Blossom end rot

If some of your tomatoes have a black spot on the bottom, chances are they've come down with blossom end rot. This condition isn't something to be overly concerned about since it's not caused by a virus, bacterium, or fungus and won't travel beyond the fruit in question.

Technically, blossom end rot is caused by lack of calcium, but that doesn't necessarily mean your soil is low on the essential micronutrient. A variety of other factors can reduce your plants' ability to take up calcium, including drought, damage to the plant's root system, excessive heat, or even rapid plant growth.

I'm not as careful as I could be about making sure my tomatoes always have an even supply of water, so I often find a fruit here and there that has succumbed to blossom end rot. The affected plants are most common at the beginning of the season, and are more prevalent in certain varieties than in others. If blossom end rot seemed to be excessively widespread in your garden, you should mulch your tomatoes to maintain an even supply of water in the soil and should take care not to overfertilize. Otherwise, just cut out the spot and enjoy your homegrown tomatoes.

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This post is part of our Minor Tomato Ailments lunchtime series. Read all of the entries: