Xtremehorticulture

Leaf Yellowing on Locust Possible Sunburn and Borers

Q.
Do you have idea why some many of the leaves on my locust tree are turning
yellow?

A.
The most frequent problem with locust trees, Idaho or black locust, is borers
in the trunks. This will cause exactly what you’re talking about, yellowing of
leaves and leaf drop.
            This is followed by branch dieback. Dieback
of limbs may take a couple of seasons after the initial borer attack but if you
are not looking for borer damage early, you will see leaf drop a couple of
years into the attack.
            Borers entered the trees usually
where the tre is sunburned. This is normally on the west and south facing sides
of the trunk or limbs. Horizontal limbs may be damaged on the upper surfaces as
well.
            Check the bark on the trunk or limbs
see if it is loose. It may easily pull away from the trunk particularly on the
south and west sides. Damage is usually on larger diameter parts of the tree.
            Remove bark away from damage to
areas and clean the damage down to fresh wood. You don’t need to paint it but if
you want it painted, paint it.
            Use a liquid insecticide soil drench
to help protect the tree and give it a chance to recover during early stages of
an attack.

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