In recent days, I have received a number of calls about tomatoes with rot on the bottom of the
fruit. One of the most common problems in growing tomatoes is the appearance of a water-soaked or slightly sunken dark colored spot near the blossom-end of the fruit. This problem is called blossom-end rot. Blossom-end rot is one of the most common problems in growing tomatoes in Georgia.
The problem appears as a water-soaked spot that darkens and enlarges into a widening circle until the entire tomato begins to rot. The affected area may remain small or it may cover one-third to one-half of the surface. As it gets bigger, the skin shrinks and the surface becomes flattened or sunken, dark and leathery. Once bacteria invades the spot the entire tomato becomes soft.
Blossom-end rot occurs when plants grow quickly during the early part of the season and then are subjected to a period of dry weather when the fruits are still young and green. Abundant rain, on the other hand, may smother the root hairs and cause the rot to occur during sudden hot weather.
A calcium deficiency causes tomato blossom-end rot. To control blossom-end rot, the home gardener will need to take several steps. One will need to start early, even before planting the crop, to prevent this condition.
Steps in controlling blossom-end rot:
* Soil test early in the spring and apply dolomitic lime if needed. This should be done several weeks before planting.
* In gardens where this condition has been severe in past seasons, broadcast five pounds of dolomitic lime per 100 square feet just before planting and plow the ground six to eight inches deep.
* Mulch the plants.
* Apply water to keep soil moist throughout the growing season.
* A calcium spray, first applied when fruits are first visible can help prevent this disorder. Mix four tablespoons of calcium chloride per gallon of water. Spray plants until solution begins to run off the leaves.
For more information, contact the Dawson County Extension Office at (706) 265-2442.