One of my plants is producing weird growths along the length of its leaves. It’s so messy I had to pull one off to get a decent photo. I am assuming the fasciation is viral? Does anyone know much about it?

Tim DH

It may be viral but most likely not. That bloom cluster is amazing. I've never seen anything like that.

The people growing the giant tomatoes are hoping to get fasciated blooms. By selecting the largest fruit they are using the hereditary factor to increase the size of the fruits. Fasciated stems are produced due to abnormal activity in the growing tip of the plant. Often, an abnormal number of flowers are produced on affected stems. Normal branches may arise from fasciated stems.

Fasciation can be caused by a number of factors, including:
Genetics
Bacterial infection
Mite or insect attack
Chemical or mechanical damage
Viral infection
Frost damage

Wow that is amazing. I've never seen a stem like this - it almost looks like a broccoli raab!

While I have never had a frost during tomato season, I have observed issues with excessive fasciation when the weather is cooler - in the highs 50s and low 60s as daytime highs, with overnights in the high 40s to low 50s. Not just blooms, but triple stems when our springs are cooler than usual.

We tend to have our summer temps August-October, so it happens quite often if I plant out before Memorial Day.