Boeing allow take off with "fuel frost" on the upper wings of 737-700 within a painted black line area. This is caused by landing with lots of cold fuel(c. 2 tons or more in each) in the wings which causes moist air to form frost. In freezing precipitation, however, it must be de/anti-iced, and is not allowed.
Boeing also suggest using wing anti ice on ground (which heats all but the outer leading edge devices) if engine anti-ice is used for taxi and take off in icing conditions and the plane has not been de iced with type 2 or 4 de icing fluid. Boeing define icing condtions as 10 degrees C or below and visible moisture present or vis below 1 statute mile (1600meters) or contamination on taxiways or runway.