Blossoms falling off, blackened

by Mike
(Auburn, CA)

Q. I just planted my tomatoes, so this is a preventative question. Last year I had a problem with blossoms turning black on the stem right beneath the flower and then falling off. What can I do to avoid this this year as my plants mature?

A. From your description, it sounds like the culprit is bacterial speck. As the name implies, it's caused by bacteria (Pseudomonas syringae pv. tomato) that can overwinter in the soil or transmit on seeds. Bacterial speck can appear on any plant part. It thrives in cool weather, so if you had a wet spring last year, those bacteria were loving life on your tomato plants.

Leaves on infected plants will also (eventually) show brown or black irregular spots surrounded by yellow halos.

You can control bacterial speck by avoiding excessive watering. Naturally, you can't control the rain! Also, begin a systematic spraying program using a copper spray. Apply each week and after rain.

Take these additional measures to minimize the risk of tomato blossom drop.

Good luck and happy gardening!
Your friends at Tomato Dirt

Comments for Blossoms falling off, blackened

Average Rating starstarstarstarstar

Click here to add your own comments

Oct 27, 2015
Informative NEW
by: Harris

Bacterial speck is a serious problem, and one you can’t use water to treat. They using specific chemicals like copper spray to stop the stem turning black. As long as you do this right, it should top the fruit falling off. catalina hotel

Jun 28, 2015
bacterial speck NEW
by: staicy

I have heard about this bacterial speck. When my plants are affected with the same defect, I called an agricultural officer. He told me the same thing that you have explained here. Actually these things have to be taken seriously.senior living vancouver wa

Click here to add your own comments

Join in and write your own page! It's easy to do. How? Simply click here to return to Tomato Problems.

FREE! 10 Must-Know Tomato Growing Tips: 20-page guide
Get yours here: