There is one intriguing possibility that might supply a possible treatment for FMD. Aspirin. Salicylic acid (aspirin) is produced by plants in response to infection by pathogens and activates the plant's innate immune system. It has been demonstrated that treatment with salicylic acid can prevent or limit several plant infectious diseases.
http://segenetica.es/cng2/cng2008/biblio/Ref-Marc-Valls---Jones-and-Dangl-Nat06.pdf
http://igitur-archive.library.uu.nl/bio/2009-0512-200821/NatChemBiol-Pieterse-2009.pdf
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Two of my 3 Sicilian Black Italian cuttings are doing well and showing little, if any, sign of FMD. However, one started showing significant FMD several weeks ago. It had been doing well but slowed up as the FMD appeared. I do a foliar spray of worm casting tea that contains salicylic acid on my tomatoes roughly every week. So, I decided to spray the fig too. After 2 sprayings, the leaves have greened considerably and the mottling is clearly decreased. How much of that is due to the aspirin or nutrition from the worm casting tea or both I can not say.