Plant Pathology Infobytes
May 31, 1996
What's Wrong With My Tomato Fruit?
Dark brown or black blotches on the bottom of tomato fruit is an indication of blossom-end rot, a problem which is currently showing up in many vegetable gardens across Mississippi.
The first symptom of blossom-end rot is a slight discoloration, water-soaked in appearance, occurring at the blossom-end (bottom) of the fruit. This area enlarges rapidly, producing a dark brown or black sunken area. The skin over the affected area becomes dry and leathery.
Blossom-end rot is caused by a shortage of calcium in developing fruit. This may be due to a lack of calcium uptake from the soil or to extreme fluctuations in water supply. Tomato plants growing in soils low in calcium and soils which are alternately wet and dry during fruit development are more likely to show blossom-end rot. This problem also tends to be more severe when plants are over- fertilized with nitrogen fertilizer.
The following control recommendations will reduce the amount of tomato fruit lost to blossom-end rot:
Infobytes newsletter was written by the late Dr. Frank Killebrew, Extension Specialist.