Isolation distances

[George Sims]

Carolyn,

Picked up a copy of your book this week at Baker Creek, and am enjoying it immensely!! One question, however:

I've been saving seeds (from only a dozen or so vegetables, and only a couple of tomatoes) for the last two years.

You mention, "If you plan to save seed, you will need to separate tomato varieties. Different distances are recommended, depending on whom you consult. Commercial growers...need to obey the greatest isolation distances. For home use--when seeds will not be shared with others--a distance of 3 to 4 feet within a row, and 5 feet between rows, is usually adequate..."

I'm certainly no commercial grower, but plan to grow out a dozen or more tomato varieties next year. I want to be able to share seeds with others--through SSE and other outlets--though, and am concerned about cross-pollination, although you make it clear that the danger is rather slight. Space is not a problem. How far apart should my plots be? I plant to grow out about six plants of each variety.

[username5]

Carolyn will surely give you a better answer, but most (not all) tomatos varieties are difficult to cross polinate so it isn't much of a concern. For reasons that Carolyn will explain most tomato flowers are fully pollinated *before* they open and are available to insects.

The distance plants need to be apart is going to vary depending on whom is asked. It is the distance one requires to be reasonably sure insects don't carry pollen from one plant to another or that wind can't carry loose pollen.

In reality there is no such thing as a safe distance as (some) insects and pollen can travel hundreds of miles. Playing the odds though, the further the distance, the less likely the odds of cross pollination occurring.

If you bag plants to prevent pollen from being spread you can grow plants right next to each other.

[George Sims]

Don't plan to bag the plants, but will find it just as easy to create a dozen small, separate plots as one large one.

If I understand correctly, she is only getting about 5% cross-pollination when planting varieties immediately adjacent to one another. Is that an acceptable ratio? Can I drop it to 1% just by separating the varieties by a few dozen feet?

[username5]

Originally Posted by George Sims

If I understand correctly, she is only getting about 5% cross-pollination when planting varieties immediately adjacent to one another. Is that an acceptable ratio? Can I drop it to 1% just by separating the varieties by a few dozen feet?

I am going to let Carolyn address your questions, but I will address one question and that is whether or not a 5% or 1% cross ratio is acceptable.

I do not trade seeds. Why not? Because in my limited experience trading seeds there are too many crossed varieties or simply mislabeled seed packets.

I have a small garden area and even 1 plant that isn't true to type is a big problem. It means I don't get to enjoy that variety in that year.

For me *any* cross pollination is unacceptable.

The answer to your question then is 'What is acceptable to you?".

[George Sims]

Over the past year, I've gotten a lot of enjoyment from sharing seeds. I guess I'd hate to invest a year in planting a variety, then sending it on to someone else, only to learn that it was "tainted" (and I surely don't have enough knowledge or expertise to recognize that the variety was not true!).

I suppose that Carolyn could easily accept a 5% rate, since she is knowledgable, and would quickly spot the crosses. I'd prefer a much lesser rate, so as not to disappoint anyone who might get seed from me.

[carolyn137]

I suppose that Carolyn could easily accept a 5% rate, since she is knowledgable, and would quickly spot the crosses. I'd prefer a much lesser rate, so as not to disappoint anyone who might get seed from me.

Not true at all George, since most of the time the seed I save has been sent out re SSE requests or other requests before they are then saved for a year and regrown by me or someone else. And it would be the someone else since I'm not going to replant what I just saved seed from.

The problem can get complicated.

First, tomato pollen is not windborne, ever, so that's not a problem.

One problem is that while most of our garden tomatoes have stigmas that are below the pollen bearing anthers, which facilitates self pollenization, there are a few that still have exerted stigmas, no, there is no list, and thus can be easily pollinated by insects. And the insects that do most of the pollinating you can't see, for they are Halictid bees/aka Sweatbees, which are very tiny.

You have to hit a balance in this whole game.

Yes, my X pollination rate is about 5% which means that out of seed saved from 100 varieties, on average 5 will be X pollinated. Does that always happen? Nope, for it depends on the presence of insect pollinators, their frequency, the weather, etc., so each person has to build up info as to what they do get for a X pollination rate.

I grew about 500-1000 plants each summer for many years and the seed saved was destined for my SSE listings for I refuse to trade seeds unless someone offers me a new heirloom and then I ask what they might want.

Bagging blossoms with so many plants is just plain impossible.

So is using a greater isolation distance going to help you? Sure, but I can't predict how much without knowing what your base X pollination rate already is.

Are all the OP seeds sold pure? Absolutely not and for several years I kept a wrong varieties list at GW. Some are much better than others and it depends on whether they save their own seed, subcontract out or buy off the shelf.

If you were to do small plots at least 10-20 feet apart that certainly would help.

Are all seeds offered by SSE members pure? Of course not, but most folks can spot the off target plants and cull out the others.

Look at the blurb I wrote with my recent seed offer here at Tville where I wrote that I do not guarantee the purity of ANY variety. And that's the way it is.

So there's really no great way of escaping some X pollination, and you just have to decide how much is acceptable to you for your purposes.

And you're negver going to know which varieties are crossed until you grow them out and even then you might not.

I say that b'c in the few years I've distibuted over 300 varieties of my older seeds and some that I thought were pure were not. if the level of X pollination is low you may not see it until many many plants are planted out.

All it takes is one grain of foreign pollen to land on the stigma and fertilize one ovule in the tomato ovary to give X pollinated seed. And when saving seed from maybe 10 fruits and 9 are pure and the tenth has that one crossed seed, then the variety is crossed.

So rather than worrying about it all, I'd suggest that you increase the isolation distances from what I use since you have the room, and then perhaps determine what your own X pollination rate might be so you have a baseline to work with.

[George Sims]

Carolyn,

As always, you've been most gracious in taking the time to answer. I'm about to the "M" section in your book, and have already made a HUGE list of varieties I want to try. My wife, however, knows that I tend to plant more than I'll take care of.

As I have about 8 acres of bottomland, I expect I'll place smaller plots (to hold 5-6 plants) at least 20 feet apart, as you suggest.

I'd like to send you a sticker, if you'd be so kind as to autograph my book, if possible.

[feldon30]

And of course there are many varieties that Carolyn has discovered since the publication of that book such as Neves Azorean Red. And don't miss the last paragraph on page 43 where she indicates that some fantastic varieties were not available for photography such as Azoychka, Pruden's Purple, Jeff Davis, and Stump of the World.

[carolyn137]

I'd like to send you a sticker, if you'd be so kind as to autograph my book, if possible.

I'd be glad to George but you'll have to send me the book with a prepaid mailer to send it back in b'c my car is almost in the garage for the winter and then I'm housebound for the winter.

As my orthopedic surgeon says....Carolyn, take no risks, and if you fall don't tear anything more ( referring to all 4 quad muscles in the right leg that i severed in a fall on Dec. 12th, 2004), break something, and make it a clean break, no compound fractures.

Yes, it's almost two years in this walker now, with new left hip and the right one to go in next Spring and one quad muscle has not regained function which is why I'm still in the walker. Given the circumstances I'm just darn glad that leg is still attached to my body.

Em or PM me for my address if you don't have it and I guess I'll once again waive the $500 fee for autographing.

[Gimme3]

George...a Great question, that i never tire of hearing...heartfelt responses to. It's a tricky matter, sometimes, an it all depends on...the Goal ...)))

Dr. C...there's a Song...Stevie Ray Vaughn wrote an played....Sang. I can not...ever read your Eloquent posts, tryin to be as Accurate as a taught bow-string...without hearin Stevie's words....in my head. Some things in the Song...dont apply, and others, i'd jus hope...we got many more years to Hear...)))

i Applaud...the Accuracy...you so freely offer...Carolyn.

:wink:


edited because the wrong Smileys popped up...)))