Folks always ask me about wild chervil and garlic mustard, two seed-propagating plant species that tend to colonize woodlines, roadsides, and river corridors. What is the window for control / removal?
I say get after wild chervil all the time, you truly do not want this plant on your property since it’s a bit of a safety hazard for exposed skin. So potato fork it out of the soil in critical chokepoints or gateways and regularly patrol “clean” areas. People worry that they’ve missed their chance once the flowers have formed. Wrong, you still have a couple weeks before the seeds are viable, and after that you have a month perhaps before seeds dry out and shake off. Focus on flowering plants; once you develop some skills you’ll recognize the smaller first-year plants which you can skip over for now. These species operate with the advantage of numbers… so success only comes if we break the seed rain and then limit introduction of new seed.
Nature operates so often with bell curves – there are always early bloomers and late bloomers. So get those of course, and then do the heavy lifting removal work right up until you notice seeds falling or find them sticking to your clothes. You can hear them fall, if you listen. That’s a good time to back off and avoid unintended spreading. Seriously, once they’re ready to fall, the seeds get Everywhere! You’ll notice too that sunny spots are typically ahead of shaded areas, so do the sunny spots first and buy yourself some time. Garlic mustard is tricky in two regards. First, it’ll flower at four feet tall, but also at four inches tall in the same square meter of ground. Then I’ve seen it do a second wave of flowering in late July / early August. So you have to be thorough.
Finally, get after these seed-producing biennials in the fall. That’s when first-year plants are prepping for the next growing season, and until the ground freezes they are easy-picking. Also easy to find, because they tend to remain green. For areas that are too heavily infested to reasonably manage, lay in some sheets of cardboard for a smother effect. Weigh them down and then leave in place through next spring or longer. Just be aware of bio-security… check your clothes and boots. Or better yet, remove the outer layers on site and quarantine these items until you give them a good clean-up.
The photo below is a good one for seeing what a large infestation looks like.
Lots of yellow, even overwhelming the Christmas trees for the moment.
And on both sides of the photo, individual plants stand out, particularly the flower heads.
The stem of wild parsnip is hollow and typically ridged on the larger plants. Those are vertical, lengthwise ridges, but smaller plants often remain smooth-stemmed.
Once the plants are dead, the entire structure dries to shades of brown, and the seeds stand on their stalks like little watermelon seeds.
Another photo highlights a single plant:
Most landscapes are impacted by a dozen or so invasive plant species. They all operate on their own calendar, and we scramble to keep up. A clean, complete extraction of the target plant generally eliminates re-sprout, but most important early on is to limit the size of the infestation by breaking the seed cycle. If you run out of time to pull individual plants, go ahead and cut, but come back through and check for late flowers. Plants like wild chervil and wild parsnip will flower at 4″ tall, so a follow-up is vital. Even if seeds are formed, you can go through and pull the plants or collect seed heads. Just be sure to dispose of that material in a designated place. And once the seeds are truly dry, once they easily shake free, it’s time to avoid that area or be extremely careful not to pick up seeds. Seeds get everywhere, that’s what they’re designed to do, and even dirt on a shovel should be considered “contaminated.”
But until that seed-drop starts, it is absolutely permissible to continue your control work. Keep pulling and cutting, just be sure to treat the vegetation with a new respect since it now carries viable seed. I’m a big fan of hotspots. No need to burn everything…. just condense these long roadside weed patches into single occasional hotspots or weed drying stations. Much easier to manage a couple of those rather than an entire roadside. You can always burn that spot or smother it later.
I tend to run tight on time in spring, so I’ll often try to get ahead of biennials like garlic mustard, wild chervil and wild parsnip with some pulling in the fall. Until the ground freezes, one can often pull the first-year plants. They’ll be the ones seeding next spring as second-year survivors, but not if they over-winter on the drying station. If time is available, some work in the fall can make spring a lot easier.
The first waves of parsnip are down. More will follow, as shall I.
Was curious to know the seed count on one particularly huge wild parsnip. I had ballparked 2500 as a good working average a couple years ago, but this trophy plant last week easily topped 15,000. Impressive.
I’m able to pull thousands in a day, targeting the most mature plants first. Since those will have viable seed earliest, it’s important to buy time and catch them. Good sunny days dry out and bake the plants very quickly – no time lost to piling or removing from site.
More long days ahead!
Be smart and be careful as you work with your landscape / farm / garden. Breaking the seed cycle is a powerful tool, and the place to do that is at critical chokepoints or gateways on your land. Keep the focus on outliers and colonizers if you already have an invasive species established, and work to bring in competition… durable native species. I don’t encourage a lot of smothering, but a heavy tarp or old plywood will absolutely smother the wild chervil beneath it. But not a blue tarp… not effective. Smothering and strip mowing can contain a patch and prevent expansion, but there’s no way around the old “patient pulling and vigilance” approach.
I’ll urge you to watch for poison ivy as well. This is a banner year…. it’s now on many of my sites, in impressive size and quantity. I attempt to leave it alone as a native plant, but it’s a tough species to work around. I see ivy as a mimic to the plants nearby. Under grapevines, it takes a similar size and color, near hog peanut the ivy is much smaller and dainty, under box elder saplings you could easily misread it for box elder. Tricky.
Welcome to GotWeeds? – the non-native invasive weed consultation, training, treatment, and information-exchange site. GotWeeds? is committed to the use of non-synthetic weed control methods, which means that toxins are out but flame treatments and manual control methods are in. Best of course to assess the site and discuss the long-term vision first, but GotWeeds? seeks to demonstrate that awareness, monitoring, and early detection are strong tools in the campaign to protect treasured landscapes. Combine those tools with some gritty, strenuous work up front, and you are well on your way to a healthy and resilient property. I can help you attain that vision.
In creating this website, one of my goals was to offer landowners an information exchange, enabling them to cost-compare treatment options for non-native invasive weeds. While all sites and infestations are unique, an information exchange can be useful in determining the most appropriate and effective approach. Should you choose to pursue non-synthetic treatments that will endure over the long term, please contact Mike Bald at firstname.lastname@example.org. Thank you for choosing wisely and thinking beyond your own needs.
Speaking with a group during a post-Irene weed consultation, Royalton, Vermont, May 2012
~Mike Bald, Founder of Got Weeds?
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Tagged barberry, buckthorn, chervil, diversity, flaming, giant hogweed, got weeds?, hogweed, invasive plants, invasives, knotweed, non-chemical, non-native invasive plant, parsnip, seeds, soil, weed wrench, weeds, wild parsnip