MSU Extension:
Blossom end rot is a physiological problem usually associated with tomatoes. Many gardeners have seen it, but may not know why it happened. Michigan State University Extension horticulture educators and Master Gardener hotlines receive a number of calls as gardeners begin circling their gardens looking for ripe produce.
Tomatoes, being the biggest garden diva, are alarmed and shocked at many situations that other less neurotic vegetables ignore. Tiny doses of herbicide, blowing sand and lack of water will produce damage to tomatoes while other vegetables tough it out. But other plants, if stressed enough, can also experience blossom end rot. These are peppers, eggplant, summer squashes and melons.