I'm suuuuuuure I'll get reamed for having too much time on my hands...in the recent peach controversy on our NG some believed the Mackinaw was fake and many others thought they'd heard of it. I emailed Dole and here was their response:
Dear Dole Consumer:
Thank you for contacting Dole. We contacted our Fresh Fruit experts for information regarding the Mackinaw Peach.
The Mackinaw Peach is not commercially grown by Dole. It is possible that it is grown in another part of the US as the southeast has some of their own varieties. Each area is slightly different and there are many varieties that are developed for the particular climatic characteristics of a specific area. At the present time, Dole does not market this variety of peach. We're glad to provide the information you requested and hope it is helpful.
Sincerely,
Consumer Response Staff Consumer Center Dole Food Company, Inc.
[Zup] Uh, I guess that means it probably doesn't exist, but Dole admits that they really don't know...sheesh.