That's one bread book I don't have... but WILL buy!
The "experts" have differing opinions on the use of fruit to jump-start a starter (some say that the yeast on the fruit is specific to the fruit and will not thrive in a flour/water mixture) but I have to tell you that when I started my Puget Sound beast (which is fermenting on the kitchen counter right now) I used unwashed, carefully inspected Italian plums from the tree in my back yard. They were covered with a white, powdery "bloom" and were very ripe. I have made many starters using just flour and water, but THIS one was active sooner and smells better than any before, so I tend to agree with Ms. Silverton. Some experts will say that it is just the sugar in the fruit giving the yeast more food, but if the flour is plenty of food, why would the sugar make that much difference? I don't have a science lab in my kitchen, so don't know for sure whether the yeast I have captured is from the air or the plums... but I DO know that it is not from the flour because I nuked all the flour I used to start it AND to feed it for over a month.
So, I think the use of fruit with a yeast "bloom" on them certainly helps! JMHO!
~sd aka mots