Member discussion regarding the methods, varieties and merits of growing tomatoes.
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June 23, 2013 | #1 |
Tomatovillian™
Join Date: Jan 2011
Location: Annapolis, Maryland
Posts: 222
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How easy is it to get a bee cross?
This may sound like a stupid question, but how easy is it have a bee cross between varieties? I have about 50 different tomatoes this year and about 10 more that are duplicates of my favorites. I was in the yard yesterday morning and I watched a single bee go flower to flower (variety to variety) on just about every plant I had. I was extremely happy that I was getting the pollenation but was wondering if this automatically means cross-pollenation? Thanks!
Mark |
June 23, 2013 | #2 | |
Moderator Emeritus
Join Date: Jan 2006
Location: Upstate NY, zone 4b/5a
Posts: 21,169
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Quote:
Above is an excellet FAQ from GW on how to prevent cross pollination which I think will help. Seeing bees, the most common ones are the halictid sweat bees that are so tiny you seldom see them, but honey and bubmbles can also do it, does not automatically mean that X pollination has occurred since it takes, usually, several bee visits to a blossom to have enough pollen to fertilize the ovules in the tomato ovary. And most blossoms are self pollenized in the bud stage as the bud develops, so that's another factor as well. Carolyn
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Carolyn |
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June 23, 2013 | #3 |
Tomatovillian™
Join Date: Jan 2011
Location: Annapolis, Maryland
Posts: 222
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Thanks Carolyn!
This looked like a bumble or carpenter bee but had orangish things on it's legs. It did come back to the same flowers on a couple of plants after visiting other varieties so I guess we will see what happens? I don't trade seeds so I am not too concerned about keeping them pure. I was just wondering after watching the little critter working hard. I am glad to see you back on the board and I hope your health keeps improving! I don't post much but I do lurk on the board and I always enjoy your informative posts and insight!! Take care!! Mark |
June 23, 2013 | #4 |
Tomatovillian™
Join Date: May 2013
Location: Cache Valley, N/E of The Great Salt Lake
Posts: 1,244
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The natural cross pollination rate of tomatoes varies widely depending on what cultivar it is, and what pollinators are present, and how closely different varieties are planted together, and other factors. It is generally considered to be in the range of 1% to 9%. I use a rate of 5% as my working estimate when contemplating how many plants I need to plant in order to have a good chance of finding a natural hybrid.
I culture tomato pollinating insects, and grow plants that attract pollinators near the tomato patch. Anything to help increase the natural cross pollination rate. |
June 24, 2013 | #5 |
Tomatovillian™
Join Date: Jun 2006
Location: West Virginia - Zone 6
Posts: 594
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Several years ago Jeff McCormack did a study and wrote a paper about isolation distances regarding tomatoes. As a by product he determined that cross pollination occurs about 2% to 5% of the time when tomatoes are planted closely together. I think that is a fairly good general approximation and matches what I've experienced in my garden.
There are several factors which can contribute to cross pollination. These inlcude, but are not limited to, flower formation (long styles/exerted stigmas are more susceptible to cross pollination) and the type of bee (sweat bees are more likely to be cross pollinators than bumble bees). Just because you saw a bee go to several flowers on several plants doesn't mean that cross pollination occured. Generally pollination has happened by the time the flower opens. Randy |
June 24, 2013 | #6 |
Tomatovillian™
Join Date: Feb 2008
Location: Mid-Ohio
Posts: 847
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June 24, 2013 | #7 | |
Moderator Emeritus
Join Date: Jan 2006
Location: Upstate NY, zone 4b/5a
Posts: 21,169
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Quote:
I've linked to that article here many times, but don't have the time to do so right now. it's an excellent article for those interested and you have to remember that at the time Jeff owned SESE so his suggested distances are very conservative since he was selling seeds. Too conservative for me. I used to putmyplants in 250 ft rows, 3-4 ft apart and 5 ft between rows and my X pollination was about 5 % which means on average that of seed saved from 100 varieties that on average about 5 will be crossed. of the many many hundreds I use to SSE list I can remember less than 10 that were cross pollinated. But depending on all the variables discussed in Jeff's article, crossing rates up to 35-50% are possible. Carolyn
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Carolyn |
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June 24, 2013 | #8 |
Tomatovillian™
Join Date: Feb 2013
Location: Czech republic
Posts: 2,534
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Czech firms, which shop seeds (Moravoseed, SevaSeed, SEMO), must keep isolation distances (it is control by ÚKZUZ):
tomatoes, peppers and eggplants- 100 m cucumbers, squashes and melons - 1000 m Mr Big |
June 25, 2013 | #9 |
Tomatovillian™
Join Date: Jan 2007
Location: PNW
Posts: 4,743
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I have not seen one bee yet this spring, but looking at the tomato
flowers, I can tell that they have been there (ends of anther cones are all chewed up).
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-- alias |
June 25, 2013 | #10 |
Tomatovillian™
Join Date: Feb 2013
Location: Czech republic
Posts: 2,534
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I use these bags welded from non woven textile.
Vladimír |
June 25, 2013 | #11 |
Tomatovillian™
Join Date: Feb 2012
Location: Maryland's Eastern Shore
Posts: 993
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Just swat at him a few times. That should do it
(Sorry.... It was just kind of hanging there...)
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George _____________________________ "The tree of liberty must be refreshed from time to time with the blood of patriots and tyrants. It is it’s natural manure." Thomas Jefferson, 1787 |
June 25, 2013 | #12 |
Moderator Emeritus
Join Date: Jan 2006
Location: Upstate NY, zone 4b/5a
Posts: 21,169
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I mentioned the article written by Jeff
McCormack above but no one seems interested in fetching it. So between wicked T storms I did b'c I think it's a must read. http://www.southernexposure.com/isol...es-ezp-35.html Again, please remember that Jeff owned SESE so was commercial thus his isolation distances are very conservative. And I gave some data above on what my crossing rate was and how far apart I used to grow my tomatoes. Hope the above link helps, Carolyn
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Carolyn |
June 25, 2013 | #13 | |
Tomatovillian™
Join Date: May 2013
Location: New Mexico
Posts: 2,052
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Quote:
I wonder if using the toothbrush pollinating method can increase cross pollination between plants. I have plants pruned to 2 stems vertically, and spaced about 2 ft apart, and I use the toothbrush to enhance pollination which appears to be working. However, sometimes with the toothbrush stimulation I see pollen spewing out of a flower at an amazing volume into the general garden. Charley |
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June 25, 2013 | #14 | |
Moderator Emeritus
Join Date: Jan 2006
Location: Upstate NY, zone 4b/5a
Posts: 21,169
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Quote:
Carolyn
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Carolyn |
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June 26, 2013 | #15 | |
Tomatovillian™
Join Date: Jan 2007
Location: PNW
Posts: 4,743
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Quote:
"exerted stigmas", like Joseph. This picture of a flower on Gillogly Pink from TOMATObase shows what an exerted stigma looks like: http://tatianastomatobase.com/w/imag...nk_Flower2.jpg Wind could pick up pollen vibrated out of a flower and carry it to other flowers on nearby plants of other varieties. There are plenty of exerted stigma types among heirlooms, and some author named Gopalakrishnan in a 2007 book said that hot weather increases the tendency for tomato flowers to have exterted stigmas. Most growers have few plants like that, though. This Beauty King flower does not look so much exerted stigma as simply bee-chewed, where a bee grabbed ahold of the end of the anther cone and then did his vibrating thing to shake out the pollen: http://tatianastomatobase.com/w/imag...ng_Flower_.JPG These Break O' Day flowers are the kind that I see the most: http://tatianastomatobase.com/w/imag...ay_Flower2.jpg They are not likely to cross-pollenate, unless a bee with a belly covered with pollen from something else opens up the end of the anther cone before the flower has self-pollenated and gets pollen from another cultivar all over the pistil. Figure that any flowers that bees have opened up are probably already pollenated, so pollen wind drift from your vibrating device will not affect those. Once a flower has some color besides green, there is a good chance that it already self-pollenated.
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-- alias Last edited by dice; June 26, 2013 at 11:55 AM. Reason: sp |
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