Question
QUESTION: Hello Jim,
We have a magnificent magnolia that is old and beautiful.It must be at least 40 feet tall. Some work was done to put a walkway and and wall in that are very close to the tree on two adjacent sides. The roots have on these two sides were cut away and I am very concerned about the health of the tree.
The trunk is approximately  70" around at the base and about 60"around at 4 feet off the ground.
The walkway is only   19" inches from one side of trunk
The adjacent wall/fence is only  25" from the side of the trunk
The depth of the walkway and wall vary from about 8 inches below surface dirt for the walkway side to 14 inches on the wall side.
It appears that the root system is extensive and there are many roots at the surface all around this tree.
1)Will the remaining root system be able to support the tree?
2)what can we do at this point to help the tree make it through the loss of these roots?
Any help appreciated.
regards,
Ben in California
ANSWER: Support will not be a problem but the lack of roots to get water and food for the tree will more than likely cause the tree to experience some foliage dieback. About all that you can do now is water during times of no rain and fertilize the remaining root zone. Measure an area three times the canopy spread, then broadcast one pound (2 cups) of 8-8-8 or 10-10-10 fertilizer per 100 square feet in March, May, July and September.
Cutting roots this close to a tree is not good for the tree and do not be supervised if the foliage dies on that side of the tree.

---------- FOLLOW-UP ----------

QUESTION: Jim,
thanks for ther prompt and helpful response.

the tree is in a front yard, its the bay area of california so it does not rain from now until october. The ground in the yard is very hard compacted dirt.

About 60% of the area outside the canopy is covered with driveway/rock or street. I will water and fertize in all the areas with dirt/exposure.

Should I use a "deep root watering spike"? (not sure what they are really called"

Will the foliage that dies off come back over time. If so how long will recovery take in general.

Regards,
Ben in San Jose California

Answer
The foliage that dies back will not come back. New branches may sprout out in this area if the tree. What has happened the roots were damaged and the tree can nit support the amount of branch (foliage) so the tree gets rid of some of the foliage. As the tree adapts to its new root system it may re-sprout new foliage to replace the old but his foliage will be usually be sprouting from the main trunk not the branches that were there before. So you may end up with a tree with part of the crown missing.

It will need about 1 inch of water each week. Place a pan under the tree and water when the pan has 1 inch of water in it stop. If you have the capability of deep watering that will insure the tree gets the water rather than sharing the water with the grass.