On some citrus trees in pots, on new (triangular)
twig it always begins as bulge.
After several days bulge opens and drop appears.
Bulge disappear and open scar or pit remains on twig.
Someone says too much nitrogen in soil.

Are you talking about flower buds?

No, I think he is speaking about Cankers.

bulge on soft young twig

bulge opens and drop appears

Bulge disappear and open scar or pit remains on twig

I have also seen this once or twice.
The only reference I could find suggests it might be 'gum pocket' caused by copper deficiency in the presence (as you suggest) of high nitrogen levels.
See http://edis.ifas.ufl.edu/CH142
Mike.

Many thanks for info.
Yes, it realy looks like.

I think it is problem of soil I used to use in pots,
also multiple buds or “witches broom” are present on some young grafts and also on some other plants which I have in pots, for example longan seedlings.

Many thanks once again.
Radoslav

You can easily control it with some copper sprays.
Do not fertilize too much, give the trees some rest...
I use a high nitrogen fertilizer, and as soon as I encounter some multible bud sprouts, I give the tree a copper spray.
It prevents many fungal disease, not the tree would need, but as protection it is welcome, and of cource, it cures my trees and make them much better growing.
Most fertilizers contain not enough copper, if any... so annual copper sprays, as fungal protection and deficiency protection those sprays are recommended.