Interesting that the relatively rare Apfel surname and a Texas connection exists between your Apfel and my Apfel. My grandfather is listed on my mother's birth cert. as having been born in one of the Dakotas, but I can't find anything else about him.
Please, if in your search, you should find an Ernest Frederick (aka Fred) Apfel, please let me know. All I know for sure is that he was in Texas for a few years during the time of my mother's (and two siblings) very early childhood.