Cross Pollination Question

[Jeepdog]

This is my second year growing heirloom tomatos. My question is, should I be concerned with cross pollination between varities? I am growing about 8 differnet varities within my garden. My beds are 4 X 8 and I have 8 plants per bed. 3 beds right now are filled and I expect to fill another two beds and some pots with transplants within the next week or two. If I save seed, should I be concerned with cross pollination? I live in a rural area and there are no other gardens within probably a good 1/4 mile of my location, that I am aware of. Just wondering. I saved seed last year for the first time without ever thinking about this. Then someone asked me this question the other day and I was at a loss for an answer. Just wondering now that the question was posed to me. Would appricate your thoughts on this.

Thanks

[cornbreadlouie]

I think a lot of it depends on the plant. Some varieties the stigma was visible, while a lot of my other tomatoes it was completely covered by anther cone. My "black krim" I noticed the anther cone stuck out a bit, and surprise, surprise it grew out as some sort of red tomato. Delicious so I'm not going to complain but I hope I dont have to grow out 40 seeds to get the plant I'm lookin for next year.

Might as well keep saving them and growing them out but you might want to save seeds from at least 2 or 3 tomatoes/plants to insure at least one plant will grow out true to type.

[sirtanon]

You might also consider bagging at least one cluster of blossoms per plant and only save from those.

[Ruth_10]

The number people guesstimate for cross-pollination of unbagged tomato flowers is about 5%. Close planting (8 plants in an 8x4 bed might be considered 'close') will up the possibility of cross pollination occuring.

[travis]

How exactly does planting 8 plants vs 6 plants in a 4' x 8' bed up the chances of cross pollination between plants? Please be specific.

[Ruth_10]

Originally Posted by travis

How exactly does planting 8 plants vs 6 plants in a 4' x 8' bed up the chances of cross pollination between plants? Please be specific.

No 'exactly' or 'specific' here--notice the waffle words I used in my above post--the 5% number is an estimate I've seen used here. There may be studies that someone is aware of; if so, I hope they speak up.

You ask how exactly does planting 8 plants vs 6 plants in a bed up the chances. I would answer there is probably not much difference. If your plants are touching or the vines are intertwined, then I would regard that as "close." If a bee or some other insect is burrowing into a blossom and picking up pollen, then going to the next blossom it comes upon, that blossom might be from another plant. That of course could happen if your plants are ten feet away from each other, but the chances are higher if the plants are touching or intertwined.

I apologize for not being specific. If the 5% number is even close, it's really more like 5% plus or minus 5%.

[carolyn137]

Crossing rates for tomatoes can vary widely from 0 up to sometimes almost 50% b'c there are so many variables that are involved.

I've posted here that I know my crossing rate is around 5%, which means statistically seed from fruits from 5 plants out of a 100 might be expected to cross.

It depends ifpollinators in your area are most prevalent early or late in the season and so much more

There are lots of variables, as I said above, and I'm going to link to an article written by Jeff McCormack, the original owner of SESE, who describes them, as related to NCP ( natura cross pollination). I think Jeff is a bit conservative on his isolation distances but at the time he was producing seed commercially for SESE.

And when you think about the small family owned seed companies that many deal with do you really think they bag blossoms? I do know that Glenn at Sandhill and Adam at Gleckler sell no seed over two years old, and especially for Glenn who lists about 400 tomato varieties you can just imagine how many plants he has to put out each year. And yet few of the varieties sent out by either Glenn or Adam, or whomever who don't bag blossoms, are crossed.

So here's the link from Jeff:

http://www.southernexposure.com/isol...es-ezp-35.html

And here's a link to a FAQ from GW on how to prevent X pollination with statistics, pictures and so much more and I think it's one of the best articles around about this subject and a must read.

http://faq.gardenweb.com/faq/lists/t...852004159.html

And yes, you'll see some user names at the bottom of the article that you might recognize, but in reality it was a group project.

[travis]

I've watched honey bees buzz from one blossom to the next gathering nectar from flowers, yes. But the kinds of bees that gather pollen seem to jump randomly and much greater distances when moving from one tomato blossom to the next, sometimes several yards rather than a few inches of feet.

[carolyn137]

Originally Posted by travis

I've watched honey bees buzz from one blossom to the next gathering nectar from flowers, yes. But the kinds of bees that gather pollen seem to jump randomly and much greater distances when moving from one tomato blossom to the next, sometimes several yards rather than a few inches of feet.

Travis, last I knew insect pollinators go to tomato blossoms not for nectar b'c the blossoms don't have any, rather, they go for the pollen as a protein source.

I don't know where I read it, but I did read somewhere that bees could fly up to a mile, one way, ahem, but I suppose that would maybe refer to the kind of insect pollinator being mentioned.

In the link I gave to Jeff MCCormack's article he suggests that the most common type of bee that works tomato blossoms are tiny sweat bees, and I've read that elsewhere as well. That's not to say that honeybees and big ole bumble bees haven't been involved as well.

About the blossoms not having nectar, I thought I'd better spend a few minutes trying to find that info, and so I did:

(Tomato flowers do not give the bees nectar, only pollen, but this pollen is gathered by the bees for the nutrition of their young. As they do so, they make a trade with the tomato plants by aiding the fertilization of the seeds that will make next year’s crop.)

........the above from the link below in the second article:

http://pollinator.com/blog/

Actually I was pleasantly pleased with what I learned from this blog but didn't take time to read all the articles this AM but I'll be going back to read more.

[travis]

Carolyn, I reread my post, and yes, when I mentioned honeybees gathering nectar, I should've clarified that the flowers I was speaking of were flowers and fruit other than tomatoes, like apples and honeysuckle, etc. Yes, the types of bees visiting tomato flowers are gathering pollen for protein for their young. I've only seen one honeybee ever on a tomato flower and I think he was either cold or confused.

[carolyn137]

Originally Posted by travis

Carolyn, I reread my post, and yes, when I mentioned honeybees gathering nectar, I should've clarified that the flowers I was speaking of were flowers and fruit other than tomatoes, like apples and honeysuckle, etc. Yes, the types of bees visiting tomato flowers are gathering pollen for protein for their young. I've only seen one honeybee ever on a tomato flower and I think he was either cold or confused.

That one honeybee was probably a mutant, didn't get the right genetic info from the Queen Bee. How sad.

But Queen Bees rule, why else would they have all those servants; I should be as lucky although not a Queen Bee last I knew b'c they don't know how to type and I do.

[dice]

I have watched a bumblebee travel down a row. He was 4' off the ground,
and he would travel around a plant at that height, buzz any open flowers,
then move to the next plant and do the same thing. He did not travel up
or down the plant, even if there were flower clusters with open flowers
above or below the ones at the height that he apparently preferred at
that time of year.

Even so, I get 5% or less cross-pollenation. (What is annoying is when I
send out 500 seeds of something without a mention of crossed plants,
then grow one myself from those same seeds to restock my seed supply
of that cultivar, and I get some bee experiment instead of the original.
Oh well, "next year".)

[Dutch]

The tomatoes that I grow for seed saving, I grows on the ground (actual on mulch) . My thinking has been that this will lower the chance of cross pollination. Does this have any merit?
Dutch

[afrance30]

Originally Posted by Dutch

The tomatoes that I grow for seed saving, I grows on the ground (actual on mulch) . My thinking has been that this will lower the chance of cross pollination. Does this have any merit?
Dutch

Do you mean you let the plants sprawl instead of caging or staking?

Ants might be an issue if you do that? Bees are rare on my property (although I think I am seeing more each year, probably because of the garden) but there are always plenty of ants crawling in and out of flowers. Without them I don't think any of my cukes (besides Diva) would set fruit. Same for melons and so on. In my garden ants rule, and I have learned to leave them the heck alone. I used to live in Georgia and ants there were a major problem (fire ants), but these little black ants I have here and extremely helpful. However, if they come in my house they must die!

[Dutch]

Originally Posted by afrance30

Do you mean you let the plants sprawl instead of caging or staking?

Yep. Just letting them sprawl. Thanks for the reply.
I am not necessarily looking for hard facts, but I am interested in other peoples opinions.
My own experience has been that I have had some natural crosses with tomatoes plants that were supported (staked), but not when they were sprawled on the ground.
Dutch