Yes,It is my opinion,that the very low frosty Temperature in the North and north east,might kill some viruses inside the tree when the tree is totally frosted included roots.
Of course the temperature inside the tree can go down to let say 25F,and the tree still live.
If the temp goes way lower than that then tree and virus die,and so end of story,but in the above situation,the tree survives,and when it grows again ,the virus inside it might be dead if it couldn't take 25F.
That is the idea!
This opinion is based on the same observation some people above have made,that their trees get healthier every year in ground in the cold frosty climates.
Also this opinion is because after having so many example of healthy old trees here in the north east,as for example the statement by someone that NY is full of healthy fig tree.
It is not a scientific demonstrated fact,but it could be possible that the virus,can't take frosty temperatures and live on.
One thing i can say ,it is for sure ,is that the virus does not spread to other trees here.
Gina :That assessment is just plain wrong,and it had an interest to say so.
It will hurt your fig production,and in frosty climates will make your tree die.