Isolation Distances
 

This might not be a technical crossing question, but seemed like the right place to post...

For personal seed-saving purposes and seed-sharing here and among friends, or for SSE for example; what are the recommended distances? I've read Carolyn's book and her recommendations; plants 3' apart and rows 5' apart, which sounds so reasonable and achievable for me. But I also read in William Woys Weaver's book that Potato Leaf varieties are more likely to cross and should be isolated up to 50'. What to do?

Could you share personal experience with Potato Leaf varieties.

Thanks!
Lisa

It's all about the bees. If you don't bag blossoms, then heavy bee activity in your yard makes the isolation distance thing moot (how fast can a bee get from one side of a 50 foot garden to the other!). And with tomatoes it is not about wind pollination - it is about insects.

So, I plant my tomatoes 3 feet apart in rows 4 feet apart, but save seed either early (before heavy bee activity) or late (more risky, but after bee activity subsides). My success rate has been excellent.

And - no, potato leaf varieties are no more apt to cross. It is just easier to notice, since it is a recessive trait. I grow lots of potato leaf varieties and my seed purity has been 95% or so. Any heirloom beefsteak variety has stigmas that extend beyond the anther cone, as well as the occasional very large marigold type blossom that is likely more attractive to pollinators.

So, to be on the absolute safe side, bag. Or, if you know your bees, don't.

The other point, and this is key, is that tomato flowers being "perfect" (both male and female parts), the vast majority pollinate upon opening - so even bee visitation would not cause problems if it is already a done deal.

Isolation Distance
 

Lisa,
I usually separate my PL varieties by 6 to 8 feet in all directions and get cross pollination rates of about 3%.

Is it the dry climate and low humidity and the corresponding low insect populations, or the fact that all my growing is entirely in containers where I can train my plants in a narrow tall profile, I don't know. All of these factors I'm sure work together to lower the crossing percentage.
I have very few bees and other insects here and the bees avoid the tomato flowers, only visiting them when there are no other flowers available.

Maybe it is the daily shaking I give each spudleaf with my electric toothbrush and stake hitting that causes a lot of self pollination before the insects can get to the blooms.

I'll find out this year if I see increased cross pollination as I'm planning to growout 80 different spudleafs with minimal spacing of 5 feet in all directions between plants. "The squeeze is on in spudleaf country!!"

Spud

Thank you, Craig. I will certainly pay closer attention to my bee population. We do have sweat bees, and [b]didn't I read that they are more likely to do the pollinating? [/b] I have noticed mediocre bee activity in the early morning among the squash blossoms here as compared to my Alabama garden years ago.

If I plant lots of flowers in a separate area of the garden, will the bee activity go there instead of the tomato patch?

SpudLeaf, good luck to you. It will be very interesting to hear your results after changing your planting method.

So, if I follow the 3' apart by 5' rows, I should be fairly confident with my seed sharing?

Thanks for your help!
Lisa

I found that it was easiest to just bag the blossoms for saved seed. Then I can plant as close as I want and not worry so much when I see bee activity.

The bags are not all that expensive online or from WalMart if you are only bagging a few blossoms. You do need fine-mesh tulle bags because some of the smallest pollinating bees can fit through the mesh in cheesecloth or nylon netting. You can also use a piece of row cover secured with a twistie.

I have flowers planted in several places around the yard and still see bees working the tomato blossoms, so I don't think planting flowers in a separate area will help.

For whatever reason, the Bumblebees in my Raleigh garden really work my tomato flowers in the intense heat of the summer time....when I walk through my garden, it seems to hum and buzz!

Yes, the bumblers are very active around tomatoes.
I walk through my garden some summer days screaming
at the bees. "Get away from those tomato plants! Can't you see the perfectly nice squash and cucumber flowers?! Go pollinate them!"

And I thought gardening was supposed to be theraputic....

Lee

Lisa, your memory is correct in that it's the tiny sweat bees that do most of the X pollinating accordiung to the excellent article written by Dr Jeff McCormack that is still at SESE even though he no longer owns that company. Actually the blurbs and stuff went along with the sale.

I also have not had a greater degree of X pollination re PL/s. And the distances you mentioned from my book give me a cross rate of about only 5%, which means 5/100 varieties saved might be crossed, and that I accept since when I was growing huge numbers of plants and varieties I could not and would not bag blossoms.

About bee activity. IN some areas like my own, it's greatest in the early part of the season so I save seeds only from later fruits, and the reverse is true in other areas.

Weather for a season is important too since there's less activity when it's raining a lot.

And I'll just mention something else here that really is an annoyance to me.

I can save seeds and use that stock for several years, and/or use it to satify SSE requests and all plants are what they should be.

And then all of a sudden I or someone else comes up with a plant that is wrong.

What that means is that probably only ONE fruit I used to process for seeds was X pollinated, and I use many fruits, and that one fruit could have only a few seeds in it that were crossed.

If self pollenization doesn't lead to complete fertilization of ALL the ovules in the tomato ovary, then any foreign pollen that lands on the stigma can do the job.

Not that it's really relevant, but here in Oz we have a bee called the Blue-banded Bee, just slightly smaller than the European Honey Bee,that just adores tomato blossoms. They land on them then buzz them to make the pollen fall out. They also love melon flowers and, at least where I am, we get great melon set. There is also a very small bee, probably similar to your sweat bee, which loves all the flowers that the European Honey Bee ignores, especially tomato and melon flowers.
It's great for fruit set but a nuisance for seed saving!