Blossoms falling off.

[Plumbob]

My tomato plant blossoms grow beautifully and then the stem forms a ring around it and the blossom falls off. I've had this problem before in different areas of the country and with the use of blossom (or bloom) set I've been able to avoid this happening. I've tried the same technique here in Dallas, Tx and it hasn't worked. Does anyone know of another method that will prevent blossom fall-off?

[gixxerific]

Read this https://www.helpfulgardener.com/forum/viewtopic.php?t=14764

[rainbowgardener]

There's a whole STICKY at the top of the tomato section about blossom drop. Basically you need to try to correct whatever the condition is that is stressing the plant.