Hi Steve,

Thank you for contacting the UNH Extension Yard and Garden Infoline with your request for additional information about how best to treat your apple tree for apple magot.  It is important to monitor your tree using traps to determine if and when your tree may have maggots. I have included links to fact sheets that discuss the problem.

https://scholars.unh.edu/cgi/viewcontent.cgi?article=2091&context=extension

https://extension.unh.edu/sites/default/files/migrated_unmanaged_files/Resource005256_Rep7402.pdf  This link includes a spray schedule for pests.  The information notes, "Sevin is registered for all of the listed crops. It is effective for many pests, including apple and blueberry maggots, Japanese beetles, spittlebugs and tent caterpillars." A footnote to the spray schedule for apple maggots notes, "Add carbaryl (Sevin) to mix. Treat with Sevin at the frequency stated on the label, starting when adults appear on traps. Stop when no more maggot flies are trapped." 

https://extension.umn.edu/yard-and-garden-insects/apple-maggot  This fact sheet includes descriptions of traps that can be used to monitor for maggots.

https://extension.psu.edu/apple-maggot-in-the-home-fruit-planting

I have searched for information about using smokers for treating apple maggots in orchards and have found no information about that method of treatment.

Please contact the Infoline again if you have further questions.