University of Florida specialists now (as of February 1, 2010) recommend that fronds that have turned brown due to the cold temperatures be left on the palm. It is thought that these dead fronds may help to protect the terminal bud of the palm from damage if more cold temperatures are experienced. It is especially important to allow fronds with any green tissue, however minimal, to remain on the palm, since these green areas manufacture food for the palm by photosynthesis. 

Copper fungicide can be applied to the bud area to help prevent bud rot diseases. Ten days later a second application of the copper fungicide can be made or a broad spectrum fungicide can be substituted. If the spear leaf easily pulls out, clean out the decayed tissue as well as possible and direct the copper fungicide into the remaining opening. 

See the complete fact sheet, Treating Cold-Damaged Palms, for additional information: http://edis.ifas.ufl.edu/mg318
Additional comments can be found here: http://okeechobee.ifas.ufl.edu/PalmColdDamageJan2010.pdf