Ponderosa Pine roots - Ask Extension
I have a large Ponderosa Pine with roots that are heaving my asphalt driveway and I'd like to know if cutting those roots could harm the tree. There...
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Ponderosa Pine roots #491693
Asked October 24, 2018, 3:11 PM EDT
I have a large Ponderosa Pine with roots that are heaving my asphalt driveway and I'd like to know if cutting those roots could harm the tree. There appear to be three roots. See photos below. Thanks.
Jefferson County Colorado
Expert Response
Hello,
Cutting the roots could harm the tree. Cutting these main structural roots may interfere with the movement of water and nutrients up to the crown, so the branches of the cut roots may die. In our heavy Colorado soils, tree roots typically grow in the top 6-18 inches of soil where they can get sufficient oxygen, and may grow upward toward the soil surface to reach their optimal zone. If the root zone is covered by concrete or asphalt, the roots are strong enough to push through it. Pines are one of the varieties that tend to heave driveways. See "Healthy roots and Healthy Trees": http://extension.colostate.edu/docs/pubs/garden/02926.pdf.
Management can be challenging, for sure. If you patch the asphalt, new cracks will likely form. If you decide to replace the driveway, using gravel or crushed rock would be best for the tree roots, and prevent future cracking, but wouldn't provide the smooth surface.
Best regards,
Cutting the roots could harm the tree. Cutting these main structural roots may interfere with the movement of water and nutrients up to the crown, so the branches of the cut roots may die. In our heavy Colorado soils, tree roots typically grow in the top 6-18 inches of soil where they can get sufficient oxygen, and may grow upward toward the soil surface to reach their optimal zone. If the root zone is covered by concrete or asphalt, the roots are strong enough to push through it. Pines are one of the varieties that tend to heave driveways. See "Healthy roots and Healthy Trees": http://extension.colostate.edu/docs/pubs/garden/02926.pdf.
Management can be challenging, for sure. If you patch the asphalt, new cracks will likely form. If you decide to replace the driveway, using gravel or crushed rock would be best for the tree roots, and prevent future cracking, but wouldn't provide the smooth surface.
Best regards,
Mari -
Thank you for getting back to me. You confirmed what I had suspected. Unfortunately I really don't have any choices other than cutting the roots and just hope for the best. I would hate to lose the tree but I'm afraid the driveway will only get worse. I am concerned, however, about the stability of the tree without these roots. Especially with them being on the north side of the trunk where we get our strongest winds.
So if I do elect to cut the roots would you have any tips for how this should be done? Should I seal the stub? Thanks. - Marcus
Thank you for getting back to me. You confirmed what I had suspected. Unfortunately I really don't have any choices other than cutting the roots and just hope for the best. I would hate to lose the tree but I'm afraid the driveway will only get worse. I am concerned, however, about the stability of the tree without these roots. Especially with them being on the north side of the trunk where we get our strongest winds.
So if I do elect to cut the roots would you have any tips for how this should be done? Should I seal the stub? Thanks. - Marcus
Hello Marcus,
If you must prune the roots, I suggest not pruning all at once. Choose one or two major structural roots to prune each year, allowing the remaining roots to take over for the one you have pruned out. This may be an ongoing process, since the tree will form new roots to replace the old ones.
The only thing I can think of to prevent new roots from growing under the driveway would be to submerge some kind of barrier to wall off the driveway so that roots cannot invade. This will not be good for the tree, so canopy damage may follow. An interesting thing about conifers is that they grow in a spiral: any damage to the roots will show up as a spiral pattern in the canopy corresponding to the branches served by that root.
Regards,
If you must prune the roots, I suggest not pruning all at once. Choose one or two major structural roots to prune each year, allowing the remaining roots to take over for the one you have pruned out. This may be an ongoing process, since the tree will form new roots to replace the old ones.
The only thing I can think of to prevent new roots from growing under the driveway would be to submerge some kind of barrier to wall off the driveway so that roots cannot invade. This will not be good for the tree, so canopy damage may follow. An interesting thing about conifers is that they grow in a spiral: any damage to the roots will show up as a spiral pattern in the canopy corresponding to the branches served by that root.
Regards,
