Persimmon is in the ebony family, and used to be used for golf driver heads before they got the fancy metal ones. As for spalting, check out Seri Robinson, aka Dr. Spalt. Mostly it takes about 6 months, and some moisture in the wood. Not sure if it is possible for dried wood to be wet up again to the point where it can spalt or not. Much more than 6 months and it gets too soft since spalting is the first step in rotting. Some woods spalt more easily than others.
robo hippy