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Each summer in those parts of the world where wild parsnip goes to seed there are various small efforts to control the spread of this plant. The media have a field day, of course, "deadly", "toxic", "danger" and so on, and it keeps at least 3 reporters in work spreading the word.

Some municipalities, wishing to bow to community demands, perhaps take a tractor in with a bush hog (very big rotary mower) and do a good job of cutting the plant down but helping the plant to spread even further, and maybe put the tractor operator in hospital for a few days. Others will spray herbicide. Communities sprout small adventitious groups of committed individuals who spend effort in controlling small patches.

Given these community-spirited people as an almost free resource and your expert knowledge of the way plants (and parsnip in particular) grow and spread, how would you advise the problem be handled at least cost and maximum effect?

Colin Beckingham
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3 Answers3

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Since wild parsnip is a biennial, when I owned a couple of acres I would just wait for it to set seed, then snip the seedheads off into a five-gallon pail and burn them. I did the same for Queen Anne's Lace. This actually worked fairly well; I was able to drastically reduce the numbers of both species over a couple of years. Interestingly, it seems to me that there is less danger of toxicity from the sap in the autumn, since the plant is on its way to dying; anyway, I never got burned doing this.

I think I was fortunate, though, in that the plant was just getting established in the area and I had a couple of hundred of plants to deal with the first year, rather than the thousands that would've been present five years later if I had done nothing (estimate based on what other people's land looked like at that time).

Anything we do - whether hand-pulling (which I DON'T recommend - I was burned once myself doing that), seed-killing, or herbicides - is just a stop-gap for a problem that is NOT going to go away. Local efforts to eradicate it can help keep parks and public spaces relatively free of the weed, but I don't believe that we'll ever be able to eradicate it on a larger scale.

Incidentally, I've seen larvae of the black swallowtail butterfly eating wild parsnip seeds, much like they sometimes eat the seeds of golden alexanders. Maybe there's hope that a natural predator will emerge over time.

Colin, you're absolutely correct in that townships do more to spread weeds than prevent it. In that same area where I used to live, garlic mustard was growing in straight lines in the ditches, where it had been spread by the town's mowers.

Jurp
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  • Find a disease that hits the stuff. Hire a genetics lab to hop up the bacteria or virus to *total annihilation* strength. Release hundreds of gallons of 'spore' via airplane for a decade or three. – Wayfaring Stranger Jul 31 '18 at 14:58
  • @WayfaringStranger: ...then live with the unintended consequences of this strategy forevermore. – Bob Jarvis - Слава Україні Jul 31 '18 at 15:08
  • @BobJarvis Probably get venomous badgers or something similar out of it. – Wayfaring Stranger Jul 31 '18 at 15:12
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    @WayfaringStranger More likely: a mutation that attacks crops. – JimmyJames Jul 31 '18 at 15:22
  • Does burning these give off toxic fumes? – JimmyJames Jul 31 '18 at 15:24
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    @WayfaringStranger - venomous badgers (provisionally *mydaus crotales*), a man-made subspecies of the stink badger, were the end-product of [Dr. Evil](https://en.wikipedia.org/wiki/Dr._Evil)'s breeding program where he attempted to overthrow the World Government with foul-smelling venomous creatures. Sadly, the lack of a functional World Government wrecked his plans. My understanding is that he is now in the planning stages of his next project, Dr. Evil's Worlds of Wonder, an amusement park and planned extremely-brief-retirement community outside of Bayonne, NJ. I just can't wait! :-) – Bob Jarvis - Слава Україні Jul 31 '18 at 15:58
  • Burning plants with known irritants can result in reactions to the smoke. – Scott Seidman Jul 31 '18 at 19:37
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    @ScottSeidman poison ivy is notorious for this effect. – Wayfaring Stranger Jul 31 '18 at 19:52
  • @Scott - we never had a problem burning the seeds - and I think we also burned dry stalks on occasion - but I never burned a growing wild parsnip (I'd heard the stories about poison ivy, too). OTOH, since the reaction is activated by sunlight, I don't know if the smoke would actually harm you (maybe if it got on your skin?). I did not want to find out, though. Better to be safe than sorry... The question of whether to burn the plants or not is important, though, since a controlled burn may eradicate them from a field but, if the smoke is toxic you can't do the burn. – Jurp Aug 02 '18 at 00:17
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I wouldn't even attempt to eliminate the plant. Instead, your goal should be to eliminate it from areas where people are likely to come into contact with it. Your best bet (my opinion) is to get a group of intelligent adults together and identify high risk areas. Then, as a group you need to wet the area in order to loosen the soil around the plants and with the proper safety equipment (long rubber gloves, masks... etcetera) pull them up by their roots.

While I have zero experience with wild parsnip I do have plenty of experience with invasive plants and based on what I have learned there is no better way of handling them in a permanent or semi-permanent fashion.

Rob
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I'd suggest that you find people interested in foraging, and teach them how to take these parsnips for consumption. There might be some people also interested in harvesting them for sale in local markets. They just need to be educated about how to avoid getting the sap on their skin.

Graham Chiu
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