Blossom end rot is the scourge found afflicting many tomato, pepper and watermelon fruits growing in home gardens. This affliction first appears as a sunken, dark or black spot on the blossom end of the fruit.
The term blossom end rot is somewhat misleading because this disorder by itself does not cause the fruit to rot. Once developed, the tissue afflicted with this condition can allow other rot-forming bacteria and fungi to attack and rot the fruit.
Home gardeners can stop this condition from ever occurring. Focus on preventing rather than curing this disorder. Once your half-grown tomatoes and pepper fruit have started to drop off the plant with black spots on the end of the fruit, it is too late. Prevention must start even before you plant the crop and must continue until the last fruits are harvested.
Blossom end rot is caused by a lack of calcium in the cell tissue. Calcium is not transferred from the older tissue to the newer tissue in tomato plants. So when there is not enough calcium present in the new tomato fruit, it cannot be supplied from other parts of the plant.
The lack of sufficient calcium causes the tissue to die and turn dark. The best way to prevent this shortage of calcium is to follow these steps of prevention. If you skip or procrastinate on any of these steps, blossom end rot can occur:
Before you plant, soil test the area where you are going to plant your garden. Adjust soil pH to between 6.0 and 6.5. Apply dolomitic lime early in the season if recommended on the soil test report.
Mix one cup of dolomitic lime for each plant during the transplant operation. This should be mixed thoroughly with the soil going back in the hole around the plant.
Use three to four inches of organic mulch around each plant.
Water plants on a regular schedule during dry weather. Try to keep soil uniformly moist but not soggy.
Spray each plant with a calcium spray when the first tomato is about the size of a quarter. This calcium spray can be found at feed and seed dealers, nurseries and good garden centers. Spray plants until the solution begins to drip off the leaves. Repeat this spray procedure according to the label on the bottle.
For gardeners who grow tomatoes in containers, apply two cups of lime per five-gallon bucket of soil. And spray the calcium solution also.