I get lots of questions on email and Facebook posts like this: “Randy, what’s happening to my tomatoes? Is this a disease or an insect problem? And how can I fix it?”
It’s affectionately known as Blossom End Rot, and it’s neither a disease nor a pest problem. It’s actually a cultural care problem, or otherwise known as a physiological. In other words, Blossom End Rot is the sign of a calcium deficiency in the soil. And because of that lack of calcium, it makes the problem very fixable. Another bit of good news is that any vegetable that is suffering from BER, is still edible after you cut off the bottom part that is ‘rotted.’
While BER seems to be most commonly targeted to tomatoes, it can show up on a wide array of cucurbit crops such squash, zucchini and cucumbers. You know you have BER on both green and red fruit when and where they develop a black, dry rot area on the very bottom or base of the fruit. And on tomatoes it normally happens on the medium to larger sized varieties. But it’s also worth noting that BER can appear on fruits at any time in their development, but most commonly appears when fruits are one-third to one-half grown. The initial symptoms are water-soaked spots on the blossom end of the fruit. These spots later enlarge and become black. Secondary infection by other decay causing organisms usually follows.
Okay, so now how can the calcium deficiency be ‘fixed’ as noted earlier. First, you the watering/irrigation needs to be extremely consistent. Extreme fluctuations in moisture is the first culprit – too much, then not enough is what leaches out the calcium first and foremost. There are plenty of calcium products on the market, such as calcium chloride. We’ve also discovered that using trace mineral packages such as Azomite can help re-mineralize that need as well.
If you think your watering is consistent and you believe you’ve added the appropriate trace minerals, the other things that can introduce BER are root pruning and excessive nitrogen fertilization. Stop doing those two things and you can resolve the BER situation as well.
And, just as a reminder, and especially on tomatoes – BER does not mean you have to throw the fruit away. Cut off the rotted portion and you can still enjoy the fruit.