The greater part of the book is, indeed, devoted to the actual and potential use of microorganisms (viruses, bacteria, fungi) for plant disease control;
(The greater part of the book; is indeed; devoted to the actual and potential use of microorganisms) (The greater part of the book; devoted; to the actual and potential use of microorganisms)
The greater part of the book The greater part of the book
is indeed devoted
devoted to the actual and potential use of microorganisms
to the actual and potential use of microorganisms