if you have more than a few trees 20 or 30, wrapping, burying, etc is too much to do.  does anyone know of a spray to protect the trees over the winter.  thx

Hahaha.  If it was that easy we'd all have hundreds of trees ;-)
On the other hand, if there is a magical spray out there I need to hear about it too.

cheryl, i tried anti desiccants - the didn't work.   i tried fencing the in & filling with leaves, i tried large cardboard boxes from refrigerators.  didn't work.  doing nothing worked better.  do you know of any research that discusses the mechanism of die-back?  it would be nice to know what we are trying to fight off.  

I honestly don't know of any specific research, although I'm sure there's something in the older posts.  I've read that the trees can take some frosts, but any prolonged freezing temperatures will likely kill the top, although the roots will probably live. That applies to the in ground.  I would imagine for potted plants if it got cold enough the roots would freeze too.  I didn't want to take any chances so mine overwintered in the basement.  Some of the plants were out last winter in two days of 17 Fahrenheit before I brought them in and there was no die back, but then you have to deal with the problem of the plants waking up early and having low light and getting leggy if it's still too cold outside.

Maybe do a search of "winter fig protection"  or "overwintering figs."  I know some people have had success, but maybe their growing zone was higher than yours. 

This guy live in zone 5a and is doing hardcore thing for the fig.

http://www.panoramitalia.com/en/life-people/profiles/alessandro-cutrone-s-fig-garden-defies-logic/3199/

Inspire by the guy i will overwinter with with 2x4 isolate with rockwool like a house isolation but no heating.

This guy speak french in his video but his way overwinter work here in zone 5 :

This wouldn't be for large trees, but I wonder if you had one of those big ice chests if you could put a few trees in there with some kind of mulch and leave the chest in a detached garage.  Would you need to air it out every once in a while?  Would you need to water the trees?  Thoughts?

Their is a spray, Wilt Stop, but it won't work for figs as it's mostly low temps that get them. Plants that desiccate from the wind, it helps a lot. Such as western blackberries in zone 5 and 6. They can take the cold, but the canes lose so much moisture they die (roots are frozen, so they can't replenish the moisture). Wilt Stop helps a lot there. It is pinene from the pine tree, think pine tar, it puts a coat of varnish like stuff on the plant that lasts about 3 months.

i tried "Wilt-Pruf Anti-Transpirant Plant Protection "  at $84/gallon.  i sprayed 3 times over the winter - does not work on figs.  i do not think it is cold that does it.  wrapping does not keep the plant warm no more than a house without heat.  burying works in Massachusetts where the frost line is 18 or more inches.  so it's probably not the cold alone.  i was old that it was the cycling between hot & cold that confused the tree & dried out the sap si i tried "Wilt Pruf".   i tried burying a plant in saw dust - it died back - too warm?   i remain perplexed.  i was thinking to coat them with wax as the do for Rose bushes they ship, but i have no idea how that is done.  i have many negative results.  i can tell what did not work for me.  

as far as i can tell, cold doesn't hurt inground trees.
only moving cold air kills.
i wrap with insulation, but i'm convinced that the black plastic i put over is what's important.

I agree with Susie, Wind chill cold is one of key to kill fig branches,  I am at Zone 8B, Last winter, It was cold for 2 weeks at 14F, I planted couple 1 year old fig trees in ground without protection, most fig trees died back, Fig tree beside 10FT tall solid fence, no damage, one 6 years old fig tree at most windy spot, no damage.

Why fig tree beside 10FT tall solid fence without damage?, because fence block cold wind, Fig tree can handle 14F cold, but it can not handle wind chill cold below 0F.

Why 6 year old fig trees without cold damage with 0F wind ? It was cold damaged twice when It was younger, I guess that it roots get deeper with wider network and finally, it reach underground warmer soil spots, it uses this warmer heat to warm itself up, I find that near tree area, all snows melted quickly.

Sometime, I do not understand that how warping tree up to really work, and why and how it work?