Tackling invasive plants round 1: Blackberries
If I knew back then what I know now, I'd be much less frustrated.
After 15 years of puttering around this 2.5 acres in Clackamas County, I can say that there’s a whole lot that I wish I knew when I first moved to acreage property in regards to invasive plants.
There are areas of my property I still haven’t been to because the blackberries are so thick. And some of the other problem plants quite literally choke out all of the rest of the native plants — the plants that butterflies and other insects rely on for their life cycles.
I’m very wary of using any inputs in my garden - organic or not - and spraying herbicides is definitely something I’ve shied away from. But in some ways, my trying to treat these invasive plants gently resulted in making the problem dramatically worse.
15 years on, I’m still wary of using herbicide. But I’ve come up with a way to use minimal herbicide with maximum impact. This is a method that rarely gets discussed, so I thought I’d share it with you.
Blackberries are the most problematic plant on my property. Soon I’ll share discussions about Ivy, Cherry, Creeping Buttercup, and more.
Blackberry varieties: there are several invasive kinds, along with one native. The native is called trailing blackberry or Pacific Dewberry. The difference between the native and the invasive types are generally that the invasive kinds have thicker stems and thorns, and tend to stand more upright. But if you mistakenly pull out trailing blackberry - don’t worry - there’s plenty to go around.
Getting rid of invasive blackberries
My preferred method for heavy infestations, where there are plants surrounding the blackberries that you want to preserve. It is the easiest, most effective way that uses as little herbicide as possible. It is the also longest-lasting… until a bird poops a pre-fertilized seed on your property and starts the whole process over again.
1. Cut the vine as closest to the ground as possible and immediately paint with Stump and Vine killer. A little bottle is cheap, goes a long way, and includes an applicator. The stump, along with the roots, dies right in place, with no digging required.
Some people say this method doesn’t work until fall. Not true. There are occasionally
re-sprouts though, and you have to go over the area until the blackberries are gone.
However, I don’t believe this herbicide is effective in winter. You can still get a head start on the problem by following these tips.
2. Dispose of the above-portion of the vine. I run mine through a shredder to use as mulch all over my garden. And no they don’t resprout — trust me that they are dead.
Note: what you don’t want to do is make a pile of dead blackberry vines, which birds love to perch on, and then poop out more blackberry seeds. You’ll then have blackberries growing through the dead blackberry vines that you can’t easily treat. Small plants are easy to pull or snip and treat with herbicide. But blackberries growing up through piles of dead blackberry vines get big, and you can’t reach the base for easy treatment.
Burning: instead of shredding you can also burn the dead vines, but it is difficult to get them to dry out and burn effectively. Until summer, that is - when they are really dry. And then you’ve got dangerous wildfire conditions to contend with. I’ve lit myself on fire trying to use an accelerant to get the pile to go in the spring. Once, my neighbor had to call the fire department when one of their blackberry piles got going too strongly. Also be mindful of all of your neighbors who’ve got issues with asthma and other lung conditions. A wet pile is a smoky pile.
3. Scout constantly for resprouts and seedlings. Seedlings can be pulled easily with thick gloves when the soil is moist.
Talk about lemons into lemonade, eh?
What doesn’t work well on blackberries: most of the following methods are not selective, meaning you’ll be damaging all the other plants surrounding the blackberries. In areas such as wetlands, you’ll be damaging all the surrounding plants as well as the blackberries themselves.
-Mowing. Can help control them eventually, if you cut or mow every few days for a few years. But if you don’t keep on it constantly and over a long time, what will happen is that the plant multiplies into several shoots from the base, creating a much bigger problem. At best, you’re simply delaying the problem for another time. This method could work ok if you mow, then herbicide spot treat the plants that regenerate.
-Weed-whacking: what happens with this method is similar to the above, except now you’ve got long strands of dead blackberry vines on top of the newest growth that is regenerating below. Now you have to work your way through the thorns to get to the base of the plant to effectively treat. Keep in mind that dead blackberry thorns are even sharper than alive thorn.
-Digging: I’ve got thousands of plants to deal with, which all seem to prefer heavy, dense clay. There’s no way I’m going to get ahead of these by digging them. Especially if I want to save my back. And any root fragment that is left in the ground will regenerate, requiring more digging. If you’ve got a small infestation, this may work ok.
-Goats: eat the leaves (not the vines). And when you are tired of fighting off goats getting out and destroying your fruit trees and all your other plants, you find other homes for them. Then, when the goats are gone, the blackberries regenerate from the roots, and take off like wildfire. You would have to keep goats indefinitely for this to be a successful approach. Check out this video where I show what the area looks like after we sold our goats we kept for a few years.
Herbicide options that work:
-Roundup/glyphosphate works - but only if you spray in the fall. Then you’re still stuck dealing with the dead vine above ground. This method sucks if you’re trying to prevent herbicide drift onto other plants.
-Crossbow - if you don’t mind stinking like you bathed in solvent this might be a good one for you. Unlike Roundup, it can be used other times of year than the fall. Again, it sucks if you’re trying to prevent herbicide drift. You can’t use it near wetland and it is dangerous for the environment. Also, you still have the dead vines to deal with.
Selective methods that work:
-Pulling tools: Soil and Water Conservation districts have tools you can borrow that will help you pull the plants up out of the ground, which may be a good option if you have small infestation.
-Hand-pulling the plant up with the roots works when the soil is moist. This works if you’ve got an area of wet soil, such as in wetland or perhaps after a very heavy rain. Generally the plant has to be small and not too established.
This photo is about 20 feet away, along our same road. Being able to peer into the property, you can see there is a huge difference between a blackberry infested area and one that is being treated. There’s still a ton of work to do in here with re-sprouts and seedlings to treat.
The old dog kennel fencing panels in this photo show where goats used to roam. When we sold our goats, the blackberries and ivies grew thick through the fencing, making a huge mess. I’ve almost got them knocked back enough to pick the ugly fencing up to be able to store it elsewhere.
What invasive plants are you battling on your property?
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