Battle of the Genomes



There are more glamorous crops, but nothing in the vegetable garden is more rewarding than the lowly potato. Fresh-dug, organic, homegrown potatoes are dense, creamy, so flavorful as to need very little duding up. Conventionally grown potatoes, on the other hand, are so pumped up with artificial fertilizers and sprayed with such powerful chemicals–as Michael Pollan pointed out in a great piece in the New York Times Magazine eleven years ago–that they taste entirely too weird to eat.

Potatoes also deliver a huge amount of food for the land you devote to them. As a crop, they are so tough, they do equally well planted in April or July. You can steal little potatoes out of the ground early, before the whole clump is ready for harvest. And with some varieties fully grown in just two months, they are very useful for the seasonal orchestration that you have to have in a small garden.

So it's welcome news this week from New York Times that Cornell University is breeding new varieties particularly for my part of the world that may do better than the old standards.  They have a Yukon Gold replacement, Keuka Gold, that I will try next year, since I do Yukon Golds every year, even though they are not particularly productive in my garden. Why do I plant them? Because life is short and they are simply the most delicious variety of all, with their butter-colored flesh and thin skins. To find that flavor in a potato that produces more than a couple of spuds per plant…well, it's a potato obsessive's dream. My other favorites are All Blue, a flaky, dense potato that is excellent for baking, roasting, and mashing, and Sangre, a big productive storage variety.

Of course, all this potato celebration is wistful this year, since my second crop of potatoes, the big crop that I plant in mid-summer for storage, was entirely withered by late blight. Only a few of the seed potatoes I planted survived long enough to send up a leaf, and then the leaf instantly blackened as if someone had burned it.

Peculiarly enough, the Times potato story doesn't mention this regional tragedy–maybe because the piece ran in the "Dining" section, and no one wanted to put the readers off their food. However, this piece from The Cornell Chronicle shows how widespread late blight was in New York State even by July 10.

Why haven't we made much progress against this pest, a water mold called Phytophthora infestans, since the Irish potato famine of the 1840's?

This excellent article in New Scientist explains why it's so difficult to breed resistance into potatoes.  Their genetics are super-complicated, making trying out new crosses an unwieldy process.  (Unfortunately, you have to subscribe to New Scientist in order to access this link, something I highly recommend.  Very informative, very fun.) 

At the same time, the genome for the late blight pest, which was sequenced this year, is also a diabolically complicated piece of work.  A recent piece in Nature News, which includes an interview with Chad Nusbaum of the Broad Institute, one of the project's scientists, does a particularly good job of describing the lethal overkill that causes late blight:

When comparing P. infestans with similar
organisms in the same genus, stretches of the genome stood out as being
highly variable, unusually large and full of transposons — sequences
that make copies of themselves and jump around in the genome. The
researchers believe that the transposons, which make up about 74% of
this unusually unwieldy genome, code for the blight's 'weapons' against

"That is an insane number. For microbes, 25% is a lot," says Nusbaum.

So, there is not just an AK-47 in the house, but also a sharp ax, a bayonet, a
bow and arrow, and a rocket-launcher. And these weapons replicate their own parts and lend them to each other, too, allowing the mold to evolve new ways of killing
potatoes nearly as soon as a potato develops a new way of resisting it. Commercial growers control this problem with loads of fungicides, and according to New Scientist are constantly having to add more. Organic farmers use copper-based sprays.

I use nothing.  Ever since my first experience almost 20 years ago as a beginning gardener, sprinkling rotenone onto my roses to get rid of Japanese beetles–the beetles didn't mind, the roses did–I've never used any pesticide in my garden.  By now, I feel that anything that needs to be shaken out of a can or sprayed is antithetical to a healthy garden and a healthy mindset about gardening.

Next season, I'm sure to go naked and just move the potatoes to another section of the garden.  But if I lose most of them again, it's possible that the gardener, too, will evolve.


  1. Feel your pain about late blight. Here in Alabama, it’s much more likely to target our tomatoes. We just don’t grow a lot of potatoes here. I grow my tomatoes in containers with sterile potting mix and then mulched to reduce soil splashing since spores are found in soil. This has helped me avoid both early and late blight without resorting to fungicide applications.

  2. Love that you are promoting the potato! It’s such a great, nutrient dense food. But thanks to the villainization of carbs, the little guys aren’t so popular anymore.

    I look forward to including them in my organic garden this next spring and can’t wait to experience the delicious “peasant” of the food world. Maybe we can promote the uprising of the common vegetable. What’s next…Turnips?

  3. There are wild potatoes with a lot of resistance to late blight, but as you say, they are difficult to breed with domesticated potatoes. I know some researchers are trying to short cut the complications of the potato genome move the resistance genes over via genetic engineering — hoping that the public will be less freaked out by a potato engineered with a wild potato gene than they are by other GMO crops. I hope it works! Potatoes are too delicious to let some nasty Phytophthora get them down.

  4. I with you on loving those potatoes. I experienced my first digging-up-of-the-tubers event last summer, and it was divine (and I mean that more literally than figuratively). Because the plant is so modest, so undramatic, and because you can’t see the potatoes growing, it’s just heaven to pull out a plant and find 4, 5, maybe 6 beautiful perfect potatoes. Ahhh…
    And I’m with you completely on this too, for reasons I can’t explain but it’s a kind of stubbornness I think: “I feel that anything that needs to be shaken out of a can or sprayed is antithetical to a healthy garden and a healthy mindset about gardening.”

  5. Grew potatos for the first time and oh what fun and yum yum. Yukon gold and I think Kennebuc, an old standard. I got mine in on Saint Pt.’s day as I did my onions and peas. All did divinely. I had all my potatos (I have a very small garden) devoured by end of July. But I missed a tubor and I have one potato plant growing like mad. Didn’t know you could do a second season of pots. No potato blight in my garden, just tomato blight.
    And I agree,all the way with promoting ‘Peasant food’. Cabbage is another one that is so good grown at home and homemade krout cannot be beat.

  6. Michelle, I am so glad you mentioned turnips as well as parsnips! The landscape architect I work with mentioned parsnips as well just after I told him about this article. We are missing out on some amazing veggies.

    Onward with the common vegetable uprising!

  7. The late blight got my tomatoes mid season so it was only half of last years harvest. The early planted potatoes had already died back before the blight hit so I got a fine crop of them. A random potato planted in a vacant spot later in the season sprouted and then immediately keeled over with the blight. The monsoon is not your friend in the vegetable garden. If I see any potatoes sprout on their own next spring from missed spuds those will have to be dug and tossed because they could harbor the blight.

    My problem with turnips is if the cook turns up her nose at something we generally don’t get to eat it no matter how well I grow them. I have managed to change the cooks mind on beets and the green beans that left a lasting bad impression from childhood.

  8. All Blue definitely! Saved it for next year. Parsnips are awesome, watch out for skin irritation, I have seen some gnarly rashes from them. As far as being disgusted by strange produce, I felt the urge to purge after looking at a recent supermarket add, guess I won’t engage that morbid curiosity any time soon

  9. I grew potatoes for the first time this year and oh what a treat. Fingerlings and YG’s are so satisfying on the dinner plate. My Dad grew them to feed his large family. I grew them for the pleasure and satisfaction of them on the table. We are fortunate, in this time, to not have to depend on the garden to sustain us. If the crop fails there is always the market.

  10. No time this year to grow potatoes. Got some 10 lb deal at Safeway. Spuds were washed and ready to go.
    Support farmer’s that got it going on.

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