Weighing in on Wild Parsnip

June 3, 2016

This spring I attended a session in Lanark on the spread of wild parsnip and the county’s plan to spray with Clearview to control it.  The protesters, young, articulate women, were there in force, communicated by text, worked in shifts, and generally disrupted the meeting.

They left little time for a reasoned discussion of the selection of Clearview as the pesticide of choice, so I’d like to weigh in on the risks of wild parsnip’s spread and eradication efforts versus the greater risk to the environment of the spread of DSV, or Dog Strangling Vine.

Since 2006 I have become increasingly proficient in the use of Roundup, another post-emergent pesticide.  The MNR guy told me outright that my black walnut seedlings wouldn’t grow unless they were protected from grass during the first three years of their life.  That was probably an exaggeration, but it did encourage me to take the pesticides qualification course  and maintain my certification.  Last year’s renewal turned into a one-week online course from the University of Guelph — far from a formality.  I kept wondering if I had blundered into a graduate school program by mistake, but I hung in there and survived.

Last year a French study linking Roundup to Non-Hodgins Lymphoma appeared in Lancet. This spooked me a bit, as my father died of that rare disease even though he farmed organically and had no use for pesticides — or even diesel fumes, for that matter.

So you may safely assume that I use as little pesticide on the farm as I can.  Over the last three years all of the spraying I have been forced to do has been against the steady encroachment of wild parsnip.

I believe the seeds came mixed in with sand spread on the roads in winter.  The first year of the infestation concentrated on township roads where the heaviest sanding took place the previous winter.

Birds undoubtedly find the sunflower-like seeds attractive, and have spread them around to isolated locations on our 107 acres where I have done what I could to battle them back.  My neighbour was remiss in weed control for a couple of years and the corner of his field was full of the stuff.  Now I see no more parsnip on his side of the fence, but the things are well established on mine.

I have a 12v spot sprayer mounted on my Polaris Ranger, and spray by driving to the area and having at it with a 3% solution, striking individual plants.  In cramped areas this is fine, and I’m doing pretty well around individual spruces.  It’s the open areas where it’s mixed in with grass that I have failed to control the parsnip.  Mowing the stuff just doesn’t work.  It just grows back like grass.  On the other hand, it never gets to the seeding stage, so mowing every couple of weeks is better than nothing.

Why don’t I rig up a wider sprayer and nuke the plants and the hay I generally mow, or use Clearview?  I’m more concerned about airborne DSV seeds than I am the parsnip.  I don’t want to leave bare patches of earth, as DSV has spread to within a half-mile of our farm but hasn’t established a foothold yet anywhere that I can find.  But it’s a relative of the milkweed, so its seeds blow around.

Why not use Clearview?  I don’t know it well enough.  Roundup is a crop spray, well known for its herbicidal effectiveness and very short persistence in the soil.  I own several thousand little trees which have grown through repeated spot sprayings in their vicinity.  The feedback loop is pretty slow when using a spray, so I guess I’m slow to adapt.

On Lockwood Lane last summer there was a 100 sq.  foot bare spot in roadside vegetation which clearly wasn’t created by Roundup.  It was totally dead.  I don’t know for how long Clearview’s effect lasts, and what can be planted to replace the plant cover, and when.

So my advice to those property owners in Lanark worried about Clearview spraying?  Don’t ask for a ban on road spraying.  That’s the route to disaster.  Ask for Roundup for your roadside and ditches.  After the first application you’ll likely need to qualify as an applicator yourself to complete the process.  You’ll need to spray more frequently than with Clearview, but you can be pretty sure the crop herbicide won’t hurt your water, or your frogs, and it will beat down the wild parsnip if you keep at it.

That would be a show of true commitment.  Waving cardboard signs and disrupting public meetings just doesn’t cut it in the battle against invasive plants.

Update:  CBC Ottawa has a story on their site about the dangers of wild parsnip to cyclists and children.




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