Blossom End Rot

A lot of you may be seeing some problems in your garden right now, especially if you are growing tomatoes,  peppers, squash, cucumbers and melon fruits.  One of the most common complaints I hear is fruits, which develop a moist, soft dark spot on the blossom end of the fruit.  Many people believe this to be a fungus or other disease.  On the contrary, this is neither a disease nor insect damage.  These are classic symptoms of blossom end rot and it is a systemic problem brought on by a calcium imbalance within the plant.  Since it is a physiological disorder, we can treat it easily.

No Fungus or Disease

Blossom end rot can happen anytime but is often more prevalent when the growing season begins wet, and the summer turns dry as the fruit is setting.  Fruit will not mature to full size, and many will appear stunted or distorted.  Eventually, dark areas will appear, enlarge, and turn moist.  This area will eventually begin to rot, develop fungus or mold.  Affected fruit should be picked and discarded.

Calcium is the Key

The cause of the problem is a lack of available calcium. Calcium is heavily used by the plant to mature and ripen fruit.  There can be many factors that can cause calcium to be unavailable to the plant.  Lab testing may show that there is calcium in the soil, but the plant cannot uptake it. Several of the most common problems are:

  • Wide fluctuations in soil moisture
  • Excessive nitrogen in the soil
  • Soil pH out of acceptable range
  • Soils high in salts.

Prevention and Treatment

To help prevent and control blossom end rot do the following:

  • Be consistent in your watering patterns.  The moisture level in your soil should be consistent.  Watering on a schedule is not the answer.  Water only when it is needed.  Water slowly to allow moisture to infiltrate deep into the soil.  Mulch your garden beds to help retain the moisture.  I water when I can stick my finger into the second joint, and the soil is dry.
  • Keep your soil rich in available calcium.  There are several products available that can help boost soil calcium organically. Grinding eggshells in your blender and then spreading the finely ground eggshells in your garden will help.  Any product listed as dolomite lime, calcite, or ground oyster shell will do the same trick.
  • Try to keep your soil pH as close to 6.5 as possible.  Adding dolomite lime to your soil can help raise pH if your soil is acidic.  Adding organic matter is the best way to lower your pH if your soil is too alkaline.  Coffee grounds are effective in some cases where soil pH is too high.
  • Stop using chemical-based synthetic fertilizers.  These compounds, especially those with high nitrogen content, can leave excessive nitrogen in the soil, which is not only bad for the soil but can lock up available calcium keeping it from the plants.  Using only organic fertilizers like compost tea is our recommendation.

There have been some reports that adding crushed eggshells to your compost tea as it is brewing and then applying as a foliar spray can be helpful.  There is no research on this that I can find, but it certainly won’t hurt the plant.

Links and Resources

For more information about organic gardening, lifestyles, and living, visit our website at West Texas Organic Gardening.

If you found the information here helpful, you might also find these articles on our website of interest.

Planting your Transplants

Plant Nutrition – Beyond N-P-K

Compost Tea

If you have more specific questions or problems, you can contact us using the contact form on our website. You can also post your question to our community forum at this page; West Texas Organic Gardening Community Forum.

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