Answer: Blossom-end rot of tomatoes is a physiological disorder caused by a lack of sufficient calcium in the blossom end of the fruit. This disorder results in the decay of tomato fruits on their blossom end. Dry brown or tan areas the size of a dime, that grow to the size of a half dollar, characterize this disorder. This disorder is usually most severe following extremes in soil moisture (either too dry or too wet). So, try to keep the soil consistently moist but not soggy wet. An organic mulch over the soil surface will help. You might also try spraying the plants with a calcium solution at the rate of 4 lb of calcium nitrate or calcium chloride per 100 gal of water (or 4 level Tbs per gal of water). This spray should be applied 2 to 3 times a week, beginning at the time the second fruit clusters bloom. Chelated calcium solutions also provide an excellent source of calcium. When using these chelates, follow label directions. Several foliar spray materials containing calcium are available and all work well for tomatoes. Usually only the first tomatoes of the season are affected by blossom end rot so you should still have a bountiful harvest.
Best wishes with your tomatoes!
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