Here is what I have on file for BER
Blossom End Rot
Physiological Disorder
Symptoms:
Blossom end rot can affect fruit at all stages of development. The characteristic symptom is a progressive deterioration of the blossom end of the fruit, from a water-soaked appearance to a sunken, black, leathery lesion. While secondary fungal infections may occur, blossom end rot is a physiological disorder caused by calcium deficiency induced by water stress.
Control:
Careful water management practices are a key. Irrigation and/or mulching are important. Application of lime or calcium prior to planting may help. Liquid fertilization using calcium nitrate can be used for small plots.
Blossom-End Rot (BER) – Characterized by a large, leathery brown or black spot on the bottom of the fruit. (Fig. 1). In some cases, internal BER can occur within fruit. It generally occurs on the first fruit cluster. BER is caused by a lack of calcium in the fruit which causes the fruit to die back creating the characteristic spot. What can you do to prevent it? Have your soil tested to make sure calcium is present in adequate amounts. Chances are the calcium level will be fine but if it is not, add limestone (for acid soils with a pH below 6), or gypsum when the soil pH is in the 6 to 7 range. If calcium levels are okay, the next most important control is to maintain optimum soil moisture. When tomatoes experience the slightest bit of drought, BER may result. Using mulches will usually significantly decrease BER as excessive evaporation from soil is reduced. If growing on bare ground, avoid cultivating too close to plants to prevent root damage and the need to maintain deep root development. Varieties will vary in their susceptibility so if you have a problem with a particular variety, choose a new one next year. When side-dressing plants, using a nitrate type fertilizer like calcium nitrate is preferable to ammonium based ones like urea. Finally, don’t bother to use calcium sprays. They are worthless in combating the problem. The same problem can occur on pepper and eggplant.