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need help on beans crossing info

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  • #16
    Limas will cross with other limas to some extent, if you grow more than one. Likewise, runner beans will cross with other runner beans. Both are very attractive to bees, and might even cross with limas & runner beans grown by neighbors nearby. However, limas & runner beans will not cross with each other.

    As a rule, common beans cross very little. However, Nature is good at breaking rules. I've received beans that were heavily crossed, one about 50%, and one (Jeminez) so badly crossed that I could not identify which plant - if any - was what the original was supposed to look like!

    Some varieties may be more prone to crossing. Jeminez may be one of those. I & others have experienced trouble with Goose, and another SSE member has reported trouble with one of his greasy beans.

    The number & species of pollinators, and the availability of other pollen & nectar sources may also be factors. Environment may play a role, if it inhibits self-pollination long enough for the flower to open, and to allow fertilization by foreign pollen.

    The point is that while crossing between common beans generally occurs at a very low rate, it CAN occur at a high rate under some conditions. Some effort at isolation (by time, distance, barriers, bagging, etc.) should be used if growing several beans, especially if preserving an irreplaceable heirloom. I try to grow different beans a minimum of 30 feet apart, with barrier crops of limas, runner beans, squash, cukes, okra, or annual flowers between them... the method has been highly successful.
    Last edited by WI_HO_C; 05-25-2012, 01:55 AM. Reason: clarity


    • #17
      "The number & species of pollinators, and the availability of other pollen & nectar sources may also be factors. Environment may play a role, if it inhibits self-pollination long enough for the flower to open, and to allow fertilization by foreign pollen."

      This is a very valid point and should be considered. Isolate your beans as far from each other as you can. If you have a small garden space just plant anyway and you will be fine, most of the time. Nature does indeed seem to find a way. The large bumble bees that live underground are concentrated on the north end of the farm where I grow my seed. Outcrossing is less on the south end. We followed some of these apids 1/4 of a mile and feel that is about their maximum foraging distance. Different years can make a difference. I plant a few rows of sunflowers to attract the bees and hopefully keep them out of the important increases.


      • #18
        The OP specifically asked if the types of beans listed would intercross. The answer first given is partially correct that most bush beans and pole beans are Phaseolus Vulgaris and are capable of crossing. What is missing from that explanation is that there are 5 subspecies in Phaseolus Vulgaris and there are partial crossing barriers between some of them. For example, viable crosses between most pole beans and most bush kidney beans are difficult to make.

        Here are a few general guidelines.

        Runner beans (Phaseolus Coccineus) readily cross with other runner beans. A separation distance of 150 feet with other crops planted in between especially of species like squash that are highly attractive to bees will very nearly eliminate crossing. Caveat that some areas have much higher pollinator populations so do your homework before planting more than one runner bean.

        Lima beans (Phaseolus Lunatus) have 2 common subspecies, the small seeded sieva types that produce best in the southern states, and the large seeded "potato" limas that produce best in the northern states. Sieva will readily cross with another sieva, but very rarely with potato limas. Potato limas will readily cross with other potato limas, but very rarely with sieva types.

        Common beans (Phaseolus Vulgaris) will readily cross with other common beans but with a range of viability depending on which subspecies is involved. Beans of the same subspecies are highly cross-fertile so if you grow Rattlesnake pole bean with Jeminez pole bean, there will be crosses typically at about 1% of the seed produced, but if you grow Rattlesnake with bush red kidney beans, crosses will be nearly nil and any resulting crossed plants exhibit problems with development.

        Tepary beans (Phaseolus Acutifolius) are a highly drought and disease tolerant subspecies that are rarely grown in most of the U.S. Crosses between tepary varieties occur at a low rate, but crosses between tepary beans and other members of the Phaseolus group are extremely rare to nearly impossible to make. I am growing Vax-1 which is Acutifolius X Vulgaris with hopes of crossing it with a nuna bean I am growing. I would love to have a temperate adapted heat tolerant nuna bean!

        English Peas (Pisum Sativum) are unrelated to the other beans listed and are not cross fertile except with other peas.

        Cowpeas and asparagus beans are subspecies of Vigna Unguiculata. While there are no major crossing barriers, these rarely cross because of the way the flower opens and relative rarity of pollinator visits.

        Fava beans (Vicia Faba) are another species that are interfertile with other favas but not with other species.

        You can read a little more about this on the bean wiki article.



        • #19
          You cannot usually tell from looking at the bean seed whether or not it is crossed.

          The above article was posted in a thread elsewhere on the net. It has a lot of info about beans and bean breeding.



          • #20
            Seed color is maternal, you will not see the results of the cross until the second generation.


            • #21
              Thank you. I was hoping that was not the case as I have a billion bumble bees. I'll be bagging and tagging.


              • #22
                Suzanne Ashworth sort of summed it up by saying to not plant two white-seeded varieties next to each other. If they did cross, you would never know it in later plantings. I don't plant the same color next to each other primarily to avoid mixing them when harvesting.


                • #23
                  Originally posted by greenfinger View Post
                  Can I plant ONE variety of each bean/pea, next to each other, from each of these groups without worrying about crossing?

                  Self-pollination is the rule among all legumes, but like people they don't always stick to the rules.... See below!

                  fava bean Vicia faba: mostly self-pollinating but crossing between cultivars can occur with much insect (bee) activity. Does not cross with any of the others.
                  runner bean Phaseolus coccineus: as fava bean
                  pole bean + bush bean both Phaseolus vulgaris: more strongly self-pollinating than the previous two. But if crossing does occur, it can just as easily be between a pole and a bush as between pole/pole or bush/bush
                  lima, bush or pole Phaseolus lunatus: up to 18% cross-pollination has been recorded between different cultivars, inculding between bush and pole. Does not cross with any of the others.
                  cowpeas Vigna unguiculata: up to 25% cross-pollination between cultivars can occur, especially in humid areas. Does not cross with any of the others.
                  english peas I think you mean the ordinary Pisum sativum? Almost entirely self-pollinating, like Phas. vulgaris
                  All of these can be fairly easily crossed by hand, but only within the species. Crosses between species won't work, even forced.


                  • #24
                    Originally posted by BeanMan View Post
                    Dry beans, Phaseolus vulgaris, are about 99% self pollinated. You can plant different cultivars side by side and get only about 1% outcrossing. It takes one of the larger Apidea (bumble bee) with a long proboscis to transfere pollen.
                    My info on Phaseolus vulgaris says 5% crosses, but my experience has been that crosses can be much more common. It seems to depend on the variety. Some never seem to cross while others seem to cross preferentially (which probably means that they are not crossing, but are, instead, unstable).


                    • #25
                      Though most of the time, different species won't cross with each other, there are some exceptions. For instance, I know that Phaseolus vulgaris (common beans) and Phaseolus acutifolius (tepary beans) can cross (Carol Deppe did it).

                      I plant common beans and runner beans next to each other and I haven't seen any crossing. I have a healthy population of all kinds of bee species here so I wouldn't risk planting multiple varieties of the same species right next to each other. But I could get away with a variety in the front yard and a variety in the back yard for sure. (100 feet apart with a house in between) Probably more than that.


                      • #26
                        Earthnut, I've seen the plants from the purported Acutifolius X Vulgaris cross. They appear to be pure Vulgaris. First generation crosses show distinctive traits that are easily recognized. The beans I have seen don't show any Acutifolius traits. I can't make any absolute statements, but at this time, I am leery of the supposed background genetics involved.


                        Nuna Frontina Negra

                        Nuna Mani Rojo

                        Oaxaca 5-1

                        Vax-4 (tepary cross)

                        Vax-3 (tepary cross)

                        Vax-1 (tepary cross)

                        Xan159 (tepary cross)

                        Purple Emerite (an ordinary pole bean for comparison)


                        • #27
                          I highly recommend Carol Deppe's excellent book, Breed Your Own Vegetable Varieties for detailed information on how to breed and what is required to save varieties.

                          As for growing pole beans, sturdy is not the word if you grow them on a fence or trellis. One good wind and all that foliage will take it down, which is why I use tepees.