Thanks to the internet, I was quickly able to diagnose my tomato problem as blossom end rot. However, most of what I saw on my google search was advice on how to PREVENT it. I need advice on how to stop it mid-season.
Thanks in advance.
You have most likely read about the cause: inconsistent watering and fluctuating temperatures. Most varieties will grow out of the problem as the year progresses and rainfall and temps stabilize. Some varieties are more prone to BER than others but they also should be OK on the next batch of fruits. As you read, additions to the soil will not stop BER. Time is the best healer. Good Luck.
Some varieties are more prone to it than others. SIP containers eliminate the problem of uneven watering as long as you keep the reservoir full. Select heat tolerant varieties, they do better and have fewer problems with blossom end rot. Smaller tomatoes also have fewer issues with blossom end rot. If you live in a hot place, shading can help.
Happy gardening in Hawaii. Gardens are where people grow.
The reason it can only be prevented is that BER occurs because of the conditions that prevailed when the fruit was set. Once that happens, that fruit is doomed. However, that has nothing to do with what will happen when the next fruit is set, so you just need to change the conditions so that all the future fruit to set will be OK.