Daphne odora shrub roots - Ask Extension
First, I greatly respect extension services and thank you for your service to the community.
I live in DC and hope you answer our questions, since w...
Knowledgebase
Daphne odora shrub roots #858715
Asked February 07, 2024, 4:59 PM EST
First, I greatly respect extension services and thank you for your service to the community.
I live in DC and hope you answer our questions, since we don’t have an extension service as far as I can tell. (If we do, do you have the contact information?)
For the past 40 years, I’ve lived in a 130-year-old row house with its original sewer pipe. Roots began clogging the pipe beginning about 4 years ago and have been extremely difficult and expensive for plumbers to clear. I’m told that fixing the pipe would cost a minimum of $20,000 and probably much more.
So I’m eager to do everything possible to keep the roots in check.
I have a large daphne odora bush noted with the red arrow. The root problem begins directly under it (red spot in photo) and runs out toward the street. The sewer pipe is about 3 feet below the sidewalk level, so about 7 feet below the daphne foliage.
I’ve learned that daphne has deep roots. Question 1: Might the daphne be the cause of the root problem under it?
Much of the root intrusion undoubtedly is from what I’m told is the swamp maple in the tree box that was planted by DC.
Question 2: Plumbers suggest that I alternate using RootX (dichlobenil) and Roebic K-77 (copper sulfate) to keep the roots in check without harming the daphne and swamp maple. What are your thoughts on this?
District of Columbia County District of Columbia
Expert Response
UMD has answered DC inquiries in the past, but during last year UDC began to answer questions from DC residents. We will direct your question to them if they wish to join the discussion, but are happy to provide some cursory feedback.
As a preliminary assessment, our best guess is that the Daphne is not responsible (or, at least, not by itself) since Daphne are notorious for being challenging to grow long-term in our region based on their intolerance for clay-heavy, poorly-drained or compacted soils. (Notorious to the extent that even long-established specimens in public gardens have been known to die seemingly suddenly one year.) Therefore, we would guess that Daphne roots would avoid a source of consistent moisture, though the maple (it looks like Red Maple, Acer rubrum) is a likely culprit, as you noted, since that species handles compacted soil better and thrives in wetter soils than many other shade tree species.
To the best of our knowledge, roots cannot break into an intact pipe; there must be a pre-existing leak or joint that has a weakened or incomplete seal that they can wedge themselves into in order to infiltrate a pipe. They can't "sense" water inside a pipe that they cannot grow into, and therefore won't necessarily grow preferentially in its direction. Of course, in areas with limited root space, tree and shrub roots will grow wherever they can to get enough oxygen, moisture, and nutrients to survive. You could verify this assumption about pipe intrusion by consulting a certified arborist (perhaps one of the city arborists), who may also be able to address the questions about pesticide use reliability and recommendations for root growth control.
We at HGIC in UMD Extension do not have information about root control techniques with regards to chemical treatments. Copper is a component in certain fungicides used to suppress foliar plant diseases, and there are often cautions on the product label in those cases limiting how many applications can be made per year in order to reduce the risk of toxic levels building up over time in the soil. The same may be true for a soil-applied product for root control; copper can be toxic to roots, killing root tips and hampering growth, which is also why some nursery plastic pot manufacturers line the inside of new shrub/tree pots with a microscopic layer of copper to discourage root circling as the plants begin to outgrow their container. Once in the soil, copper may be hard to remove if levels were to become too high, so this is an important consideration. It might be worth investigating if the pipe itself can be better secured/sealed against root intrusion instead, though admittedly the digging involved to do so may endanger the Daphne's survival if too many of its roots are disturbed or damaged in the process.
If UDC has additional resources or information to share about this dilemma, their reply will appear in this same discussion thread.
Miri
As a preliminary assessment, our best guess is that the Daphne is not responsible (or, at least, not by itself) since Daphne are notorious for being challenging to grow long-term in our region based on their intolerance for clay-heavy, poorly-drained or compacted soils. (Notorious to the extent that even long-established specimens in public gardens have been known to die seemingly suddenly one year.) Therefore, we would guess that Daphne roots would avoid a source of consistent moisture, though the maple (it looks like Red Maple, Acer rubrum) is a likely culprit, as you noted, since that species handles compacted soil better and thrives in wetter soils than many other shade tree species.
To the best of our knowledge, roots cannot break into an intact pipe; there must be a pre-existing leak or joint that has a weakened or incomplete seal that they can wedge themselves into in order to infiltrate a pipe. They can't "sense" water inside a pipe that they cannot grow into, and therefore won't necessarily grow preferentially in its direction. Of course, in areas with limited root space, tree and shrub roots will grow wherever they can to get enough oxygen, moisture, and nutrients to survive. You could verify this assumption about pipe intrusion by consulting a certified arborist (perhaps one of the city arborists), who may also be able to address the questions about pesticide use reliability and recommendations for root growth control.
We at HGIC in UMD Extension do not have information about root control techniques with regards to chemical treatments. Copper is a component in certain fungicides used to suppress foliar plant diseases, and there are often cautions on the product label in those cases limiting how many applications can be made per year in order to reduce the risk of toxic levels building up over time in the soil. The same may be true for a soil-applied product for root control; copper can be toxic to roots, killing root tips and hampering growth, which is also why some nursery plastic pot manufacturers line the inside of new shrub/tree pots with a microscopic layer of copper to discourage root circling as the plants begin to outgrow their container. Once in the soil, copper may be hard to remove if levels were to become too high, so this is an important consideration. It might be worth investigating if the pipe itself can be better secured/sealed against root intrusion instead, though admittedly the digging involved to do so may endanger the Daphne's survival if too many of its roots are disturbed or damaged in the process.
If UDC has additional resources or information to share about this dilemma, their reply will appear in this same discussion thread.
Miri
Thank you so much for this speedy and extensive reply, Miri!
On Feb 7, 2024, at 5:33 PM, Ask Extension <<personal data hidden>> wrote:
Thank you for your question. As Miri said, UDC has recently commenced responding to such questions for DC residents, working closely with UMD (and with lots of support from UMD too). However, as you pointed out, the link is not readily available. We hope to have the link up on the UDC website shortly.
We agree that an arborist may be of more use to you. In addition to the link that Miri gave you, we suggest that you try Casey Trees who work extensively in DC and really know trees!
Lesley
