Non-toxic Blackberry spray

topic posted Thu, July 14, 2005 - 3:36 PM by  Chetana
We have about 4 acres of pure blackberries that we are tractoring over this weekend. But what to do about the roots that are still in the ground? We really need to spray, but do not want to use anything that is really toxic. Does anybody have any suggestions, something that would be easy to do considering there are 4 acres of blackberries?

Many thanks,
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  • Re: Non-toxic Blackberry spray

    Thu, July 14, 2005 - 5:41 PM
    Well, first question is why? Blackberries are about the best thing you can have there.

    If you have some crop to put in then I would say use the multi-till method or solarization.

    Multi-till you just let stuff come up and keep plowing it in until it all dies off, eventually the root runs out of stored resources.

    Solarization requires large sheets of greenhouse plastic like come in rolls. It is an excellent way to kill off everything in a piece of ground without using any toxins. It also has the advantage of upping the soil temperature if you do it in the spring so you can get a good start on things.
  • Re: Non-toxic Blackberry spray

    Thu, July 14, 2005 - 5:47 PM
    4 acres is a bit much to take this approach, but you might advertise on freecycle that you have free blackberry roots for folks who want to dig 'em up.
    • Re: Non-toxic Blackberry spray

      Fri, July 15, 2005 - 6:28 AM
      Sorry for my bitchy response about non-Pacific Northwesters. I was very tired, hot, sweaty and covered with scratches and stickers from another day of clearing blackberries on my own property. I hadn't been able to find anyone to clear them for a reasonable price so the thought of putting an ad on freecycle at least put a smile on my face. I've been in the Northwest a long time and just forgot that they're not considered weeds everywhere.

      The best time for using conventional herbicides on blackberries is in the fall, rather than in the spring. In the spring, the plants are putting all their energy out into making canes, flowering and fruiting. In the fall, they're storing the energy in the roots for the winter. So after you cut them back, use the herbicide in the fall when they start to leaf out again so it will be drawn into the roots. The vinegar doesn't kill the same way so I'm not sure if it matters what time of year you use it.

      Here are two articles, one from one of my favorite organic garden writers and educators, Ann Lovejoy; the second from an extension service/MG newsletter


      Recently I discovered an amazing new set of environmentally safe products that make brutally hard work easy. For years, removing blackberries and horsetails meant very hard work and very slow results. Now, a new product from a company called Greenergy is changing all that.

      Blackberry & Brush Blocker is a byproduct of the wine industry. Made from highly concentrated wine vinegar (about 1,000 times stronger than what you use on your salad), it alters soil pH in a hurry and the effects persist for up to a year. Spray Blackberry & Brush Blocker on the root zone (not the plant) of a big old blackberry or Scotch broom; within a day, the foliage begins to wilt.

      The concentrate takes the soil pH down to 3, a level at which plants can't survive. However, the soil biota (the living creatures in the topsoil) simply go dormant, waiting for things to get better. Until you treat the soil with lime, nothing can grow in that area.

      I immediately tried it on my gravel paths and along the driveway and learned that a really rainy day is not the best time to use this (though it worked fairly well anyway). On a dry, warm day, you can watch the weeds wither. Best of all, a single application lasts up to a year. No more weeds. Period.

      Blackberry removal is slower than weeds but, oh, so thorough. It can take six months for a large blackberry plant to completely exhaust its nutritional reserves. At that point, roots won't resprout and the cut stems can't grow new roots in your brush pile. Practice a little patience and you'll have truly dead blackberry branches that aren't going anywhere ever again.

      Scotch broom also takes a few months to die, but cut branches won't resprout, so you can cut the shrubs before or after you spray the soil.

      After the whole plant is dead, remove the roots and add a fast-acting lime product such as Super Sweet to return the pH to plantable levels. Water well, wait a week or so, then add some compost and you can plant right back into a clean, weed-free space.

      Spray Blackberry & Brush Blocker on horsetail-infested soil and they begin wilting immediately and are totally dead within a week. This works splendidly with big patches of horsetails and nettles.

      It's not so great when horsetails have infiltrated a garden bed. Since the whole bottle attaches to your hose, it isn't easy to finesse the direction of the spray. Blackberry & Brush Blocker migrates very little, spreading only about four inches wider than the spray area in the soil. However, it clearly moves differently in light, sandy soils than in heavy clays, and soil moisture content also has an effect.

      Since it is absolutely lethal to everything it reaches, prized plants could be killed unless this product is used with care. To treat an infested bed, dig up the plants you want to keep, clean their roots well, and pot them up or move them into a nursery bed.

      Next, spray the bed soil with the Blackberry & Brush Blocker and let it sit for a few weeks. When the deepest tap-rooted weeds are clearly dead (Canadian thistle or big dock weeds may need a month), add lime. Water it in well and wait a few weeks for the soil to recover its normal biotic activity. Add some fresh compost, then replace your plants in a clean bed.

      A companion product called Moss Magic also alters soil pH. This product is designed for washing down decks, patios, sidewalks, driveways and rooftops. However, if Moss Magic drips on plants beside or below the target area, they will be toasted along with the moss.

      You use Moss Magic -- like Blackberry & Brush Blocker -- by connecting the hose directly to the bottle.

      To use these products with more finesse, dilute either one by mixing 1 part concentrate with 6 parts water in a hand sprayer. Set the spray nozzle to the finest possible jet to target stray horsetails among the shrubs and perennials or to wipe out a string of creeping buttercups that have wound their way into your borders.

      However, even used like this, some lateral migration still will occur, so use these products with caution. So far, I've had good luck with this technique and have not lost anything choice.

      A third product, Weed Burn Out, contains vinegar, lemon oil and juice concentrates. It top-kills anything and can be used straight from the bottle. Weed Burn Out works fast but it takes repeated treatments to kill off deeply tap-rooted dandelions and thistles.

      A pregnant friend called it a satisfying experience -- she didn't even need to bend over to weed.


      Ann Lovejoy, a free-lance food and garden writer, lives on Bainbridge Island. She can be reached via e-mail at:

      Vinegar/Acetic Acid Recommendation In May 2002, USDA-ARS issued a press release describing their research on weed control using vinegar. The research was prompted by the or-ganic farming community’s need for an inexpensive and environmen-tally benign weed killer. Study details can be found at their Web site, Homeowners hadalready heard about purported vinegar uses for killing blackberries in a June 2001, Seattle Post Intelligencer article and had deluged Exten-sion offices and Master Gardeners for more information.Five products containing acetic acid and marketed as herbicides are cur-rently registered for use in Washington. Two of them are 25% concen-trates with instructions to dilute down to 6.25% and use on rights ofways, non-crop, and industrial lands. Three of them are labeled forhomeowner use (St. Gabriel Labs Fast Acting Burn Out RTU, Nature’sGlory Weed and Grass Killer RTU, and Greenergy’s Blackberry and Brush Block). Their acetic acid concentrations are 6.25%, 6.25%, and 7% re-spectively.Preliminary field tests in Washington State using 7% vinegar solutionsshowed results similar to the ARS study at 5%, namely lack of reliableweed control. Extension personnel in Washington are able to legallyrecommend any of the three homeowner-registered products listedabove, although data demonstrates erratic weed control. In otherwords, people should be told it might not work in their situation.We also have practical safety concerns. Acetic acid concentrations over11% can cause burns upon skin contact. Eye contact can result in se-vere burns and permanent corneal injury. The other concentrated ace-tic acid products registered through EPA and the states for commercialuse all have restricted entry intervals of 48 hours and list personal pro-tection equipment to be used by the applicator.At this time, the only acetic acid-containing products Extension person-nel can currently recommend to homeowners for weed control are the ones mentioned in the product registration discussion above. As addi-tional products are registered they can be found using the PICOL labeldatabase search feature at Authors: Catherine H. Daniels, Janet Fults
      • Re: Non-toxic Blackberry spray

        Fri, July 15, 2005 - 7:35 PM
        Actually I didn't really care about the response either way so no big deal.

        I would say it is arrogant to assume that a person has not taken into account the location when giving a response. It was no big deal to look at the profile and get an idea where they were.

        It is also equally arrogant to assume that a person does not have any experience in your area. For example I have lectured at UWASH on related matters. I spend a fair amount of time in Seattle every year.

        On the actual subject, I would not be so quick to trust any of those remedies just because they are listed as approved. Some of the worst disasters have been caused by approved products. DDT being a good example.

        Acids work by burning the plants in question, as well as everything else. This includes and all life that is in the soil. It will not come back to normal quickly or easily no matter how much lime you add. Dead is dead.

        You will be killing a lot of stuff besides the blackberries, for example, nematodes which are important predators on many harmful bugs. For another example, earthworms. They make a huge difference in the vitality of the soil.

        The simple fact is that in the end chemicals are never the easy answer you think they are, even when they try to pose under the guise of a common household term like vinegar.

        Acids make by products as they interact with other chemicals. That leads to other problems too. So it is not something to be taken lightly.

        I still say stick to physical removal first then solarize with plastic. No plant survives that kind of heat and lack of moisture and you won't be chemically altering the soil.
  • Re: Non-toxic Blackberry spray

    Thu, July 14, 2005 - 9:44 PM
    Chetana, you can tell the earlier response is not from someone who lives in the Pacific NorthWET. Here in Oregon, the Himalayan blackberry is non-native and is considered a very invasive, noxious weed. It can engulf a building in a summer. I'm currently fighting the same battle. I'm going to experiment with the new 20% vinegar herbicide (household is 5%) and see if that will work. I've had success with it on weeds that aren't as tough as blackberries, but I figure it just might be worth a try. You'll want to consider though that altering the pH of the soil will dictate what can be done with the soil for some time after. Also, I'm not sure what effect the vinegar would have on the biota.
    • Re: Non-toxic Blackberry spray

      Thu, July 14, 2005 - 9:52 PM
      Well, when 4 acres was mentioned, I kinda thought they might have been growing blackberries commercially. I'm familiar with Himalaya and know it's a problem. It wasn't explicitly stated that Himalaya was the blackberry cultivar at issue.
    • Re: Non-toxic Blackberry spray

      Thu, July 14, 2005 - 11:46 PM
      Thanks for the advice. I guess I forgot to mention in my earlier post that I'm in Oregon and that blackberries can be a problem here. Yes, they have grown about 15 feet tall up into the trees around the house...slowly engulfing the house. Yikes! We hope to clear the land to start a community organic garden or farming effort for next summer.

      I'll try testing your suggestion on a small patch first to see what happens.
      Thanks again!
      • Re: Non-toxic Blackberry spray

        Fri, July 7, 2006 - 12:49 PM
        Hiya, I'm a new member here; great buncha folks, it looks like.

        I'm another Pacific Northwesterner, who has viscious blackberries, aka "Himalaya Berries". They have fabulous, lush, big, sweet, berries. Problem is, there seems to be no such thing as a small plant, or a small group of plants. They are incredibly aggressive.

        Everyone around here loves them, and nobody wants them on their own property. We all prefert to pick them off the side of the road (if we're not worried about injesting herbicides, which only manage to kill the blackberries right next ot the road), or along river banks, where they also thrive, and aren't contaminated. I'd rather drive the 15 miles to my favorite harvest spot than have them on my property.

        Unfortunately, I have a rental house, and they snuck in while I wasn't watching, 'cause I didn't have to go by there for about five years. When I did, I found a patch about 30'x75'x15 feet tall. The main problem, other than they'll eventually take over the entire five acre lot, is that they are considered a fire hazard (yep, in this part of the PacNW, we actually dry out enough to have wildfires :) Here in Orygun, we're now REQUIRED to practice "wildfire mitigation" or some such terminology. we have to cut "ladder fuels, brush, grass, etc from about an acre around any house. This includes blackberry brambles, since they typically are filled with inflammable dead canes.

        So i was glad to see this discussion. I do wonder if any of you have attempted to kill blackberries by lowering the soil pH, as is done with this 20% acetic acid (vinegar). I'm told that this stuff will burn your skin and your eyes, and much care should be taken. It's also not cheap.

        So my question to this tribe is "have any of you ever tried to lower the pH using iron sulfate? I have heard this recommended for various purposes, and it, like vinegar, leaves no toxic residue. it also comes in granular form.

        also, has anyone had problems with 20% vinegar or iron sulfate killing trees by killing their roots? i wonder how deeply the vinegar/iron sulfate penetrates into the ground...

        Hey, thanks for any advice; happy trails!
      • Re: Non-toxic Blackberry spray

        Sat, July 8, 2006 - 1:42 PM
        If you're going to till the roots that should get a bunch of it. I haven't ever dealt with this particular problem, but my raspberries seem to put their shoots out close to the surface. I thought you might want to try corn gluten meal to keep new seeds from sprouting. It works great on everything else (hubby put it on the garden this spring and nothing is growing from seed -- no weeds, no carrots, nothing). It breaks down in about 3 months, so you could do an application now and another in the fall and it would be fine for gardening by spring.

        There's a lot of info on this on the web. I got the following from
        "Corn gluten has a N-P-K ratio of 9-1-0, or 10% nitrogen by weight. As a weed suppressant, corn gluten acts as a natural "pre-emergent" - it inhibits seed germination by drying out a seed as soon as it cracks open to sprout."

        Four acres to deal with... I don't envy you all that work. I'm a compulsive web searcher and came up with the following. Good luck!