What are you fertilizing with? When you feed a tomato plant a fertilizer that has too much nitrogen in it, you get foliage at the expense of flowers.

There's no need to cut off "side shoots" (aka "suckers"). I was brought up to do just that, but I soon realized that the only thing it was accomplishing was to reduce the number of tomatoes I got: an important issue in dry summers when we lost most of the lower tomatoes to thirsty wildlife or to severe, moldy cracks.

Now I let the first suckers grow and only remove the later suckers if it looks like the plant will get so thick I won't be able to monitor the center of the plant for hornworms or disease (there's more likelihood of fungal disease in humid or wet situations if the foliage gets too thick).

yumtomatoes is right that you may have over-fertilized. Here's my epic basics-of-fertilizer-and-dangers-of-excess-nitrogen post from another thread:
It's the huge 9th post -- can't miss it.

Another possible explanation is the planting location: how many hours of sun does the plant receive? Tomatoes should have at least 6 hours of direct sunlight. However, there's a guy in Minnesota who used to post here who had great luck with tomatoes which didn't get that much direct sun; I suspect he had what's called "bright shade."

I meant to mention the issue of hot weather. Tomato blossoms can't be fertilized if daytime temps are over 90-95 and overnight temps are above 75.

Cherries (including grapes, currants, etc.) generally handle high temps better than large-fruited types.

Another thing to bear in mind is that determinate tomatoes should not be pruned (suckered) because you will remove the fruit producing branches if you do that.

Betsy

Tomato blossoms can't be fertilized if daytime temps are over 90-95 and overnight temps are above 75.

This refers to pollination rather than adding fertilizer. Pollination fails -- i.e. there can be no fruit -- in particularly hot weather.

Sorry to be so unclear.

If you remove the suckers the fruits will get bigger.

If you remove the suckers the fruits will get bigger.

Sorry but that is mostly myth. Fruit size is genetically determined.

Dave

" 'If you remove the suckers the fruits will get bigger.'

Sorry but that is mostly myth. Fruit size is genetically determined."

Is there any scientific data disproving this?

IIRC, people who are trying to win a Largest Tomato contest do some pruning, but I can't remember if they prune branches or only flowers.

For those of us who are looking for edibles rather than a single prize-winner, it's a case of which would we rather have: five beefsteaks that average 16 oz. ... or a dozen that average 15 oz.? (Sorry, yum: that's a totally unscientific estimate.)

The largest fruit in my garden so far is a super-wide, somewhat V-shaped beefsteak on my German Queen. The shape is a dead giveaway that it resulted from an abnormal bloom (fused blossom, megabloom, whatever) -- as many large beefsteaks do. No catfacing: it's a real beauty. As it happens, that tomato's not growing on the main stem. If I'd removed that sucker branch, I wouldn't have had that particular blossom.

I don't care how large or small my Romas are -- I'm looking for the greatest yield per plant, which is definitely not going to happen if I start pruning branches off! I have three Romas from Bonnie, purchased a few weeks apart. The ripe fruit on the older plant are much larger than the ripe fruit on the younger plant. I assume that planting time was a factor, or perhaps the weather. (The other younger plant had an accident and has no ripe fruit yet.)

"For those of us who are looking for edibles rather than a single prize-winner, it's a case of which would we rather have: five beefsteaks that average 16 oz. ... or a dozen that average 15 oz.? "

Well if the difference is only 1 oz, I can see that not mattering. But what I care about is that I get a decent size tomato if it is a beefsteak. So what would I rather have - 5, 16 oz fruits or 10, 8oz fruits? I would rather have 5, 16 oz fruits because I don't like a lot of skin and large fruits have a lower skin to inside ratio.

Is there any scientific data disproving this?

Disproving what? Science doesn't DISprove, it either proves or fails to prove.

Science has proven that one's genetics, one's DNA (be it tomato DNA or people DNA) determines characteristics like eye and skin color as well as tomato color, height, tomato leaf shape, tomato color, tomato plant and fruit size, # of locular cavities, etc.?

And yes there are ample scientific studies done that show that any increase in tomato fruit size on plants which have been heavily sucker-pruned when compared to plants that have NOT been sucker pruned is minimal, if any. Further that that increased size, if it occurs, could just as easily be attributed to growing conditions as to any pruning done.

In other words science has proven that the old myth that 'suckers' suck energy from the plant is just that - a myth. The photosynthesis energy gained from the leaves on those 'suckers' actually provides additional energy to the plant.

As already mentioned, depending on growing conditions, removing all but 1 of the blooms from a cluster of blooms 'may' slightly increase the size of the fruit that develops from the remaining bloom. But any increase in size is still limited by the genetics of the variety used. A cherry plant will not produce a 6-8 oz. fruit no matter what you do and a Roma won't produce a 1 lb. roma tomato.

Dave

"Disproving what? Science doesn't DISprove, it either proves or fails to prove."

I disagree. What the data from properly designed randomized, controlled studies can tell you is whether to reject the null hypothesis. Rejecting the null hypothesis is synonymous with disproving the null hypothesis.

As far as what I was asking above, I will rephrase it for clarity's sake. I was asking whether or not there is any scientific evidence supporting the belief that pruning does not lead to larger fruit. There sure are a lot of people who believe it does lead to larger fruit.

Of course, just because lots of people believe something doesn't mean it is true. That is why I was asking if there is any scientific evidence.

My garden buddy prunes. I don't. He always gets better tomatoes, but his place is in a better location and my greenhouse is too shady. I keep telling him to try leaving one alone some season and I'll try pruning. But old habits die hard and we both can't stop following our old methods.

It's a simple enough experiment to try yourself and answer the question in your particular garden.

-Ed