Steve Earle has made 19 albums of country, rock, folk and blues. Each of those albums has some sort of thematic title. Only two had the name of loved ones as the title: his tributes to mentors Townes Van Zandt and Guy Clark. The new “J.T.” is a different sort of tribute, Earle covering songs written by his son, Justin Townes Earle, who died at 38 last year. The readings are reverent and emotional. Earle will likely draw from that album as well as his own 35-year recording career.