San Antonio Property Inspector Joe Barnett with Bumblebee Home Inspection

Recommends trimming oaks between the 4th of July and February 1.  One additional note about the pruning time is in reference to oak wilt; a devastating disease of oak trees that is especially prevalent in Central Texas but has reached other areas of the state as well. The beetle that spreads oak wilt and the infectious fungal mats on which the beetles feed are most active in spring but may be active in most months of the year. If you prune oaks when beetles and fungal mat infections are active you are inviting these disease-carrying beetles to come and infect your tree.
Thus pruning of oaks is best kept to the coldest months or if absolutely necessary, the hottest months in order to avoid inviting trouble. It is also important to paint pruning cuts on oak immediately (not hours later) with a commercial pruning sealant to repel the beetles.