My property in western Montana has been invaded by Canada Thistle, a noxious week that is slowly taking over the world.
According to Wikipedia… “It is also a serious invasive species in many additional regions where it has been introduced, usually accidentally as a contaminant in cereal crop seeds. It is cited as a noxious weed in several countries; for example Australia, Brazil, Canada, Ireland, New Zealand, and the United States.”
Once it gets established it’s almost impossible to get rid of, and my property is surrounded by properties where the owners don’t care about their weeds. And nothing seems to eat it as far as I can tell.
I have tried pulling out as many as I can, but they often times break off at the root and inevitably grow back. I even tried using Roundup, but that doesn’t seem to do much and isn’t practical for 5+ acres.
Any suggestions on how best to tackle the problem?
Are these the kind of thing that seem to come free with every bag of mulch? My front flower bed is riddled with the prickly things! I’ve pretty much given up on donning gauntlets and trying to uproot them. Now I just cut them down as low to the ground as possible. It never ends. If Roundup doesn’t work, then you have to tackle them by hand.
Why do you want to eradicate them from 5 acres?? I’d learn to live with them and try to subdue the plants that bother you the most in your immediate surroundings. After they flower and go to seed they provide a lot of food for wild birds.
I live in a sub alpine forest region and I would like to see native plants thrive as opposed to invasive species. If I can keep the noxious weeds down for a period of time, and not disturb the soils too much in the process, the native plants have a real chance to gain a foothold and keep the invasive plants at bay… at least that’s the theory.
According to that wiki article, cutting the flowerhead off before it goes to seed, repeatedly, will eventually help. I suppose for a big chunk of land, an old-school scythe might work best.
I think there is a Canada Thistle bole weevil that kills it. University of Minnisota is pretty good about raising and selling such things. I’ll do a little more research…
First, to eradicate the pests, assuming you are not chemical adverse, 2-4-D Ester and a hand pump or (lawn) tractor mounted sprayer does a pretty much a %100 job. The stuff will take out almost any broad leaf plants so be careful around the hostas and ornamental plantings. You should be able to get a five gallon jug of the stuff in concentrated from almost any good farmers’ supply store. I got mine fifteen years ago to treat a 20 acre tract of woods and pasture and still have half of it left. If does require an annual application right about this time of year. In the first year of two you might have to make two or three applications.
Second, the problem with Roundup is that it kills everything (save generically modified crops ) but the commercial pre-mixed stuff probably isn’t stout enough to take out something as hardy as thistles.
Third, mulch that is just ground-up brush from the county road crew is full of all sorts of stuff you want nothing to do with. My particular gripe with the local conservation commission’s cheap wood mulch is that it has been loaded with Box Elder seeds that germinate into seedlings and saplings almost faster than you can say. Try a place that makes wood mulch out of industrial pallets. A place near me grinds pallets for commercial bulk mulch. If you come to them they will sell undyed, that is white mulch as opposed to red or blue mulch, for $15 a cubic yard. A pickup load is $30.
This is a terrible year in Minnesota for Canada thistle. We are required to eradicate it from our property, if possible. We’re not huge fans of herbicides, so isolated plants in our ridiculously gigantic lawn will be taken out with a torch (dehydrated rather than burned). The thistles that have infested our raspberries get pulled out by hand the day after a good soaking rain, when the soil is loose enough to release the roots. For the 500,000 of them in our ditches and shelter belts, we’ll just mow them down before they blossom if we can. I believe the county also comes along and sprays the ditches if they get too bad.
As far as the biological controls on Canada thistle, here’s the information I was able to find. It seems like the jury is still out on their effectiveness.
Canada Thistle laughs at 2,4-D then farts in it’s general direction.
Transline is a herbicide that is safe for grasses and other plants that has shown good results. The problem with Canada Thistle is that it’s roots go about three feet deep. I’d talk with your Ag Extension Office first, but I’d recommend spot treating the worst areas with Roundup if you can and follow up with the Transline.
Seriously, goats will control thistle. They are not magical, they have to be managed, but they can and will eat noxious weeds such as thistles that other grazing animals will not. Goats are increasingly used by municipalities, utility companies, etc. for larger-scale vegetation control where herbicides are inappropriate (waterways for example) and hiring labor is too expensive. Cost is midway between herbicides and human labor.
Inquire around for goat weed control companies in your area. Ask for references: there are plenty of incompetent operators out there as all you need to set up shop is some electric fencing, a stock trailer, and a source of goats.