Q.
I have a lemon tree with some possible “issues”. It has been in the ground 10
years, about 8 feet tall, but recently the leaves are turning yellow to brown
and the branches are losing leaves in some spots. There is about 3-4″ of
rock under tree and thick weedblock under the rock.
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| In our Mojave Desert soils sometimes using rorck mulch on the soil surface can create problems. |
A.
If you read my column regularly, you may know what I’m about to say. In our
desert soils, placing rock on the soil surface beneath fruit trees is a no-no. You
might get away with it in other deserts where there has been some form of
agriculture, but not here. Frankly, I’m surprised it has taken 10 years for the
leaves to begin yellowing and browning. That may be a new record!
If you read my column regularly, you may know what I’m about to say. In our
desert soils, placing rock on the soil surface beneath fruit trees is a no-no. You
might get away with it in other deserts where there has been some form of
agriculture, but not here. Frankly, I’m surprised it has taken 10 years for the
leaves to begin yellowing and browning. That may be a new record!
Soils are made up of two major
components; the mineral component which is sand, silt and clay and organic
component. Our desert soils are extremely low in the organics; the “good stuff”
that make soils come alive. We refer to this component as the organic component
or “organics” or “organic matter” of the soil.
components; the mineral component which is sand, silt and clay and organic
component. Our desert soils are extremely low in the organics; the “good stuff”
that make soils come alive. We refer to this component as the organic component
or “organics” or “organic matter” of the soil.
Organics in the soil should rot or
break down over a few years and disappear if not replaced regularly; every year
in vegetable and herb beds or at least every 2 to 3 years around trees, fruit
trees and shrubs. Trees and shrubs that originate in deserts, i.e., desert
adapted, can tolerate soils with little organics in them. But that’s not true
of plants that don’t come from deserts. This includes citrus.
break down over a few years and disappear if not replaced regularly; every year
in vegetable and herb beds or at least every 2 to 3 years around trees, fruit
trees and shrubs. Trees and shrubs that originate in deserts, i.e., desert
adapted, can tolerate soils with little organics in them. But that’s not true
of plants that don’t come from deserts. This includes citrus.
Your lemon tree is “behind the
curve” regarding organics in the soil. The soil is probably extremely depleted.
Adding compost or other sources of organics to the soil surface may not make
much difference for a couple of years.
curve” regarding organics in the soil. The soil is probably extremely depleted.
Adding compost or other sources of organics to the soil surface may not make
much difference for a couple of years.
I would remove the rock, punch holes
in the soil, pour compost in these holes so that compost can impact the roots
quickly. Or lightly mix compost into the upper surface of the soil. Compost tea
may help. Add a cup of compost to a 5-gallon bucket of water, stir it, let it
seep for a couple of hours and pour it over the top of the rocks. But
ultimately you must get organics into the soil near the tree roots.
in the soil, pour compost in these holes so that compost can impact the roots
quickly. Or lightly mix compost into the upper surface of the soil. Compost tea
may help. Add a cup of compost to a 5-gallon bucket of water, stir it, let it
seep for a couple of hours and pour it over the top of the rocks. But
ultimately you must get organics into the soil near the tree roots.
Check the irrigation and make sure
the tree is getting enough water. An 8-foot citrus tree should get about 20 –
30 gallons of water each time it’s irrigated. The water should be applied to at
least half the area under the tree. Next February, add iron chelate to the soil
to correct andy possible leaf yellowing due to iron chlorosis.
the tree is getting enough water. An 8-foot citrus tree should get about 20 –
30 gallons of water each time it’s irrigated. The water should be applied to at
least half the area under the tree. Next February, add iron chelate to the soil
to correct andy possible leaf yellowing due to iron chlorosis.