http://www.apsnet.org/pd/

http://ohioline.osu.edu/hyg-fact/3000/index.html

http://www.planetnatural.com/site/plant-diseases.html

http://en.wikipedia.org/wiki/Plant_pathology

http://plant-disease.ippc.orst.edu/

http://en.wikipedia.org/wiki/Lists_of_plant_diseases

http://www.dgsgardening.btinternet.co.uk/disease.htm

http://apsjournals.apsnet.org/loi/pdis

http://www.extension.umn.edu/yardandgarden/diagnostics/

http://www.ghorganics.com/page15.html