Resources for investigating pest problems

[BoesTreeService]

Are there good photo guides to use for the investigation of pest and or disease problems. I have a client with a wooded lot who has over half of thier trees showing far too much dead wood in a sudden manner - ie none last year and now several totally dead trees and over half have a large amount of dead wood. Is there a guide that you can look at to get some ideas as to what is happening to these trees?

 

[elmnut]

Insects that feed on trees and shrubs by W. Johnson, and Diseases of trees and shrubs by Sinclair. Cornell Press

 

[Kneejerk Bombas]

Are these trees Ash by any chance?

 

[alanarbor]

wooded lot with recent construction? or wooded left natural?