One grower posting here (I do not remember exactly who) said
that Granny Cantrell was the only heirloom not showing any
root-knot nematode damage in his garden:
http://t.tatianastomatobase.com:88/w...b=General_Info
You might try it and verify that for yourself if looking for
heirloom flavor in RKN country (and if it is not too late
ripening for your growing season).