My 2 fig trees got through a colder than usual NC winter OK. Recently leaves on 2/3 of the smaller tree have dried up, and the small fruit with them. Peeling the bark back just a bit reveals green, which I interpret that even the small branches are not dead (or not dead yet!). The other 1/3 with normal leaves and fruit looks fine.

I did leave my winter root-insulating burlap coffee bean bags in place too long, perhaps trapping moisture around the base. I keep learning more – just found out figs prefer drier areas (mine are in an area that gets rain runoff, although the folks that planted them about 5 years ago installed a French drain nearby). 

I was just about to prune the dead-looking side way back, when I found this forum. I really love my figs, so I am glad there is a group like this. Ideas? 
 

Welcome to the forum, I'm in Charlotte and usually with that happens it means the engergy is going some place else in the tree.  It really could be a number of things.  First make sure the tree is getting plenty of water.  We've had record high temps in the Carolinas this year so heat is a major issue.  Third, your tree could have been hit by the ambrosia beetle.  Google it....not to scare you but the beetle does major damage on fig trees.  

I would start with more water first and it would hurt to give it a weekly dose of fish emulsion.   The looks strong and healthy.  Nice Celeste fig tree you have there!

Thanks for the fast reply! I see no signs of beetles or larvae, but I'll keep an eye out. All the deadness is on one trunk, all the healthy ones on another. So you think it could be lack of water, not too much! How can I tell? 

Hi,
Welcome to the forum.
Did you make a barbecue nearby ?
A fig tree in stress would give up on fruit first. The fact that the fruit is still attached means that a violent event occurred.
Could be a fire or a chemical spread around or something cutting the sap flow ( roots eaten or stems bored ).
The tree looks to be in a shaded spot, that could be another reason.
Is that tree in the middle of your property or near a public walkway were things "could be spread" without you noticing it ?
Do you have dogs going for some watering there ? With lack of water that could get you to salt built up and killing the tree .
What kind of material did you use as mulch ? (some leaves are toxic, like the ones of the walnut tree)
I would start watering more the tree and perhaps take some cuttings just for making backup trees in case you loose that one.
I would perhaps try a big airlayer for having a bigger backup tree.

Maybe some sort of toxin? 

Figs are in backyard, protected from random acts, and no BBQ's or chemicals nearby   . Have not seen voles recently, but could have been active in early spring.
Seeing a new shoot beside the affected trunk could be a clue that roots are OK maybe? 
My big decision is how far to prune back, and whether that is urgent if there is some kind of trauma or infestation.
It gets sun most of the day.

Hi,
Thanks for the pic.
Is that true that you have two trunks ?
The trunk on the left is healthy, and the one to the right is dying ?
Try to shake the trunk on the right side to see if it comes off - meaning it lost its roots to rodents ? to rot ?
At this point, if I see correctly, I would take down the right trunk. Try and inspect it to see if you can find the cause.
Does that right trunk still have healthy leaves ? at some height ?

Such a shame a beautiful tree like that is getting destroyed. I know you scratched the bark on the upper stems, but try it on the lower trunk. 

It could be verticillium wilt which is a fungus. If this is the case you need to act fast before the fungus spreads. Take cuttings of healthy unaffected stems. The tree can be saved if given the right fertilizers and pruning. 

https://www.natlarb.com/html/verticillium_wilt.html

wow - there is so much wisdom here - so glad I found this group! Thanks. 
The larger, dead, trunk moves more readily in the ground when I tug on it. The smaller one with living branches does not. If this situation was due to root damage - do I still prune severely - or just give it a haircut, treat for the voles, and hope for a re-growth?
The right trunk has no living leaves.

Wow! That's a real shame. Sorry to see that happening.
I have no advice, I'm pretty new at this too.
Our (Northern) winter-killed trees usually bounce back from the roots.
The scary thing about your trees is that surely they are sharing roots, so it may spread if it's some bug.
Any chance the right trunk was pulled on by wind or a person, and it got severed from the roots?

It also looks like symptoms of some form of root problem like root rot. If it is, you might quickly want to start some cuttings from the remaining healthy part while you can, as there would be a risk it succumbs later.

Last photo - no sign of distress in the branches I cut to test. At least to my eye.
No sign of bug holes near branches.
The Big Question - do I cut the right side way back almost to where it leaves the ground? Or leave some of the smaller branches and prune 80% of the rest? 50%?
 

I have seen a few of these bugs - could they be a culprit?
I guess if there is any doubt about infestation, trim to the ground?
Will I see evidence in the wood as I begin to cut?
 

That looks like a picture wing fly in your photo,harmless to trees.

This is the larva of a borer that was in a fig tree that I was trimming dead wood from in the Spring.My larva does not look like an Ambrosia beetle larva.If your tree had a borer infestation you would see the holes in the bark and tunnels through the wood.
 

If it was my tree,I would paint the bare spots on the tree where you pruned the branches and wait and see if the trunk sprouts some new branches.

Make sure to water the tree regularly and hope for the best.  :)

That's a relief about the bug! By paint, do you recommend an asphalt based sealer or just a latex paint? Up to now I've just left a pruning cut natural.

I would remove the dying trunk/side ASAP hoping to help stem the spread of whatever it is to the healthy trunk. 

I use roofing tar to protect the wound from future insect damage.