Hopefully none of you have noticed the signs of blossom end rot which is easily identifiable by the brown, sunken patches on the blossom end of tomatoes. If you have, don’t fear this is one tomato disease that is easily cured and first and foremost easily prevented.
Most commonly blossom end rot is caused by a calcium deficiency in your soil, here in San Diego though we tend to have adequate calcium in our existing soil. So who is to blame? Unfortunately, we are. In San Diego blossom end rot could be prevented and cured if we pay attention to how much and how often we water our plants. If our soil is not evenly moist then the roots have a very hard time pulling in their required nutrients. Therefore, our culprits are dry as a bone and soaking wet soils, two conditions that make it difficult for roots to get what they need.
What to do? You know your soil best and are the only one that can physically feel how moist it is. When you are watering tomatoes remember that they like more water, less often then your other plants. In the heat of the summer I give my plants a deep watering once a week. For those of you in containers or raised beds beware of soggy soils and check your drainage. Often times setting up a drip line at the base of your tomato will be giving the area directly below the plant way too much water on an almost daily basis, ignoring the surrounding soil where the roots have spread.
At home in my raised beds I keep the drip on water hungry squash, watermelon and eggplant, using the hose for infrequent watering.
If you have already noticed the disease pick off the afflicted fruits so that no more energy is spent trying to grow what you cannot eat. Employ new watering tactics as soon as possible and mulch around the tomato plant if your soil is more dry then wet to help hold moisture in.