Author: Jeremy Cherfas

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Getting to the bottom of potato late blight resistance

There’s a bit of an argy-bargy developing in the comments to Robert’s provocative post Inorganic farming. Anastasia raised the question of transgenics for fungal resistance, which Robert echoed. Patrick then waded in bullishly to ask why transgenics were needed, when breeder Tom Wagner “has created quite a number of potato lines totally resistant to late blight”. And that created a clamour from Robert to the effect that he couldn’t find any evidence of Wagner’s success on this front.

Two points.

First, although Patrick was perhaps too modest to say so, he has arranged for Tom Wagner to be at a meeting in Oxford, England, as part of a Greater European Tour that Tom is undertaking in the autumn. So anyone who wants to know about his selections for late blight resistance can get it straight from the horse’s mouth. And report it here, please.

Secondly, don’t panic. Scientists at the University of Dundee in Scotland and elsewhere have discovered a single gene that, they say, is the key to blight resistance. “We are really excited by the discovery of RXLR. This has provided a signature to search for proteins that are delivered inside host cells, where they may be exposed to plant defence surveillance systems,” said Professor Paul Birch, the team leader. Clearly it won’t be long before the threat of late blight is a thing of the past.

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Featured: Blight

Robert asks the tough questions:

If there is demand for a diverse set of resistant and tasty varieties, and “there’s a lot available” why don’t breeders and seed companies supply? No demand? Too expensive? All in cahoots with Big Chemicals?

I think we need some in-depth research to tell us how large the “demand for diversity” pimple is on the rump of “big breeding”.

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The salad in winter

It’s a common misconception that all plants that enjoy heat need heat to survive. Anastasia says as much when she “goes out on a limb” to suggest that spinach won’t survive at -40°F, and then conflates spinach in winter with tomatoes in winter. I’m going to abuse proprietorship to point out both that spinach is a cool-weather crop — despite what they do to it in California — and that it doesn’t need to be growing in order to be freshly available year round, although I concede that -40°F is probably pushing it somewhat. (Who would want a salad under those conditions anyway?)

Many plants, and spinach is a prime example, can survive freezing. They do so even better if they are primed by exposure to cold temperatures before the freeze hits, which is the natural way of things. If you sow spinach in late summer, and let it get to be a good size before hard winter arrives, it will survive reasonably well given minimal protection in the form of a cold frame or a polytunnel. And it will be ready to grow away again as soon as temperatures start to warm up again in the spring. Not just spinach either: the list is long.

This idea, of growing plants in the autumn and protecting them for harvest through the winter and an early start in spring, is nothing new. Victorian gardeners were past masters. In modern times it is most closely associated with the name of Eliot Coleman. As it happens, he prefers organic methods, but don’t let that put you off. His book is wonderfully practical and there’s a bit more background here.

And of course there’s more to leafy-greens-that-aren’t-lettuce than spinach, but surely I don’t need to belabour that point here. My conclusion is that while it takes planning and foresight, it is perfectly possible to have access to a local diverse diet in cold winters.

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Pssst! Wanna pollinate pumpkins?

I was cleaning out a mailbox the other day, and came across a message from Karl Haro von Mogel, who is quite well known around these parts. He was advising me that his new pollination video — on Cucurbits — had just been uploaded to YouTube. And I forgot to write about it. Apologies to Karl, but I’ll make it up in a minute.

The video is clearly aimed at the more industrial end of the spectrum. Bringing parent plants into a greenhouse was never an option for me. On the other hand, wandering through the pumpkin patch soon after dawn to gather ripe male flowers that had not quite opened was one of the great treats of saving my own seeds. And Karl deals with more than just controlled pollination. The first 3 1/2 minutes gives a good overview of cucurbit diversity, centres of origin and wild relatives. And near the end he reveals the secrets of the seedless watermelon. All in all, well worth 10 minutes of your life, even if you plan never to pollinate a pumpkin.

In his email Karl mentioned that he had entered the video for a competition at Chlorofilms. It was one of 17 2nd prize winners. So were some of his other films, including this one on pepper breeding.

Maybe if we could rustle up “at least $8000” in prize money we’d get some entries to our own competitions. Or maybe we should just enter the next Chlorofilms competition, if and when it happens.