The US Forest Service has made available these informative leaflets on forest insects and diseases. Users may browse the Master Directory by species common name or select the Western or Eastern directories. More than 170 leaflets are listed, from Mountain Pine Beetle to Two-lined Chestnut Borer; note that a few leaflets are available only in [.pdf] format, and not all are available online. Online...

The Department of Plant Pathology at Cornell University provides this online guide to vegetable diseases. A compilation of vegetable disease fact sheets, the site is organized by crop and offers photographic images and a description of each vegetable crop in healthy and diseased states. The site also includes an Online Glossary of Technical Terms in Plant Pathology and links to additional...