Knowledgebase
Removal of blackberry bushes #906482
Asked June 19, 2025, 7:46 PM EDT
Delta County Michigan
Expert Response
Hi Carmen,
You don't mention what else is growing in the septic field area. Is this a turf area? Do you have desirable plantings in the area? Or is this an area that you allow nature to take it's course? How large are the plants at the base - do you have a large 12" patch of thick stems or is a stem or two here and there? These are all factors to consider for removal.
Digging out the plants is a form of physical control. Mowing would be a mechanical control and may eventually kill off the plants by exhausting the root stores. Glyphosate is an option for chemical control. You may wish to try a combination of these. For example, you could mow down existing plants then use an herbicide to treat any new growth. That would allow you to use less herbicide than on mature plants and have the treatment in a more concentrated area. All of these control methods will take constant monitoring and reworking the area for several years.
If you've had some of the rains this past week, it may be a good time for digging out the plants.
Here are some resources:
https://extension.oregonstate.edu/news/methods-control-blackberry-thickets
https://ipm.ucanr.edu/PMG/PESTNOTES/pn7434.html
https://extension.oregonstate.edu/ask-extension/featured/blackberry-removal-tips-done-naturally
Septic resources:
Septic systems main page
Managing Septic systems
Native plants on septic fields
I responded with voice to text and I was just going over what I sent. I meant to say non-toxic rather than done toxic
Thanks for the response. The area over my septic system is mostly weeds a little grass but lots of blackberries they seem to be spreading profusely. I don't care what gets killed in the process I would rather have my septic system working and not being clogged. Most of the blackberry bushes the older ones, are about 3/4 of an inch at the base. Very thick not necessarily one here or one there. They're beginning to spread sparsely out over an area about 20 ft but I've been mowing them down. I would prefer to use something done toxic. Have you ever heard of Epsom salt and vinegar working to kill them. I was looking for an organic way of getting rid of them. Physical removal is too much for me I'm 72 years old and both of my shoulders are shot. I do have a piece of paper mill screen over the main part of the drain field and nothing seems to be growing there but the edges of this material are also right along the edge of the drain field and I'm sure the roots are working they were under. I appreciate your response I will look at some of the links you sent me thank you very much.
Hi Carmen,
You're very welcome. We often think that things that are safe for us to use in our homes would be safe to use outside, but that isn't often the case. This link from NPIC, National Pesticide Information Center is helpful.
This is another Ask Extension question about DIY herbicides with additional links as well.
You could use the stump-cut method. That greatly reduces the amount of herbicide needed. In fall or winter, you would cut back the canes and apply an appropriate herbicide (one that lists blackberries on the label) to the stump. This allows you to use minimal amounts, but be quite effective. Then, starting next year, you can mow over the septic mound when you mow the rest of the yard.
