Lemon and olive: bark cracking?

[Whodatatdado]

Hi all,

I found this site while searching for info on what is afflicting my dad's trees.

He lives in San Jose, California. Sunset zone 15, I believe.

There are two olive trees and a lemon tree (all around 25-35 years old) that are showing signs of cracking on the bark.

The lemon is obviously distressed. The last two pictures show the major bark cracking.

The first two pictures show the olives. While the canopy of the olives seems fine, their bark is showing some cracking.

Sprinklers did hit the trunks of these trees, but we recently changed that.

The question I have is what happened here and are these trees goners?

 

[anora]

Thanks for sharing the detail information about olive and lemon..
Your shared pictures are most important elements for our understanding...

 

[derwoodii]

Desk top tree triage says the lemons a gonna, the Olive looks to be far better and only poor bark form in one section. Buy 2 new lemons to plant and while doing so ask the local nursery bloke his thoughts on the Olive condition.

 

[derwoodii]

Hmm that soil surface looks a wee wrong have you regraded near that Lemon as no root flare to be seen it may have been poorly treated with the new fence wall and landscape. Any hoo good site for 2 new trees

 

[MCW]

I'd say the olive will be fine and it's normal in commercial orchards to get mild bark cracking like that. The Lemon however does indeed look like she's a goner as derwoodi mentioned. That is an advanced (very advanced!) case of Phytopthera (root rot) and citrus trees are very susceptible to this if they get wet feet for too long. Cracked peeling bark like in your photo is a dead giveaway.
You have very few options when it is that advanced however either Phosphonic Acid (NOT Phosphoric Acid) or a Metalxyl based product would have helped earlier on. The only advice I can give you for that Lemon is to go and visit the Chainsaw part of this forum to decide which chainsaw to buy when you cut it down
You can see the graft union above ground which is a good thing (never cover this over with dirt) although being so old there is a very high chance the Lemon was on an older type rootstock more susceptible to root rots. A lot of newer rootstocks are less susceptible. You can see by the lack of new growth (suckers) coming out of the rootstock that it too is struggling big time so basically the whole tree roots and all is under stress. There does seem to be less bark peeling off the rootstock however (have you snapped any suckers off at all?).
A good way to tell if the tree is suffering ABOVE the graft is when the rootstock starts firing out new sucker growth. If this happens you generally find there is a scion incompatibilty with the graft or crown dieback from other reasons and you can simply regraft a new tree onto the side of the rootstock.