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Blossom End Rot Sprays

Blossom end rot is a disappointing sight for a gardener who has worked hard to get those tasty vine grown tomatoes. Blossom end rot is a sunken watery brown rot on the bottom of the fruit, and while the unaffected part of the tomato is still edible, most gardeners just throw the diseased fruit away. Fruits showing the disease cannot be treated, but treatment can prevent rot on future fruits.
  1. Causes of Blossom End Rot

    • Blossom end rot is a disease caused by calcium deficiency. Often the lack of calcium has more to do with a lack of steady water supply than lack of calcium in the soil. It's most prevalent in plants with uneven soil moisture, which can be caused either by uneven irrigation or climate conditions that are uneven, such as dry periods followed by wet rainy periods.

    Other Plants Affected

    • Tomatoes aren't the only fruits affected. Peppers, cucumbers, melons and eggplants are also susceptible. The disease does not pass from plant to plant, but many plants can be affected by it at once and most can be treated with the same methods. Be sure to read the chemical label for a list of plants that can be treated.

    Commercially Available Treatments

    • There are several commercially available treatments, all having calcium chloride as the active ingredient. Green Light Blossom End Rot Spray, Bonide Rot Stop, Enz Rot Blossom End Rot Concentrate Spray and Ferti-lome Yield Booster are some brand-name sprays found in garden centers and online. Always follow label directions.

    Do-it-Yourself Treatments

    • A simple home mixture of four teaspoons of 96 percent calcium chloride to a gallon of water can be effective. Calcium chloride can be found in most hardware or home and garden stores, but it usually comes in 40- to 50-pound bags. It has other household uses, but 50 pounds isn't necessary for gardening.


    • There are some ways to avoid the need for blossom end rot sprays. Don't set tomato plants out too early; make sure the soil is warm enough. Provide even moisture to the soil; mulch beds for better soil retention. Apply lime to the soil two to four months before planting to sweeten the soil and provide calcium.