Rooty Garden Beds

[cassidy]

We're gardening in Reno, Nevada (Zone 7a) and have had some raised garden beds in the backyard for maybe 10 years now. Over the past 3 to 4 years, we've begun to have issues with some sort of weed creating a pretty extensive root system in several of the garden beds. The root system is made up of many small, fibrous roots; none of them have a circumference any larger than pencil lead, and they seem to be woody and dry (as opposed to fleshy or soft). They penetrate all the way to the bottom of the garden beds and create such a tight mat that it almost seems to be more roots than soil at this point. The thing that I can't wrap my brain around is that these roots haven't put up any vegetation outside of the soil, so I can't identify what it is or where it's coming from. The only weed that we see uniformly across our garden beds is Oxalis corniculata (Creeping wood sorrel/ Yellow sorrel), but even this isn't popping up in one of the heavily rooted garden beds. We also have an ivy (not sure on the genus or species) that grows along one side of the backyard that could also be the culprit but it doesn't get anywhere near some of the rooty garden beds.

Any ideas on what this could be or how to manage it? We tried occultation tarping one garden bed for several hot weeks this summer, but I'm guessing it wasn't nearly enough time to kill the weed. Our leafy greens seem to co-exist with it just fine but we do grow a number of root veggies (potatoes, horseradish, burdock root), and I'm worried that the yields might suffer if we don't do something.

Thank you so much for any ideas or suggestions!

 

[Marck]

Greetings, welcome to the Forums.

This is an unusual and interesting situation. It would be wonderful to see a close, detailed photograph of these 'roots'.
Could this be a fungal mycelium?
If so it may be a beneficial or harmless, since the OP states that leafy plants grow fine in the same soil.

 

[cassidy]

Marck,
Thank you so much for getting back to me! I haven't dived into the world of identifying fungi but I've attached some photos of what the roots look like if you might have a better idea. They are pretty woody and I can definitely pick out xylem and phloem inside, but perhaps certain mycelium can appear to have these structures as well?

 

[Marck]

Yes, I agree with you, This does look like a mat of roots. Some of it looks dead but some of it looks to be still alive. Some of it could be rhizomes of a perennial weed, for example Bindweed (Convolvulus arvensis), but then you would have seen leaves and stems, lots of them. How long has it been since you saw any weed foliage growing in the beds? Perhaps it is roots from a nearby shrub or tree, or the ivy (Hedera helix?) that you mentioned before.

 

[cassidy]

The roots seemed to have showed up 3 or 4 years ago but really became matted and thick this past growing season. It does seem likely that they come from a perennial; they survive the winter just fine. I wouldn’t put it past the ivy in our backyard to have made it all the way over to the garden beds, do you think it’s possible the roots traveled underground and then up into the garden beds?

 

[Marck]

It may be possible. A photo of the layout of the beds and Ivy would help to understand that likelihood.

From the evidence presented so far, the roots seem to be coming form a plant some distance from the bed. As plant growth in the bed does not appear to be affected, my only recommendation is to turn the soil in the bed at the beginning of each planting season, so as to break up and reduce the root mass. Dead and severed roots will provide more organic matter to the soil and do not need to be removed..

 

[Marck]

Here is another Garden Forums thread that caught my eye. Evidently, others have also encountered alien root mats in raised beds.
https://www.gardening-forums.com/threads/what-is-this.6678/

 

[Oliver Buckle]

My first thought was "Is there a large tree within thirty or forty feet of the bed?". Those do look similar to tree roots and if you are treating your beds well, watering and fertilising, they would put on extra growth in the area to take advantage of it.
My experience of ivy is that it can send out runners for a considerable distance, but they tend to be near the surface. You could try driving a spade into the ground between the ivy and the bed (closer to the ivy) to cut through anything coming from it.

 

[DirtMechanic]

Cut deep around the garden in a trench. Rent a trencher even. The cut off roots become fertilizer after that. Y'all are making my head hurt.