Blossom end rot, a common tomato disease, can become a problem if there’s insufficient calcium in the soil. Photo by Lynn Ketchum.
Blossom end rot, a common tomato disease, can become a problem if there’s insufficient calcium in the soil. Photo by Lynn Ketchum.

 I am getting a lot of calls about tomatoes that are big and beautiful, but get a black spot.  That black spot starts on the blossom end of the tomato and travels toward the stem end.  Lightly infected plants have a few black spots.  Heavily infected plants turn into black mush.

Tomatoes Are Vulnerable

Blossom end rot is not unique to tomatoes, but it causes more trouble in tomatoes.  Basically, it is an electorate imbalance involving calcium.  Before you run out and get some calcium for your tomatoes, though, you should know it won’t help.  Tomatoes need a constant supply of calcium to grow properly.  When the tomato plant is growing, it may take all the available calcium and leave none for the tomato.  This is usually the problem with early tomatoes that get blossom end rot.

Inconsitant Soil Moisture

Plants can only absorb calcium through their roots.  It comes from the water the plant absorbs.  Drought can make it impossible for the plant to absorb enough calcium to keep the tomato in calcium until it is ripe.  Keep the soil moist but not soggy to make sure your plants can absorb the calcium they need through the roots.

Destroy Tomatoes Who Are Infected

There is no cure for blossom end rot one it starts.  It is important to pick the tomatoes with problems and trash them as soon as you see them.  This helps keep the problem from spreading.  There are two other things you can do about this problem. 

Prevent Blossom End Rot

Use a soaker hose or drip irrigation to water so you do not splash soil on your tomatoes.  Put three inches of mulch around your tomatoes.  This keeps them from touching the ground, but also serves to keep soil from splashing up.  Mulch also conserves water.  Make sure there is enough space between your plants so that air and sunlight can penetrate.  Follow these suggestions and you should have minimal problems with blossom end rot.

 

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