The Blob is on My Plum Tree

This is a link to some pictures of "The Blob" (dark brown stuff wrapped around the branches, about a hundred of them, three or four inches long) which has attached itself all over my Italian Prune tree in upstate New York. Does anyone know what this is and what I should do to it?
http://caravelabooks.com/plumcrud /
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On Tue, 14 Jul 2009 15:00:11 -0500, Bert Byfield

Looks like black knot, a fungus.
http://www.ces.ncsu.edu/depts/pp/notes/oldnotes/fd4.htm
Boron
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http://www.nysipm.cornell.edu/factsheets/treefruit/diseases/bk/bk.asp
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