Do you water monthly?  If I skip a month this seems to happen more often.

I never tought there could be a dieback like that in figs.
When u are pruning?  is the tree fuly dormant? 

what is the consensus? 

In Zone 5a dormancy comes early. I prune in the later half of October because potted plants have to be stored inside before the snow, slush and cold weather sets in because these condition can come unexpectedly at anytime in October.
No obvious consensus formed yet.

That is interesting Akram. I have some that will need pruning for sure and was going to do that for ease of storage but now I just might hold off until spring. Those that I have pruned for cuttings I will monitor next year to see if they had any dieback. All mine are kept in a concrete cold cellar (under a covered porch) so I'm not sure just how cold it gets in there. I'll put a thermometer in there this year to see how cold it gets.
Tyler

I never had that problem?? Wish I could help!

Teach me how my pots can stay moist all winter!

Given what you told us it's fair to assume that pruning is causing your problem.  I guess I'm going to buy some wax  :)

I would say that the tips are drying out from the open cut and low humidity.  Just put a little sealer on them and they should be fine.

Prune in the spring before buds break. Maybe that could help too.

Hi Ottawanz5,
I've not seen that on my trees. I trim my trees all year round and there is no effect on them. Often when packing my trees for the winter, I wound them - generally just after comes a bad word out of my mouth as I hate wounding my trees when I'm trying to help them.
But definitively, I have to water my trees during the winter. Outside they get what the weather gives them, and one watering can if I see the dirt in the trashcans becoming too dry.
Dry dirt could attract rodents, and I act before that happens.
In pots, they got some water last year. The dirt would be bone dry if I wouldn't and then the dirt gets hydrophobic and that's not good.
Last year I snapped a branch while tying it up. It grew a new bud this year.
I don't see why you would have such a problem.
I would try to water one tree this winter to see if it solves the issue. It could well be that from lack of moisture the wound dries out and kills the bark.
I know you said that they are all piled, but you could choose one tree from the first row .

Hi Akram
I have seen some of the same effect on some cut branches.  That is why I hesitate to cut a young single stem plant.  Of course 99% of the time the plant will shoot out new branches and recover but that can screw up your training plans. 

As you mentioned desiccation may be an issue. I will be getting some wax to seal the ends. 

I think another cause is whether the branch has healthy buds below the cut.   (Notice that some branches only grow near the tips.)
If there are healthy buds it will branch out nicely below the cut if not that branch can die and the plant will be forced to push out new growth somewhere else. 

Also I have seen recommendations that when you do substantial pruning on a plant you should give it a good watering afterwards so it can recover.