There are many things that look like a disease, or insect damage, but they are not! What are they called? These are "abiotic" disorders, and they get their name from being "non-living" causes of plants stress and yield reduction. Cold snaps, heat stress, wind, hail, low spots, and pH and nutrient levels in soil and water are common causes for abiotic disorders, and Becky Sideman is here from the University of New Hampshire Extension to talk out some of the common and tricky ones with us!

Here is Becky's factsheet on Blossom End Rot.
Here is Becky's video about Yellow Shoulders management. 
Here are the American Phytopathological Society Compendia that detail disorders in addition to diseases and insects. They are now available for free as pdfs!