The Big Clean

2019 will be a big year for Cultivariable.  We are revolutionizing the way that we grow.  There will be many long term benefits, but some short term pain.

When we started Cultivariable, there weren’t a lot of examples to follow.  There are few nurseries that are built around breeding new varieties and almost none working on the crops that we breed.  So, it has been a big learning experience and some of the most important lessons have illustrated that there are better ways to do this.

The five core crops that we work with, mashua, oca, potato, ulluco, and yacon, are all clonally propagated.  The problem with clonally propagated crops is that they accumulate diseases, particularly viruses.  There is no way to cure infected plants in the field.  Because of this, varieties tend to become more and more heavily infected over time, until they are “run out,” or “exhausted,” which simply means that they are so sick that they no longer yield well.  Many of the heirloom varieties that we grow have probably been accumulating viruses for decades.  This is further complicated by the fact that all five of these crops share at least some viruses.  The more varieties that we breed, the larger the collection gets and the larger the collection gets, the more difficult the problem of disease management becomes.

There are ways to clean these crops of viruses.  This involves a combination of laboratory techniques, including treatment with heat, treatment with chemicals, and culturing very small cuttings from the growing tips of the plants.  I have been practicing these techniques for the past five years, with some successes in restoring fertility to varieties that had been heavily infected.  I now have enough experience to know that cleaning up the entire collection is merely a matter of time and resources.  So, it is time to make the leap.  After we finish selling this winter, I will remove all varieties of these crops from the catalog and return them only after they have been confirmed to be free of all viruses.  A few are already tested clean, others will turn out to be clean and require only testing to confirm it.  Those will be returned to the catalog quickly.  Other varieties may take two years or more to clean up. 

The easiest and best way to make this change is all at once, so I have decided not to grow anything for sale in 2019.  We will offer seeds that are still in stock, but no roots and tubers until 2020.

Going forward, we will be offering tubers that are are only two years out of clean tissue cultures.  Each year, tissue culture plantlets will be grown out in screened containers to produce a foundation crop of seed tubers.  We will then grow those in the field and offer the resulting crop for sale.  This is a more conservative growing model than even certified seed potato programs use and should result in offerings that are almost entirely disease free.  I also anticipate being able to offer tissue cultured plantlets and microtubers that can be guaranteed 100% clean for those with really stringent requirements.

All of this will be a lot more work and you will notice some streamlining going on.  I will be dropping many of my smallest projects, at least temporarily, to focus on the core crops.  Some categories will disappear from the catalog, possibly forever in some cases.

It is hard to overstate the benefits that this change will bring.  It will result in a higher quality product for you.  Viruses affect plants in many ways and yield, fertility, and environmental tolerance all suffer.  A clean field will also protect our breeding work and possibly speed up the introduction of new varieties.  One thing I am particularly looking forward to is being able to introduce more potato varieties.  I have been reluctant to introduce very many because potato is the most difficult of these crops to keep free of viruses.  I will now be able to maintain and offer clean varieties with confidence.

Stick with us – it will be worth the wait!

2 thoughts on “The Big Clean

  1. mjjennings80 says:

    Wow, what a mind-blowing announcement! Sounds like a great plan. I have a hard time picturing what this cleaning process looks like. It would be cool to see some photos of the process and of the setup you are using to accomplish this feat. Will you be cleaning dahlia varieties too?

    I hope to some day be able to clean up my sweet potato varieties. Do you think that would require the same process you are using?


    • bill says:

      Thanks Mike. I will do some blogging over this next year to detail the process and the results. The fundamental technique is called meristem culture, so you can find some additional details that way. The exact process varies from species to species and also depends on what viruses are present, but it is pretty similar for all tuber forming crops. Sweet potatoes can definitely be cleaned up the same way. I will be cleaning up our dahlias and other clonally propagated crops as well, but those might take another year.

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