Blossom-End Rot Disease

Although the disease does not spread from plant to plant, it is dependent on environmental conditions. As a physiological condition, neither fungicides nor insecticides will control this disease. However, environmental conditions can eliminate the condition:

  • Consistent water and calcium intake, and avoiding drought conditions.
  • Do not cultivate close to the roots, since destroying their root systems limits the roots’ ability to supply adequate water and nutrients to the plant resulting in Blossom-End Rot.
  • Excessive soluble salt which causes a decrease in the availability of calcium as salt increases.

Factors that can limit a plant’s ability to absorb calcium required for proper growth include fluctuations in moisture (either too wet or too dry), an excess of nitrogen in the soil, root damage during cultivation, and a soil pH that’s too high or low, or cold soil and soil high in salts.

To reduce risk of Blossom-End Rot:

  • Plant in well-drained, adequately aerated soil.
  • Maintain adequate soil water, at least 1-2 times a week during dry spells to a depth of 6 inches. Tomato plants need about 1.5 inches of water per week when growing fruit.
  • Always ensure the soil is warm enough prior to planting, to reduce nutrient loss.
  • Using fertilizers that are low in nitrogen and high in phosphorous provide the nutrients needed for proper growth. A fertilizer high in superphosphate, such as 4-12-4 or 5-2-50. However, applying too much fertilizer can cause the plant to grow too fast inhibiting the calcium from moving through the plant quickly enough.
  • Watering cones can be used to ensure water reaches the roots.
  • Applying mulch minimizes evaporation and helps maintain consistent soil moisture.