Blossom End Rot

Blossom end rot (BER) can be a vexing problem for beginner and experienced gardeners. It is characterized by a sunken brown or black area that develops where the flower was attached to the fruit. Watching the fruits of your labor suddenly start turning black can be very discouraging.

BER is a physiological disorder, a basic disruption of the normal function of the plant, and there are a number of factors that come into play. Because it is a physiological disorder, the use of fungicides or insecticides is of no use.

The basic cause is a lack of calcium or the inability of the plant to take up calcium from the soil. The calcium is needed to develop the fruits and lack of available calcium in rapidly forming fruits causes the breakdown of tissues. The inability of the plant to use calcium can be caused by soil pH, over fertilization, and uneven soil moisture. Soil for tomatoes should have a pH value of 6.5 to 6.7. Adjust soil pH by adding lime as necessary. The use of high nitrogen fertilizers should be avoided. Tomatoes should be mulched to prevent swings in soil moisture, which can lead to other problems as well. Planting tomatoes too early in cold soil can also cause BER.

Control of BER is best done before the problem occurs. By following the above practices, you may avoid the problem. Some advocate application of a calcium chloride solution to the plants, but this is best managed on a commercial scale. Other sources don’t think that the application of calcium chloride helps at all. The home gardener normally does not have access to calcium chloride, other than by buying a 40 lb. bag to get a couple of tablespoons the make the solution. If you do have access to calcium chloride, make the solution at the rate of four tablespoons to a gallon of water. It should be sprayed weekly after the blossoms appear. Be careful not to over apply this solution so that you don’t build up salts in the garden soil. We have found that planting your tomato transplants deeper than what they were growing in the pot helps avoid BER. The plant will develop roots along the buried stem and this seems to help the plant overcome the stress of transplantation.

Blossom end rot can also affect eggplants and peppers for the same reasons as tomatoes.

The good news is that it is usually only the first fruits that are affected. This is because the plants, which are usually transplanted, are trying to establish roots as well as produce fruits. Later in the season when the plants are fully established, the problem goes away.

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