PCPoke,
I will give you my opinion which along with a couple of dollars will still buy you a cup of coffee at a few places. Yes it could possibly have some influence on the lack of fruit set. Not knowing what your temps have been and where you are located for sure I would imagine a part of the lack of set is due to swinging temps. When temps are over 90 or those lower than mid 40's at night I see poor fruit set usually. My fruit set has been poor so far but I've battled extremely low temps also and then a few days over 90. I wouldn't fertilize unless the plants show signs of needing something which I doubt they will. And imagine you will start seeing some fruit set soon. My own personal practice when I have the time is areas where I've either grown nitrogen fixing crops or added chicken manure is where I will plant my sweet corn. Then the next year plant tomatoes, peppers, ect. I've also planted okra is those areas with good results. Jay

PCPoke,

Welcome to the forum. I'm glad you decided to stop lurking and start posting so that we know you are "there".

Do you know what your temperatures have been in terms of highs/lows during the times the blossoms are shriveling and dropping?

Since you're in zone 6, it is most likely your nights have been a touch too cool and, if that is the case, as soon as the nights are consistently staying warmer, the blossom drop should cease. Blossoms also drop when temperatures are excessively high, so if you're in one of the western OK locations that has had highs in the upper 90s or low 100s already, that could be the problem.

Another possibility is that your plants are not getting enough wind movement. For example, if your plants are in a typical suburban back yard with a house, backyard shed and wood privacy fence and all these combine to fairly effectively block wind flow at the tomato plants' level, your tomato flowers might not be moving enough to shake the pollen loose inside the flowers. This also can occur during periods of high humidity which end to make the pollen 'sticky'. If you think that might be the problem, you can either thump each flower a couple of times daily (preferably early in the morning) or, if the plants are caged or staked, just grab hold of the stake or cage and shake it gently for a few seconds so the whole plant moves a little bit.

Excess nitrogen is unlikely to be playing a role here unless you're deliberately adding nitrogen to the bed, but I don't know enough about how you grew your beans and peas to give you a definitive answer. First of all, the roots of legumes do have the ability to fix nitrogen from the air with the roots. However, in order for the soil in the bed to benefit from that, you have to rototill all the plant debris into the beds after the plants are through producing. Then, as the plants decompose, they release nitrogen into the soil. If you pull and discard your plants after they're through growing, then they are not adding nitrogen to that bed. Even if you left last year's plants in the bed to decompose, once that has occured, the nitrogen doesn't just sit there and 'wait' months or years for plants to come use it. It is constantly being used up, washed/leached out, etc. so I find it unlikely your beds are too high in nitrogen based solely on beans and peas being grown there in the past. Also, while all legumes have the ability to fix nitrogen, not all of them do it at the same rate. The snap beans we grow in our gardens to eat as "green beans" (whether they are yellow, green, purple, pink or bi--colored/tri-colored) are among the least efficient of the legumes when it comes to fixing nitrogen and their effect in home vegetable gardens in terms of supplying nitrogen is misunderstood. I just don't think the beans alone would make your soil too nitrogen-rich.

Finally, in the same way that "a watched pot never boils", it seems like a "watched tomato plant never sets fruit". Try ignoring the tomato plants for a week or so and they'll set fruit just to get your attention. My plants always seem to set fruit the best when I'm so busy with other garden chores that I'm not paying any attention to them at all. Then, when life slows down and I catch up on all my chores and take the time to look at the plants, I am amazed at how many tomato blossoms and fruit just suddenly "came out of nowhere".

Dawn

Thanks for the replies. Sounds like the thing I need then is patience.

Another question since I have your attention...

Should I be pinching off blossoms to keep only a limited number on the plant at any given time to not waste energy or maximize the chance of fruit set? Or again, just let its do its thing and be patient?

PCPoke,
Personally I leave any blooms that come after I set them out and also any fruit set. There are many opinions on this. I used to pinch all blooms off before and for the first 10-14 days after transplant. Due to the weather extremes I've experienced the last 3-4 years I now leave them. Three years ago I didn't get those on a few plants and they were the only early tomatoes I had all summer. So the last 2 years I did some both ways and compared. Those plants where I left blooms and fruit in the end produced as much if not more and for a longer period. The plants might be a bit slower to reach full size but by Sept you couldn't tell them apart. Again a personal decision and one where I've changed my mind like so many things I do in gardening. I know others believe you should pinch them off. Again the best way it too try both and see what works best in your garden. That is what I finally did. Jay

No, no, no, no, and no!

You need to understand how tomato plants operate in our climate. They grow vigorously in our climate in May and June, and sometimes in April, if April is consistently warm enough. Once the intense summer heat arrives their growth slows down.

Air temperatures can prevent fruitset, so you need every possible blossom on the plants in May and June to ensure adequate fruitset while the temperatures are in the right range for pollination/fertilization to occur. If you remove blossoms during this 'prime time' for fruitset, you're going to have significantly fewer tomatoes.

Once the daytime highs are exceeding about 92-95 degrees, fruitset is impeded by the heat. Once the nighttime lows are exceeding about 72-75 degrees, fruit set is impeded. So, here in OK, we have a relatively narrow time frame in which nights and days both remain cool enough for tomato fruitset to occur. It is further complicated by the fact that temperatures which are too low (below about 55 degrees) also impede fruitset. We sometimes have a fairly narrow window of opportunity for blossoms to set fruit because sometimes the nighttime temperatures go from 'too low' to 'too high' in a ridiculously short period of time.

Humidity also plays a role in pollination/fertilization. I will see fruitset on my plants during drought even when temperatures are exceptionally high if the humidity is remaining exceptionally low.

This will make you laugh but it illustrates why you shouldn't remove blossoms (or too much foliage): When we lived in Texas, an unfriendly next-door neighbor decided to plant tomato plants in her backyard in almost full shade. Then, as the poor plants struggled to grow at all in the shade, she methodically picked off every blossom and most of the leaves. Finally, in mid- to late-summer, her spouse asked me why her plants were not producing fruit like ours were. (She wouldn't ask because she didn't speak to us or to any of the other neighbors as near as I could tell.)

Struggling to control my urge to smile, I solemnly told him that every time she was pinching off a flower, she was 'killing' a potential tomato. No blossoms. No fruit. I also told him that she was removing too much foliage and that I neither pruned off foliage or pinched off blossoms. I explained that the leaves are important because they conduct photosynthesis which the plants need in order to grow and produce, and that the blossoms are the fruit! There was a long silence and then he concluded that he guessed he'd just keep his mouth shut and not say anything to her at all for the sake of keeping peace in the family. I nodded my head and agreed with him that keeping his mouth shut likely was a good idea since she was not the kind of person to take advice kindly.

I did always wonder if she ever figured out that she had no fruit because she left no blossoms on the plants.

There are valid reasons to pinch off blossoms in certain, highly specialized instances. For example, if you're a competitive tomato grower and are trying to raise gigantic tomatoes to enter in 'biggest tomato' contests, then you remove most of the blooms from a plant so that the few you leave on the plant will have the potential to produce the largest tomato possible. Another example would be in the autumn as your season is winding down. There's a point at which any flowers that form and set fruit will not have time to mature those fruit before frost arrives. So, some people begin pinching blossoms at that point so all the plants' energy goes into ripening the tomatoes already on the plant. Also, if stress causes a tomato plant to set blooms while the plant itself is just a few inches tall, it usually is better to pinch those off because the plants aren't large enough to support the fruit.

Pinching off blossoms gives you fewer but larger tomatoes and that's why some people do it. I'd rather have a lot of average-sized tomatoes than a few huge ones, though.

The only thing I remove from my plants are ripe tomatoes and the occasional horn worm. I don't even prune suckers unless I am going to use them to start new plants. That's what works for me.