It certainly improves the size. That is well documented. It also increases the earliness.

If a certain pruning technique altered temperature and balanced out how sugars gut used/deposited than I could see how that could effect taste.

I've never seen much advantage to pruning other than maybe getting more plants in a smaller space and maybe a hair earlier first tomatoe, but at the cost of overall production in both number of tomatoes and length of harvest.

Size? To a degree for some of the fruit at least but less overall production. Taste? No effect IMO. Any benefits are certainly not enough of a difference in either to warrant all the work associated with pruning not to mention the lost production.

Dave

Pruning is an art. Getting it right strikes a balance of foliage and fruit. Prune the lower foliage. Limiting main stems to 2, 3, or 4 can increase size while overall production manageable. The support means offers advantages over sprawling in ventilation, disease and pest control and environmental damage (wind and heavy rain). My preference is the trellis method with overhead support of main stems at points below the blossom clusters.

The ability to work around the plants lower sections is easier with pruning. The mulching is easier and there is more working space for companion plantings.

Topping a plant may limit vertical growth but also restricts nutrient flow if too much removed. Remember that the upper leaves protect the fruit from the sun. Some varieties are very prone to scald. Upper pruning may restrict nutrient flow and lead to blossom-end-rot.

There is much more to pruning than the pinching and cutting. Attention to watering and soil are important. Prune dry plants or invite disease. Mulch plants later in the spring to allow the soil to warm.

Look for more local data on varieties and pruning impact.

Here is a link that might be useful: Tomato support & pruning

Unless one grows on the ground, there usually little if any statistical difference between pruning and not pruning in the total yield weight between the same system for growing.

The research has found: pruned plants produce earlier. The individual fruits that pruned plants produce tend to be larger fruits than those not pruned with the same system.

Another way to say that is that unpruned plants produce more but smaller fruit. Pruned plants produce fewer but larger fruits (sooner). However, the total yield difference between the two ends usually ends up being the same (controlled studies taken on numerous plants rather than 1 or 2 in a backyard).

Since most market growers get better prices with larger fruits and hitting the market earlier, pruning can be worth the labor.

Since the current research is indicating that temperature seems to have more of an influence on taste than other environmental factors such as light (the previous thinking) and soil, then it could be that pruned plants, with less shading and thus potentially higher temps, might produce a flavor difference. I just haven't seen anything in the research backing that idea. It is just a probability.

I'd bet that thinning fruit would make the remaining tomatoes bigger and tastier, since each would be fed by more leaves.

I also think that having fairly fat tomato cages gives better results, since the leaves can get more sun and air.

We grow dozens of tomato plants, but the ones in our high-tunnel are pruned to two main stems and are continually pruned when suckers start.

The tomatoes tend to be much larger and ripen earlier (may be due to planting earlier in a protected environment, though)

We get ripe tomatoes starting in mid-July here in NH in the high tunnels but late August in the field. The field-grown ones are supported using re-bar and baling twine weaved from the re-bar to the plants and so on. Works like a charm . . . however, you end up with "Walls of Tomato Plants" . . . which is neat in itself.

We'll continue to use both methods since we like early tomatoes, not only for eating but for the Farmers' Market!

my experince is quite like Mulio's

one more advantage is easier harvest.

an example is last year i pruned and trellised my opalka tomatoes to one ore two main branches and i got way better production and up to 1 pound fruit. this year i got ill and didn't get to them. the result was much less fruit and smaller fruit.

well that is just two different years look at things.

i do prune suckers with vengeance. i am sure that directs the plants energy into the fruit as that is how it reproduces it's self.

the best way to decide is to try it your self and see if the work is worth it.

another benefit is a neater garden and you can plnat more in less space.

the way i look at it is seed is cheep and with trellises i can plant more plants in less space that results in more and bigger fruit at an earlier date.

i live in zone 4 so we have to work to get good production.

Dean

To me it's..."If you want the NFL....GO to the NFL". Or, if you want big tomatoes....GROW the big tomatoes! Like Big Zac, Porterhouse, etc. You can prune a Stupice all ways but Sunday's and you still have a ping pong ball. Sure you might get a slightly larger ping pong ball by 5% but it's still a ping pong ball. I don't prune a single healthy branch and have mostly huge healthy plants and grow monsters on my varieties that are supposed to grow monsters. Gene Pool trumps. Same for taste IMO....Genes trump all.

Organicdan: Thank you for the educational link on how to train and prune tomatoes.

It helps to maximize the size of the tomato. I have one with a 16-inche circumference. I did not weight so I don't know how much and I gave it away so I don't know what it tastes like. All I've heard is that it was good.

Contrary to claims made by many, the research on the issue is rather extensive, and quite conclusively shows that pruning did not increase overall yields. Its effect on fruit size is debatable. These studies all seem to suffer from a number of methodological issues. First and foremost, most every study compared tomato plants staked and pruned to plants allowed to grow on the ground. This introduces too many dependent variables, and fails to examine the most important distinction: the difference between staked and pruned vs. staked and not pruned (which, after all, is what the question really is. As such, these studies most likely indicate issues with allowing the plant to sprawl directly on the ground more so than issues related to pruning.

As to fruit size, these experiments are complicated by the fact that they all seem to examine fruit as a percentage of overall yield rather than presenting absolute numbers, so it is difficult to determine from the results if the claims about larger fruit size are based on total harvest, or individual fruit. From the data, it most certainly could be that both methods produced the same absolute number of larger than average fruit, but that the plants that are not pruned, having a significantly larger yield, had a smaller percentage of larger fruit relative to the more abundant total harvest. Regardless, since individual fruit size is mostly a commercial concern, it is largely irrelevant for the home gardener.

Data on early yield is mixed. At most, it might lead to a slightly earlier first fruit set, due to stressing the plant.