Trees can be trimmed in Florida year-round, but the best time to trim live oaks is in the coldest and hottest months of the year.
Beetles that spread a fungus, often called oak wilt, can damage live oaks, or even kill the trees. The most obvious sign of oak wilt is that the area around the leaf vein turns brown will the rest of the leave remains green.
The disease spreads quickly to adjacent trees, and can kill a live oak in the matter of months. The trees do sometimes live for several more years, but once they are infected will eventually die.
The beetles that cause oak wilt are most active in the spring months, and are least active in the coldest months of the year, from November to February, and in the hottest months from June to August.