The Internet's Finest Tropical Fruit Discussion Forum!"All discussion content within the forum reflects the views of the individual participants and does not necessarily represent the views held by the Tropical Fruit Forum as an organization."
I am not sure amout the cold hardiness of citrus mac. It is related to papeda and is thought to have come from the Philippines. I think that FD and Std poncirus are more cold hardy than Mac. I would group it with Carrizo & Troyer as to hardiness. I do not know of anyone that uses it here. From what I know about it (not a lot) it was used for lemon rootstock by some. I grow lemon on its own roots so have not tried it. Perhaps someone that does use it will have more detailed information. I think it is a receptical for tristeza virus.
I think you will have a hard time with Macrophylla in Savannah. Macrophylla is normally used as a root stock for lemons, and seldom grown for the tree itself. The University of California states, trees on Macrophylla have poor freeze tolerance, much worse that that of trees on any other commonly used rootstock.
These two cultivars are like antiquities in a sense. They have been used in various places and for the most part unknown for most of citrus producers. There are so much BETTER rootstocks available now. In your zone, (8b) I would go to poncirus for rootstock. It is easy to come by, disease resistant, cold hardy as rootstock gets and gets along with lots of soil types. It is compatible with most citrus is easy to graft to. Why would you consider these two odd ones as rootstock?
Can this grow in zone 8b Savannah GA?