The latest edition of the Ball Blue Book adds lemon juice to their apple sauce recommendations.  They claim that they found some varieties of apples that were lower in acid than others.  In talking to representatives from Ball at a conference they said they used apples from the store and did their testing in the winter months.  

That said the National Center for Home Food Preservation has not adopted their research so it is still safe to can apple sauce without adding lemon juice.  

I would however suggest you make your apple sauce from fresh apples, not those that have been in storage and avoid making it from over ripe apples.  Apples that are grown in Oregon and picked fresh are high in acid.  

https://nchfp.uga.edu  This is the National Food Preservation Site that makes recommendations we follow.    You can google Apple Sauce on this website and follow their research based directions.  

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Nellie Oehler