My olive trees are dying ... Help !

[Humam]

Hello everybody.
I live in Palestine and I had in my Garden 8 olive trees , they are more than 40 years old ...
Since 3 years the trees are not doing well ... I think they got a disease ...
The leaves of particular branches turned yellow then drops down then the whole branch dyes ... the disease hit branch by branch , 3 of the trees were completely infected and died ! I had also a big fig tree ... it died also within months !
I don,t irrigate the trees , they depend as always on raining , the soil is not wet (except in winter) ... I did not find any worms or insects on the trees !
I took some pictures for one of the infected trees , please help me what can it be ? and what can I do to treat them ?

 

[Plantdoctor]

Has anyone been spraying anything nearby?

 

[Humam]

no one has sprayed anything ... the disease has infected the trees since 3 years and it jumps from one tree to another !

 

[Plantdoctor]

It is difficult over the Internet, you need someone local to have a look,could be soil contamination, could be an airborne disease, are you alone with this problem or are neighbouring trees in the same way that are not on your land?