Q. We’re seriously considering getting rid of our turf
and taking advantage of the SNWA Rebate Program ("Grass for Cash" Program). However, not at the expense of our beautiful
fruitless mulberry. What steps do we take to maintain the health and vitality
of the tree?
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| Mulberry that might be threatened in a "cash for grass" rebate program. Most landscapers will not provide enough water in the right locations for a tree of this size to survive. |
A. Great looking tree and I applaud your efforts to keep
it although I am sure those with severe allergy problems would like to see it
gone.
As you
have discovered, the water needed to support a tree like that is nearly equal
to the amount of water applied to the lawn underneath it. The best advice I
have is to maintain the grass directly under the canopy of the tree. If you
decide to remove all the grass, then you will need to add a way to deliver enough water
directly underneath the canopy.
A method
that some people are using is to lay a coil of in-line drip emitters around the
tree in a spiral, spacing the tubing about 12 to 18 inches apart. Use tubing
with emitters spaced about 12 inches apart along its length.
The less
distance between emitters, the less time will be needed for watering. I am
guessing this method will require about one hour to deliver enough water for
the tree in a single irrigation. Other plants can be planted in this area that will
take advantage of the wetted area.
Another method,
and the one I like the most, is to flood irrigate about half the area under the
canopy with two bubblers in a constructed basin that is at least one third the
diameter of the canopy. The basin must be level so that the water does not
accumulate on one side of the basin. It
will take about 10 to 15 minutes to fill the basin with enough water to supply the
tree.
 |
| Pine tree with a bubbler and basin used to for irrigation. The bubbler releases water quickly and fills the basin. It is important that the bottom of the basin is flat. |
The most
common option is to use drip emitters under the tree. This seldom works when
keeping large, mature trees like yours healthy. You would need a very large
number of drip emitters to deliver enough water. Very few retrofitted desert
landscapes use enough to keep the tree from dying back.
 |
| This tree previously was growing in lawn. This area was converted to a rock landscape, the grass removed, to conserve water. This tree was not provided with enough water after this conversion so it began to die. |
Consider
covering the soil under the tree with wood chip mulch rather than rock mulch to
maintain good “soil health” under the tree. Good soil health was promoted in
the past by maintaining your lawn. With the lawn gone and the soil covered with
rock mulch, soil health will be severely impacted which will negatively impact
the health of the tree in a period of 3 to 5 years.
