Some gardeners welcome them, and others consider them nuisance.
I’ve always understood them to be result of accidental mutation that can be heritable, and Contest tomato growers do select the largest/heaviest fruits to save seeds from. However, from a cook’s standpoint, these convoluted fruits are often pithy from the multiple fused core, and, because the fused blossoms matured at different times — sometimes not only hours but days apart, and were pollinated and set fruits accordingly — they ripen unevenly to the point that earliest set portion of the fused fruit become overripe and spoiling while the latest set portion is still green.
So, some tomato breeders will select out the tendency to form fused blossoms and fruits, and cull plants that produce fused fruits as well as fruits with a belly button or scarred blossom end, rather than tight and smooth unblemished blossom end. In the following instance, I was asked to save and send back the seeds from the small fruit.
Subject: Applestar's 2014 Tomato Gardens
applestar wrote:Here are a couple of varieties I'm growing this year.
One is a cross from an F3 seed Variegated PL x Striped Big Cheef F3#3
I posted some photos of the fabulous variegated foliage earlier.
I asked to try this one because the fruits were larger than it's siblings.
As you can see, the first fruit was smallish, but subsequent fruits have been getting bigger. There are at least three more that are close to harvest in the SFH Tomato. Garden
This first fruit had a sweetness followed by tangy acid bite that lingered. It had rather thick skin which is not my favorite but the skin did peel off in single pull, which compensates. I'll have to see if the breeder wants the saved seeds back.
Reisetomate/Traveler tomato is an example of intentionally selecting for the fused characteristic though:
Reisetomate Tomato | Baker Creek Heirloom Seeds
https://www.rareseeds.com/reisetomate-tomato/
Also called “Traveler Tomato” (“reise” is German for “travel” or “journey”) for the ability to tear it apart a piece at a time, with no need for a knife.
Apparently, however, fasciated blossoms can also result from other factors — bacterial, viral, and environmental:
FASCIATION IN LYCOPERSICON.I.GENETIC ANALYSIS OF DOMINANCE MODIFICATION
QUENTIN B. ZIELINSKI'
The Blandy Experimental Famz, University of Virginia, Boyce, Virginia Received April 12, 1948
https://www.ncbi.nlm.nih.gov/pmc/articl ... df/405.pdf
One of the most striking effects of fasciation in the tomato is the increase in number of locules in the fruit, so that any investigation of fasciation neces- sarily involves the study of locule number inheritance.
Vegetable Problems in Summer - Abiotic Disorders - Sacramento MGs
https://sacmg.ucanr.edu/Vegetable_Problems_Summer/Abiotic
Tomato - Fasciation
The cause of most fasciations is not understood; some may be genetic and are not infectious, or some may be caused by bacterial or viral infections.
Management
Because the bacterium Rhodococcus fascians is a common cause of infectious fasciation, manage fasciation as if it were a bacterial infection unless information is available indicating another cause. Fasciation bacteria survive on infected plants and debris. They spread in water and may infect through wounds. Control bacterial fasciation primarily through good sanitation and use of pathogen-free plants. To control fasciation due to all likely causes (bacterial and genetic), do not propagate or graft symptomatic plants. If affected plants are not removed, at least prune and dispose of distorted tissue.
Tomato Talk | Chicago Botanic Garden
https://www.chicagobotanic.org/tomatotalk_june27
Why are my tomatoes growing together?
A fasciation of flowers can cause two fruits to fuse and grow together. This phenomenon can occur in many different fruits. Genetics, bacteria, fungal or viral problems, the environment, and herbicide damage can cause the fasciation of plant parts
