August 11, 2013
blossom end rot
The first set of ripe tomatoes we've gotten have all had black or brown spots on their bottoms, which looks like blossom end rot. Anna from The Walden Effect, explains that it isn't caused by a virus, bacterium, or fungus, but rather by calcium deficiency. This doesn't necessary mean you need to go crush up some eggshells by your tomato plants; Anna explains that a range of factors, from drought, root damage, excessive heat, or even fast plant growth, can lead to calcium deficiency.
Luckily, blossom end rot is most common on early season tomatoes, and, as we've noticed in our garden, the problem diminishes with subsequent sets of ripening tomatoes. If the spot is small, you can simply cut it off and enjoy the rest of the tomato.