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treated vs. untreated...what does this mean?

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  • treated vs. untreated...what does this mean?

    I've been looking at beans lately, and I've noticed that some catalogs emphasize that the seeds they sell are untreated. What are the seeds supposed to be treated with and how do you go about treating them? Is this essential or can you get away without it? Are beans the only kind of seeds that have this issue?

  • #2
    Of course you can get away without it, Mother Nature has never treated her seeds. But she cranks out seeds as a disposable food source to be eaten, for us the seeds are something we want to germinate.

    Some seeds are treated with a fungicidal powder that helps prevent them from rotting in cold damp soil. I think Captan is the most used form. I've seen beans, corn, peas and some melon seeds that have been treated with Captan, and I do think that there are likely many others too.

    I don't think I've ever seen treated 'dollar store' seeds. Treated seeds are going to be more costly.


    • #3
      Treated Seeds are typically treated with either Thiram or Captan as a preventative against damping off diseases. I think they were developed primarily so large scale growers could plant early with less worry about disease. Don't plant your seeds too early when the soil is still cold and you don't need them. I avoid them out of principle and never have any issues, I have no problem with fungicides when they are needed but treated seeds are totally unnecessary for home gardeners. The less captan in the world the better imo.


      • #4
        As a former garden center veggie/flower grower, yes treated seeds are more costly, are treated with either captan or thiram, as another poster said, and the chemicals are harmful if accidently ingested after handling them. I try never to use treated veggie seed, but sometimes did with certain varieties of flowers. Damping off can be prevented by not keeping your seed trays overly wet, just moist and not injuring the newly germinated seed stem. This can prove difficult if you're germinating on a heat mat, however. The ideal heat mat would be loosely enclosed in a small space with a small space beneath the seed tray to help prevent drying out and light air circulation. If damping off is a problem, you can place your perforated bottomed seed tray in another larger tray (like a cookie sheet) and bottom watering, being careful not to overwater and letting seed starting medium become soggy. If you use a seed tray dome (I use when germinating seeds that benefit from light exposure while keeping the moisture in), take it off after good growth is evident (especially important when trying to grow seeds like lobelia). Hope this info helps!


        • #5

          Don't forget to use bean/legume innoculant. Fixes nitrogen for a better growth.


          • #6
            I think they were developed primarily so large scale growers could plant early with less worry about disease.
            Probably true. I have seen small packets of treated seed, usually sweet corn, tomatoes, peppers, or vine crops. Since many gardeners are organic, companies that sell untreated seed usually emphasize that point. The same issues can be overcome without poisons, by the use of transplants. Obviously, this would not be practical for bush beans... but pole beans, especially pole limas, are very cost-effective as transplants.

            Don't forget to use bean/legume innoculant. Fixes nitrogen for a better growth.
            I use inoculants on all of my legumes (at considerable expense), but IMO, the jury's still out on their effectiveness. In 2007 I conducted an experiment on several legume species, with equal rows of treated vs. untreated. All of the crops were grown for dry seed, which was then measured & compared. Several problems interfered with the scientific validity of the experiment, such as rabbit damage, disease, and a few seed lots being accidentally mixed by a helper... but over all, the minor differences observed were well within normal deviations. This was true for common beans, runner beans, soybeans, garbanzos, and green gram.

            The only noticeable difference was for cowpeas. The treated plants had more pods, and these pods tended to have more peas than the untreated plants. Part II of this observation was unplanned... because of the experiment, I inadvertently withheld inoculant from my yardlongs, which I have always treated. The vines were much weaker, and the plants were slower to establish & yielded poorly. Because of these observations, I still strongly advocate the use of the proper inoculant for cowpeas & yardlongs.

            Since I had used all of the inoculants previously in the same ground (except for the garbanzo), it may be that they were already present in the untreated rows in sufficient numbers... so this only proved that annual application was ineffective. Also, the soil in that plot is very fertile, and nodulation of legumes is lower where fertility is high. On new ground, or on sandy or infertile soils, inoculants might be more effective.

            As for the cowpeas... perhaps that bacteria is less able to weather my severe winters, or perhaps the cowpeas are just heavier feeders. They have the largest nodules of any legume I have grown.


            • #7
              What's the shelf life of the innoculant? Can I just buy a big bag of it and use it for several years?


              • #8
                Every time I use untreated bean seeds, I have a germination problem. Undoubtedly the seeds are planted in a too-cold soil and are starting to rot before the soil warms to the temperature needed for germination.

                But my real problem is my short 90 day growing season. I live in a mountain valley of Northern Utah. If I do not get my seeds planted early enough, I will not get a harvest by fall. These conditions mandate that I start the seeds early enough to get a harvest, and this means I need to gamble with calendar date and soil temperature.

                This means I am forced to plant extremely early and quick-maturing beans, or use treated seed. I have gone to an early variety and untreated seed, and have just been accepting of the poor germination.

                Any suggestions for this dilemma of mine? Is Captan that bad?

                I am currently saving seed from my beans, so if I even used Captan, I'd have to buy it and treat my own seed, which I probably wouldn't do. But even saving seed is a less than ideal option because the frosts come so early in most years that the pods don't mature well.


                • #9
                  Kelly's Garden; Imo Captan is not a nice substance (carcinogenic), though the amount you will be exposed to or introduce into the environment on treated seed is fairly miniscule and not much to worry about, especially considering you have likely been eating it for years. An important thing I like to remember when it comes to any pesticide is that some worker has to work in a factory making the stuff (often in developing nations) and in this type of situation it could quite well have serious health affects for the worker. I choose not to support this whenever possible.

                  I doubt that you would be adding much if anything to your season by planting when the soil is not sufficiently warm. When large scale farmers plant early it is not to get a jump on the season but because they will not get their whole acreage planted in time unless they start early. Why not plant in flats first and then transplant? Flat soil will warm much quicker than your garden. You could also consider one of the many biofungicides like trichoderma (rootshield) bacilus subtilis (serenade, subtilex etc.) or gliocladium, these are available as separate products or mixed into seedling mix. They are much more powerful and safe than captan imo, although they are not curative they must be used preventatively.