What can I do to control blossom end rot in my tomatoes?
Blossom end rot is a nasty black patch that can show up on the bottom of green or ripening tomatoes. It's one of those gardening problems that can easily be controlled by correcting the environmental imbalance that gives rise to it. That's because it isn't caused by a disease but rather by a calcium deficiency that's created when watering is inconsistent while the fruit is forming.
The ongoing drought has set up the perfect circumstances for blossom end rot since many of us don't have the time or energy to keep the ground evenly moist. Tomato plants respond to the resulting fluctuations in moisture levels by diverting water and nutrients, including calcium, away from fruit production and channelling them instead into leaf production.
There's nothing you can do that will save any tomatoes that are already affected by blossom end rot, so you might as well compost them and concentrate instead on turning things around so that later crops won't be affected.
The way you fix the problem, as you've already guessed, is to keep your tomatoes evenly moist despite the lack of rainfall. That's easier to do if you mulch your plants and irrigate your garden either in the early morning or in the evening when the water will stick around long enough to do your plants some good.
In some cases, a calcium deficiency can also be caused by rapid plant growth. Excessive nitrogen is usually to blame for this and although it isn't generally a problem if you use fish fertilizer or condition your soil with compost, it can be one if you use chemical fertilizers that are high in nitrogen. Cut back on those and you'll be back in business in no time.
If you have any questions or comments, please send them to me at vanessa@gardenmuse.ca.
Originally published in the Creston Valley Advance on July 17, 2008.
