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Do I need to segregate my varieties?

Posted by bfreeman_sunset20 Ca 9b vta co (My Page) on
Thu, Feb 8, 07 at 12:39

I am thinking of saving my beans, peas, and maybe pepper seeds this year. Possibly heirloom toms too. Carrots and radishes and cole crops? I might go nuts on this!

The thing I fear is cross pollination changing the variety! Will green and wax bush beans next to each other cross pollinate and cause a mixed seedling? How bout purple and yellow carrots? Snap and shelling peas?

I remember hearing peppers dont cross pollinate well and are good for saving, what other veggies are likely to stay the same variety amongst others? What do you do for this dilema?


Follow-Up Postings:

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RE: Do I need to segregate my varieties?

  • Posted by remy 6WNY (My Page) on
    Fri, Feb 9, 07 at 18:31

Hi,
You do need to segregate certain veggies or you will get crossing. Some things cross more readily than others. Oh, and they must not be hybrid because saved seed won't produce the same plants.
Peppers cross pretty easily with their open flowers. Tomatoes don't cross pollinate as easy. Beans will cross. Of course if you stagger plantings so they bloom at different times crossing will be less of an issue.
If you are serious about continuing to save seeds from veggie crops, I suggest buying 'Seed to Seed' by Susan Ashworth. It covers all types of possible crops.
Remy

Here is a link that might be useful: Seed to Seed at Amazon


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RE: Do I need to segregate my varieties?

  • Posted by weed OR 6/7 (My Page) on
    Fri, Feb 9, 07 at 22:30

Hi,

First I will respectfully correct my colleague above. Beans and peas do not cross to an appreciable degree - possibly 1-5% according to some, less according to others. The floral structure of these legumes somewhat precludes outcrossing. The only exception to this I can think of at the moment are fava beans which are bee pollinated.

Carrots readily cross so need to be separated by distance or hand pollinated and the flowers bagged. Radishes readily cross with other radishes - of all types that I can think of at the moment. Cole crops are obligate outcrossers so they must have segregation.

Regarding what to do. Options are cages to exclude bees or hand-pollinating and bagging; physical distance separation, but most home gardeners don't have the distances required. Another option is to work with other seed savers and spread the wealth around, so to speak - one grows one carrot, another grows a different carrot and you share seed.

"I might go nuts on this!" Well, we hope you don't go nuts :) If you do a little research on each of your crop families it should become clear to you.


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RE: Do I need to segregate my varieties?

I concur with Remy's book recommendation (for "Seed to Seed"); if you wish to save seeds successfully, it is enormously helpful. If you will be saving seeds of anything irreplaceable, I would make it "required reading". ;-)

It might also be a good idea to check some of the other forums (both FAQ's & threads) since this topic is frequently discussed. The Bean Forum & Tomato Forum, for example, contain extensive discussions on the issues of cross-pollination, and saving pure seed. Expect to see some disagreement... in the end, it will come down to what works for you.

That being said... Befreeman, you have asked a complex question, which I will try to answer as briefly as possible.

Most vegetables are either "out-crossing" (require wind or insects to set seed) or "in-crossing" (will self-pollinate without help). Each group requires different treatment.

Out-crossing species include:
- Alliums (onions, chives, & leeks)
- Beets (wind pollinated)
- Brassicas (a.k.a. cole crops) such as cabbage, mustard, broccoli, turnip, raddish, etc.
- Cucurbits (gourd family) including squash, melon, cucumber, gourd, watermelon, etc.
- Grasses (corn) (wind pollinated)
- Umbelliferae (carrots, parsnips, celery, dill)

Since these species require wind or insects to make seed & are usually self-infertile, they can not be caged (unless they will be hand pollinated) so you can normally only save seed from one variety each year. Carrots, parsnips, radishes, & mustard can be especially difficult, since their wild relatives are common, and they will cross readily. Corn, since it can be contaminated by local fields, takes especially intensive methods to produce pure seed & is not recommended for the casual seed saver. Out-crossers may also be contaminated from vegetables grown by your neighbors (especially the cucurbits).

If you still wish to grow more than one of a particular out-crossing species, Weed gave some viable options. If you have time in the morning to do it, hand-pollination works well for cucurbits; friends & relatives can help with the others. You can also use an "alternate-day caging" method, where you place a cage over one variety (#2) after dark, allow the bees to pollinate #1 the following day, then move the cage to #1 after dark & allow the bees to pollinate #2 the next day. Continue back & forth for at least two weeks, or until flowering has ceased.

Just do some additional research; most out-crossers require a minimum population for seed saving purposes.

In-crossing species include:
- Legumes (bean, pea, lima, runner bean, soybean, cowpea, peanut, etc.)
- Nightshades (tomato, pepper, eggplant, potato, tomatillo)

These species are usually self-fertile, but a few (such as eggplant, runner beans & limas) seem to require insects to some extent.

However, many in-crossers will cross-pollinate heavily if grown in close proximity; limas, runner beans, eggplant, and peppers fall into this category. They should be treated the same as out-crossers (grow only one), or in the case of peppers, caged to exclude insects.

As for beans & tomatoes... there is considerable disagreement. Some people have no problems with different varieties grown side-by-side, while others have extensive crossing. Personally, I dont put much stock in quoted percentages of crossing, since this varies widely, and there are too many factors involved. I can tell you that I grow many varieties of both every year, obtained from Seed Savers Exchange members & seed swaps; and in my experience, crossing - sometimes severe - has been quite frequent.

Three bean varieties last year (out of fifteen) were so badly contaminated that their seed could not be saved; as it was for one bean and three tomatoes the year before. There are also the cases of minor crossing, where I rogue out & destroy one or two crosses, and am then able to save seed. This seems to indicate that the isolation methods used by many gardeners are inadequate. I tend to err on the side of caution; better to be too careful than too lax, especially if I intend to share seed with others.

My recommendation for beans & tomatoes is to use the barrier crop method (with tall flowering plants separating different varieties of the same species) and to place as much distance between them as possible. This is not as difficult as it sounds, even for those with small lots. I plant some of my rarest varieties in large pots lining my front sidewalk; the neighbors get a real kick out of my "flowers".

For the tomatoes that are most likely to cross (potato-leaf, currant, and some older varieties with a protruding stigma) or if many varieties will be grown directly adjacent to one another, blossom bagging with pieces of floating row cover can be effective. For all but the smallest varieties, you don't need to do many flowers to get a lot of seed.


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RE: Do I need to segregate my varieties?

What are the cages made of? Is there something you can make at home if you just have a few you need to isolate like this?


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RE: Do I need to segregate my varieties?

Isolation cages can be frames of PVC, metal, or wood, with a cover of spun polyester (Remay, Agribon, etc.), translucent screen, or any other material that allows light & air while excluding insects. Or for shorter plants, it can be as simple as floating row cover stretched over wire or PVC hoops stuck into the ground.

My own cages (which I use mostly for peppers) use 1/2" PVC for the frame; the legs fit over 24" stakes of 3/8" rebar driven into the ground. They are covered with Agribon fabric, held down at the edges with weights, making it easy to lift a side for weeding or harvest.

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The Seed Savers Exchange uses pre-constructed wooden screen panels, connected with hinges & clasps for easy assembly & removal. If you choose this method, be sure to cover the corners with fabric to exclude insects, perhaps held on with velcro.

There are many designs used by seed savers; you should make a cage that can be easily removed, preferably disassembled for easy storage over winter. I will be designing a few taller cages this year, for the tomato varieties that are most prone to crossing.

A few notes on cages from my personal experience... the spun polyester covers are excellent for peppers, because they tend to raise the heat & humidity inside the cage - and peppers thrive on both. Your caged peppers may be the best you have ever grown, especially if you garden in the higher latitudes. However, that same heat & humidity will promote disease in beans & tomatoes... so for those, blossom bagging is preferable to caging, or use a more breathable cover (light-translucent screen, for example) that provides better air flow.

If you live in an area with strong summer thunderstorms, use low-profile cages, and try to design a "safety valve" into your cages. Using weights or clothes pins to secure the cover means that it will be blown open - but not torn - in strong winds. After the storm has passed, simply re-attach the cover.


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RE: Oops, I forgot something

Re-reading my last post, I left something important out from the last paragraph above. If you are caging to produce pure seed & the cover is blown open, pinch off any open flowers before re-closing - you must assume them to be contaminated. Depending upon how long the cover was open, you might have to pinch off some of the smallest fruits as well.


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