So called 'megablooms' or fused blooms will usually die and fall off. It's because they are malformed, sometimes sterile, and if they do set fruit it is usually malformed as well.

But I'm curious as to what you are basing the belief on that big blooms = big fruit?

Fruit size is genetically determined for the most part although it can also be affected to a degree by growing conditions. Some maintain they can increase the size of an individual fruit by removing all the other fruit that set on that same cluster.

You don't mention the variety involved but if it is beefsteak type size you want then you need to grow beefsteak type variety tomatoes.

Dave

Dave:
I guess I was thinking that tomatoes are like apples. In an apple cluster there often is a "king blossom" that will give you a really big apple. Also some of these big blossoms I am talking about are fused blossoms. That is why I thought a big blossom equalled a big tomato. The variety I am growing is Mega and it is a beefsteak. It is from Canada. Other than that I know nothing of its history but it is beefsteak. I am now wondering what percentage of fused blossoms abort for reasons other than not enough pollen and not getting fertilized? Any idea?

The tomato plants are not getting too much nitrogen. The weather has been good. We have had adequate rainfall. I guess these fused blossoms just hang by a slim thread.

What are your day time high temperatures. Also what are your night time low temperatures. Here in North Alabama if night temps stay above 75f+ and day high temps 95f+ we get very little if any fruit set.

Doitall:

We have been having temperatures up to 80 in the daytime and no lower than 60 degrees at night. Very nice weather for this time of the year for us.

I am now wondering what percentage of fused blossoms abort for reasons other than not enough pollen and not getting fertilized? Any idea?

No real idea because honestly most of us pick them off if we see them since we don't want the fruit they might produce IF they produce fruit. And IME they seldom do.

But keep in mind that we aren't talking typical blossom drop here so it isn't temperature related like blossom drop. With fused blooms the weight of the bloom alone can cause the pedicel to break even if the bloom itself isn't obviously deformed.

Dave

did you say what variety this is? Some are assuming you are seeing fused blooms, but I grow a beefsteak called Beef Heart and it does have large double blooms that are not fused blooms. I feel like this year my bee population is really low, so I have been using my fingers to pollinate and shaking stems a bit. You might want to bring out a little paint brush everyday and pollinate to help them, then see what you get. I also think sometimes the earliest blooms don't set fruit for me, especially on the beefsteaks.
I have one bed with several small tomatoes, but then a couple plants are dropping most of the the blooms. I think they might be getting a bit too much water from the drip system as all my drippers are not consistent.

I have a megabloom on one of my Big Rainbows that is setting fruit; so far it's the only tomato coming on from 2 plants of B.R. I don't care if it's "ugly", as long as it's edible. But now I'm wondering if it will be really worth it (from Digdirt's comment above)? So I'm having second thoughts about letting it grow. If I leave it on there will it impede the plant from producing more tomatoes?

did you say what variety this is? Some are assuming you are seeing fused blooms, but I grow a beefsteak called Beef Heart and it does have large double blooms that are not fused blooms.

Double blooms are fused blooms 99% of the time. The sepals may not be fused so it may not be obvious but the ovules and pedicles usually are so you get a fused malformed fruit if both the blooms set fruit. And the OP did mention fused blooms.

But now I'm wondering if it will be really worth it (from Digdirt's comment above)?

Your choice. They are often terminal growth on that stem and I don't want to prematurely terminate growth. So removing them triggers new growth from the node below it the bloom.

Dave

I have certainly read that fused blooms will create large fruit... but if your goal is large toms regardless of looks then you should expect results. In a joint venture between my brother and I , we started a late season trial on plants that we cant get in our area from seed. I gave him 4 plants and I kept 2 on the trial. He told me he had one with a large blossom bigger than anything he had ever seen. It just so happened we were going to the state fair so I came by his home and saw this bloom and yes I too had not seen a bloom this big before either. As it turned out it was rather malformed but since our thoughts were to go for weight so we didnt care about that. So the weigh-in had impressive results as neither of us had grown a tom this big before.

Vantage thread !

Here is my $0.02

Megabloom might look like a MEGA single bloom but in reality they are a collection of several blooms under one shell. That is why sometimes we see one of them don't get fully pollinated or it is sterile and it rots . Or the parts of the ugly fruit ripens early or late.

Some gardeners would just nip them. I keep them just for the heck of it.

The reason for such blooms are mostly climatic, me thinks, that is, it happens early in the cold spring. But also there is a genetic factor. Some championship varieties, eg, like Big Zack would produce more megablooms than the others , resulting in some ugly huge tomatoes. JMO