Oleander Has Leaves That are Crunching Up

Q. I have 4 oleander bushes that were doing great, now 2
of them are drying up the leaves are turning light and they are crunching up,
what is going on. The ground seems wet enough, what is happening. I need your
help are the dying?

Freeze damage and spring recovery oleander

A. The information I think I have from you is that you
have four oleander bushes that have done well for several years and now some of
them are drying up after a previous several year history of doing very well.

I would assume that they are on the same valve so they
are getting water at the same time off of the same irrigation valve. Also
please realize that if the water was turned off for a long time, and then
turned on again, that the soil can be moist but moistened after the damage was
done.

Not oleander but pittosporum with drought stress

There is a lag time between damage to the plant where you
will see the damage (leaves are dry and crunchy) and when the damage occurred.
This could be a week or more. Visual appearance of drought damage lags behind
the actual time the damage occurs. If it was drought damage, they will recover
if water is reapplied and it is done before too long of a time (if the water is
turned off for months when it is hot the plants will most likely not recover).

The type of oleander may also dictate damage like this.
For instance the petite oleanders, with the salmon colored flowers, are damaged
with light freezes. The standard oleanders (large shrubs whites, reds, purples,
etc.) are more cold hardly. However, there are differences in cold hardiness
(dieback to or near the ground) between even the standard varieties but many of
these die back ranging in temperatures dropping below 20F and down to about
10F.

A few diseases but not much. There is one oleander
disease that has, to my knowledge, been found in southern Nevada that causes
leaves to scorch… appropriately called oleander leaf scorch disease. It has
been found in southern California and Arizona. Here is a link to some
information on the disease but it usually does not cause the entire plant to
die since you can cut it to the ground and it will regrow with uninfected plant
parts.

http://ag.arizona.edu/plp/plpext/diseases/trees/oleander/oleleaf.htm

Other rare disease problems include sooty canker and root
rots but this would be highly unlikely from your descriptions AND they
typically do not cause total plant death.

Because oleander has so few problems in our climate we
start getting into some weird and highly unlikely possibilities which center
mostly on the soil and what may or may not have been put on the soil close to
the plant. So then you have to go back into the history of how the plants were
managed. Was there anything applied to the soil near them? Fertilizer applied
right next to plants can cause scorching and even plant death.

If it persists, replace the plants and the soil in those
spots if the irrigation checks out okay.