Can you use plastic to cover a fig Tree?

I first wrapped the fig tree with burlap and then put a plastic trash bag on it. Can I use plastic?

 

A fig in your climate is really looking for insulation and/or a heat source to get it through periods where the temperature drops below 15ºF. The plastic bag will protect it from wind but will also trap moisture and, especially if it's black, could raise the temperature high enough on sunny days to start to break dormancy and compromise its ability to tolerate winter temperatures.

Try this method Figs - Cornell Cooperative Extension