I'm trying to track down a species of Ficus from Australia that reportedly makes an excellent nematode-resistant rootstock for figs.
I found it described in an article from the Florida State Horticultural Society from 1925. They tested 18 Ficus species as potential nematode-resistant rootstocks for figs, and found that the most promising was an unidentified Ficus species from North Queensland, Australia, introduced by the Office of Seed and Plant Introduction in 1921 under the name SPI 52406. Growing in its native habitat, this species was described as, "A large clean tree with fruit of fine delicate sweet flavor and size of a black Smyrna fig, only more rounded and dark crimson when ripe." They report that the species is evergreen, and in Florida it suffered foliage burn at 29 degrees F, and die-back at 25 degrees F.
They report that fig scions made graft unions more reliably and with better subsequent growth on this species than grafted onto Ficus glomerata, their second-best choice. They report that they planted out one fig grafted onto Ficus 52406 in spring in nematode-infested soil, and as a control also planted a self-rooted fig 17 feet away. By fall, the grafted plant had ripened almost a hundred figs, growing to 4.5 feet with a 2.5 inch diameter trunk just above the bud union. The self-rooted fig nearby suffered heavy nematode damage to its roots, grew to just 2.5 feet, and ripened only a single fig the same year.
I can't find any subsequent information on this species.
I know this is not a lot of information to go on in terms of the description of the mystery Ficus 52406 from North Queensland. I've read that there are 45 Ficus species native to Australia. But I thought it was worth a shot posting this, to see if anyone might recognize what species Ficus 52406 might be, particularly some of the Australian readers of the forum. Any ideas?
-Craig
(original 1925 report:
http://fshs.org/proceedings-o/1925-vol-38/92-97_Mowry.pdf)