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Tuesday, January 22, 2013

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.

The number one problem is a lack of water. I usually try to focus on the easiest possible reasons first because they are the most common. I realize your reaction will be to say it is not that but please check to make sure the water source has not been blocked, if this is drip irrigation, or reduced dramatically.

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.

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.

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