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Blossom End Rot

As we start to get into the heat of the summer one of the biggest concerns of home gardeners is that status of their vegetable gardens especially their tomatoes. I get a number of calls every year what is wrong with my tomatoes. And many times it is that pesky blossom-end rot. A common problem for tomatoes although not the only problem this is often an easy problem to fix.

Blossom-end rot can be a serious problem with tomatoes. The main symptom is a dark, sunken water-soaked area at the blossom end of the fruit. This physiological disorder is associated with a low concentration of calcium in the fruit. Blossom-end rot is also induced more often when there is drought stress followed by excessive soil moisture; these fluctuations reduce uptake and movement of available calcium.

To manage blossom-end rot:

  • Maintain the soil pH between 6.2 to 6.8 and supply adequate levels of calcium through applications of dolimitic limestone or gypsum.
  • Avoid drought stress and extreme moisture fluctuations by using mulch and deep, timely irrigation once or twice a week.
  • Avoid overfertilizing plants with high ammoniacal nitrogen fertilizers. Excessive nitrogen can depress the uptake of calcium.
  • Foliar applications of calcium with products such as Blossom End Rot Stop, are only short term fixes and often work poorly because of poor absorption and movement to the fruit area where it is needed. (If you are seeing signs of Blossom-End Rot, this is a fast way to get calcium to the plant.)

The best way to prevent the problem is good preparation; a soil test will give the proper recommendations to make your garden a success. If you are seeing issues this year, the best thing to do is make a good plan for next year with soil samples and proper fertilization. With additional questions feel free to call the County Extension Office.