lemon tree disease

Question

The branches of my lemon tree have cracked open. The bark is full of lichens, it has fewer leaves and less lemons. What can I do? Is it going to die? Will it contaminate the orange tree and the tangerine tree?

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Answer 1

Could there have been frost damage, lightning or mechanical damage at any point? This could cause the dying and cracking branches you see.

Otherwise there could be an infectious disease present. Check for any more spots with sap leaking out of the tree, since this is a symptom of several diseases. See the following articles:
https://www.gardeningknowhow.com/edible/fruits/lemons/common-lemon-tree-diseases.htm
http://ipm.ucanr.edu/PMG/C107/m107bptrunkrootdis.html