in the spring (or possibly in the summer)? 

Last year or the year before, I did put down some newspaper over some lesser celandine in the fall and in the spring the lesser celandine was pale, presumably because it didn’t get sun, but I don’t know if in fact it died or just got weaker.  So one question is: what actually happens with smothering with newspaper?  Can smothering with newspaper be effective, even if other means of smothering aren’t?

Could smothering with cardboard be effective?  I am thinking just one layer...

Other things I found on the web.  Do you agree or disagree?  Should I try these instead of smothering or round-up?

Digging under seems not to work.  “If the plants are dug into the soil, they work their way up to the surface again, the stems bracing as they grow upward from the tubers and at every branch producing fresh tubers.”  (But perhaps newspaper stops the plant from working its way up to the surface and sunshine again?)

One source said that smothering with black plastic or deep mulch doesn’t work.  (But perhaps at least the mulch issue is the same as plants dug in the soil, and newspaper might stop the plant reaching the surface and sunshine again?   Sigh.  What’s the story with black plastic?)

There seem to be different opinions on whether glyphosate can be applied once, with a non-ionic surfactant, or should be used to drench the plant and then applied again about a week later, or should be applied once and then again a year later….

One post says that iron-based herbicides are best for lesser celandine, such as IronX, a selective week killer for lawns.  True?  Pros and cons of iron-based herbicides generally and IronX in particular?

Another post says that triclopyr-based herbicides work better.  These go by the names of Garlon and Release in such products as Turflon, Weed-B-Gone and Brush-B-Gone.  True?  Pros and cons of iron-based herbicides generally and IronX in particular?

Another post suggests adding wood ashes to the soil to raise neutrality and also “going heavy on the ashes over the lesser celandine.”  I couldn’t find any specific information on how to use it and how effective this is.  Do you have any hard information?  How-to?  Pros and cons?

Everyone seems to agree that the time to deal with lesser celandine is when it is growing, that there is not much one can do now, in the fall.  But perhaps one can dig up the tubers (subject to all the cautions about getting the whole thing)?  With wetting the soil to make it easier?  But perhaps since it pretty matted, and that can also disturb the soil and make it vulnerable, that really is not practical?  

Everyone seems to agree that digging the plants up is tricky because of the risk of leaving bits of the tubules, but some posts seem to think this is doable, at least in smaller areas.  Especially if you get a good rain during the growing season and can dig up whole root systems and put them in municipal trash (?) where it gets heated enough to kill the plant (or something).  

It seems that removing the top 3” of soil is, in principle, a solution, since the little tubular roots only go down 3”.  But that’s a lot of soil!  But is this the best approach?  

Nobody mentioned solarizing except for the one comment that black plastic doesn’t work.  Do you agree?  One person I talked to on the phone described solarizing with a blue tarp, saying that killed the friendly soil microbes and they would take a few years to re-establish, but if it killed the lesser celandine, maybe that would be worth it.  

This seemed to be the best write-up on how-to for glyphosate and manual (digging).   Does this look right?  But even this does not say one application or repeated applications — the phrase “start applications” might be repeats in one place, or in different locations.  Any clarity?


https://www.nps.gov/plants/alien/fact/rafi1.htm <https://www.nps.gov/plants/alien/fact/rafi1.htm>
Chemical
In order to have the greatest negative impact to celandine and the least impact to desirable native wildflower species, herbicide should be applied in late winter-early spring, generally February through March. Start applications prior to flowering and up until about 50 percent of the plants are in flower, around April 1, then stop. After that, control success declines and many more native wildflowers have emerged that could be killed by spray. Native amphibians would also be emerging and could be harmed. Apply a 1 to 1.5% rate of a 53.8% active ingredient glyphosate isopropylamine salt (e.g., Rodeo® which is labeled for use in wetland areas), mixed with water and a non-ionic surfactant to foliage, avoiding application to anything but the celandine. Glyphosate is systemic; that is, the active ingredient is absorbed by the plant and translocated to the roots, eventually killing the entire plant. The full effect on the plant may take 1-2 weeks. Retreatment the following year will likely be needed. Applications can be made during the winter season as long as the temperature is 50 degrees Fahrenheit or above, and no rain is anticipated for at least 12 hours. Because glyphosate is non-specific, spray should be directed such that it contacts only fig buttercup and does not drift onto desirable native plants. To minimize impacts to sensitive-skinned frogs and salamanders, some experts recommend applying herbicide in March and then switching to manual methods.

Manual-Mechanical
For small infestations, fig buttercup may be pulled up by hand or dug up using a hand trowel or shovel. It is very important to remove all bulblets and tubers. Due to the abundant tiny bulblets and tubers, all material must be bagged up, removed from the site and disposed properly in a landfill or incinerator. A major consideration when manually removing invasive plants like this is the disturbance to the soil which can encourage the target invasive as well provide openings for invasion by other exotic species. For these reasons, manual and mechanical removal is probably inappropriate for larger infestations in high quality natural areas.


Thanks for any help.

Rachel Bayly
Falls Church, Virginia


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