Why didn't Saruman go to the Shire to take the Ring?

[Gordis]

Originally Posted by William Cloud Hicklin

How likely would Sauron have been, really, to be aware of Malbeth's prophecy? Who knew of it, aside from the Wise and the cheftains of the Dunedain? And even if he did, would he have believed it? I'm sure the history of the Third Age was littered with Nostrodamuses, most of whom were spouting rubbish.

No, no - it has nothing to do with Malbeth.

Isildur's Bane was spoken about in a dream that first Faramir, then Boromir had seen in June 3018.
It was a fairly recent dream - and troubling. Sauron learned of these "oracular dream-words", as did Saruman (see UT, Hunt for the Ring). Denethor was troubled enough to send the Captain-General of Gondor to search the answers in the middle of nowhere, and this right after the assault on Osgiliath.

At the moment, Sauron was frantically searching for the Ring - the nazgul were out looking for the Shire and Baggins. It was quite simple to dechipher "Isildur's bane", sign of Doom that is at hand.