If you type in cross-pollination in the search bar up top, there should be plenty of threads that tell you what you want to know. I remember reading a thread that said tomatoes only have a 5% chance of c/p, don't recall where it was though. How close are your tomato plants, and what kinds are you growing?

Abby

Here is a link that might be useful: tomatoes

I keep lots of data on the many seedlings I start, and using the incidence of regular leaf showing up in my potato leaf varieties, my conclusion is that I see about 0 to 5 % crossing, with plants about 3 feet apart and no bagging. I do tend to save seed from the first set fruit, prior to the bees getting really busy, which helps.

Thanks, NCtomatoman.

I don't mean to be lazy, but it is hard to find info by googling on this topic. I have read a few PhD botanists' essays on how to raise tomatoes, but no one seems to give an answer to the question of how common cross pollination is. All they say is that "to avoid cross pollination, a controlled environment is needed." I already knew that, but I also know people who raise consistent seed year after year while having other varieties close by. Hence the reason I asked my question.

NCtomatoman, you say you estimate 0-5% in your own garden, but my question is how can you be sure that cross pollination does not occur more often? I know you said you check the PL varieties vs. RL varieties, but isn't it still possible for a "Brandywine" PL to be hybridized with a RL variety and still exhibit PL qualities even after a cross? It is possible, for example, for a hybrid variety to have an ancestor that was PL, even though the hybrid shows RL. Or am I wrong? I am a complete newbie, so I am just speculating here. I am sure you probably know the answer for sure.

Thanks again!

"I know you said you check the PL varieties vs. RL varieties, but isn't it still possible for a "Brandywine" PL to be hybridized with a RL variety and still exhibit PL qualities even after a cross?"

Potato leaf is a recessive gene, it only shows up if both parents are PL, so if a PL got crossed by a RL, it would show up (when the seeds are grown) as RL. (short of some somatic mutation.)

I should note that my example above is referring to the immediate cross and hence the seeds would be F1, plus we are talking about homozygous, stable open-pollinated varieties.

Things change when you cross hybrids, and you may get a PL later down the F generations if the genes line up (cc) and PL was present in the genetic background somewhere in the past. I have a SunPlum F5 that is a Sungold F2 x Juliet F2 cross and while both are regular leaf, a PL just showed up in some of the F5 plants.

Thanks Korney.

So I assume that if I save the seed from my Brandywine PL plants, and they develop into PL plants next season, then I can deduce that they have stayed pure?

Regards.

Correct... unless it got crossed with another PL variety! But if it's your only PL, then they should be true.

Thanks a ton, korney. It has been a while since I studied Mendelian genetics in college. ;)

Have you, or anyone else here, ever intentionally created your own strain? If so, how good is the fruit? How about hybrids? Anyone have your own hybrid strain that you breed perenially?

This kind of thing is one of the most interesting aspects of gradening, even though this is my first season trying to garden. I have a lot to learn. Thanks again!

Take care.

cross pollination, it is a big concern in tomato seed saving.
They do cross pollinate, no doubt about that so if you want absolute certainty you should isolate them. Potatoleaf and white fruit varieties are considered more prone to cross pollination.
Cross pollination (manual or natural hybirds) can give you unwanted characteristcs but the chances are equally high that you get an even better variety. Nature depends on the natural phenomena of cross pollination to become better adjusted to living in certain conditions. We people like to collect certain varieties and want tomatoes with certain varieties (commercially : though tomato, ripening off homogenic, little skin defects,... amateurs : strange shapes, wellknown varieties, colour, taste,...) so to get the results you want after a seasons hard work it would be nice to have predictable seed.
Tomatoes self pollinate so by isolation you can continue the same bloodline, keepting the variety as is...