On seed potatoes
A month ago, I set myself up to do a real garden this year (Post #580). Let me dub that my pandemic garden. And now, as we pass our probable last-frost dates, it’s put-up-or-shut-up time. Get off my duff, get the soil prepared, get the seeds sprouting or in the ground. Or admit that I’m just a nervous Nellie with no follow-through.
I’ve decided to talk about my experiences, trying to get back into gardening. Figuring that if I can do this, anybody can. You name a crop that can plausibly be grown in Northern Virginia, and I’ve failed at it.
But, oddly enough, a couple of the earliest steps reminded me of a couple of things I learned as an economist. So I thought I might get the ball rolling with a post on seed potatoes, and, next, the hog-slaughter cycle.
Seed potatoes: Sprout inhibitor and viral plant diseases
One of the first things to go into the ground in the spring are the potatoes. Mine should have been in the ground a couple of weeks ago, but I’m still awaiting delivery of my seed potatoes.
For those of you who have never grown potatoes, you take a “seed potato” and cut it into little chunks, where each chunk has an eye. So one good-sized potato serves as seed for several new potato plants. A reasonable expectation of yield is that each pound of seed potatoes yields about 10 pound of potatoes at harvest.
Most people realize that using grocery-store potatoes as seed potatoes often fails. Those are treated with one of a range of chemicals to inhibit sprouting. Some of those sprout-inhibitors thoroughly destroy the potato’s ability to grow normally by damaging basic processes such as DNA synthesis. They cannot effectively be washed off. Depending on the dose that the potato got, the effects can range from complete suppression of sprouting to potatoes that appear to grow well, but produce malformed, knobby tubers.
It’s not clear that potatoes labeled as “organic” potatoes are or are not so treated. When I read the rules regarding what may and may not be used in organic vegetable production, the only substance that might be used as a sprout inhibitor that appears on the list is ethylene gas. And that’s mentioned only for use with citrus and pineapple ripening. So, by “the rules”, you’d have to say no.
But I note that the “organic” Yukon Golds currently on my counter top certainly behave as if they were treated. They now have tiny sprouts that blacken and die off if they grow beyond a quarter-inch or so. That suggests that some long-lived treatment has been applied. At this late date, they’d be sprouting by now if they hadn’t been treated in some fashion.
The consensus of internet opinion is that potatoes from a farmers’ market are unlikely to have been treated with sprout inhibitors. The ones I got at the Holy Comforter famers’ market two weeks back follow that rule: They are sprouting vigorously, with no sign of die-back.
So, for the time being, I’m planting farmers’ market potatoes, as I wait to see whether my seed potato supplier will come through.
But there’s a second reason to use certified seed potatoes: viral plant diseases. Potatoes are subject to a wide variety of crippling viral diseases, and potatoes sold as seed potatoes have to be certified virus-free, or at least, certified as to minimal viral content. Not only can these disease kill the current crop, as with many plant disease, the potato virus can remain in the soil for a few years, rendering fields useless for potato production for some period of time after infection.
In Virginia, the Seed Potato Board (yep, that’s a real thing) regulates standards and trade in seed potatoes, for commercial growers in the state. In other states, it may be literally illegal for the home owner to plant grocery-store potatoes, for fear of spreading viral potato diseases. But as far as I can tell, it is not illegal for a non-commercial farmer to plant non-certified potatoes in Virginia. Either way, once certified as virus-free, seed potatoes can be planted anywhere in the Virginia, by commercial and non-commercial farmers alike.
I’m taking a gamble, as I could not get my hands on seed potatoes. Because I rarely grow potatoes, that seems like a reasonable choice.
A seed potato analogy.
I read the other day that an estimate 4 percent of LA county residents test positive for antibodies to COVID-19. That’s consistent with a separate estimate of about 2 percent in a different California county, using a different methodology. And estimates that the majority of younger individuals will be asymptomatic or mildly symptomatic upon infection.
As we re-open the economy, we need to start thinking of those people as the seed potatoes of this pandemic. All minor doubts aside, a) those people are almost certainly virus-free, and b) they are probably unable to be re-infected.
There are some doubts about the latter, but I think they have been overblown. Those mostly arise from Korea, where a few tens of individuals (out of a recovered population of 8000+) tested negative for coronavirus subsequently returned to positive status. They claim that’s evidence of re-infection. I think that’s far more likely due to a small false-negative rate in their testing regimen.
Korea uses two negative tests, 24 hours apart, to determine whether hospitalized individuals are virus-free. And so far, out of about 8000 recovered patients, a few tens of those that passed that test have gone on (typically one day later) to have a third test that was positive.
To me, that looks like the two-negative-test regimen has a few false negatives. That is, out of 8000 tested, a few have shown two negatives, 24 hours apart, while not actually being negative for the virus. Korea steadfastly maintains that their testing regimen is perfect, and so claim that the subsequent positive test is a result of re-infection. I think it’s vastly more plausible that their regimen has a roughly 1% false-negative rate. For almost any other lab test I can think of, a false negative rate that low would be an outstanding achievement. And so, immediate re-infection cannot be ruled out, but that would make this virus almost unique in that regard, and I think that a small false-negative rate is by far the more likely explanation of those facts.
When in doubt, just ask yourself why they require two negative tests, 24 hours apart? Why not just one. The most likely answer has to be to reduce the false negative rate. If each test separately had a 10% false negative rate, the two together would have just a 1% false negative rate. I can only assume they require two tests to bring that combined false-negative rate down to an acceptable level. And I could easily see them not admitting that publicly as a way to avoid public lack-of-confidence in their widespread testing regime.
We should start thinking of those coronavirus seriopositives as the seed potatoes for restarting the economy.
First, and most directly, they can provide convalescent plasma. With that technique, someone who has survived coronavirus donates blood, which then provides coronavirus antibodies to the recipient of that blood. That’s an old, old technique for dealing with infectious disease outbreaks. It’s one of those treatments that worked well in the past, has been used recently for uncurable viral diseases such as Ebola, should work now, and has been shown go work extremely well in a small-scale trial (in China).
And, much like the seed potato, one plasma donor can provide enough blood for several other individuals. The Chinese example (search this website for details) was based on a 200 ml infusion of plasma. At that rate, a standard one-pint blood donation provides enough for at least two recipients. More, if an individual makes several donations.
But the other aspect that is seed-potato-like is that these individuals should be free to go anywhere, and engage in any activity. They are like the potatoes approved by the Virginia Seed Potato Board. The should be able to be used anywhere. Coronavirus restrictions should not apply to them. In theory, they’ve had it, they’re over it, they’re probably not spreading it, and they probably can’t get it again.
The government ought to issue them clip-on IDs, and as long as they are wearing those and they are visible, no coronavirus restrictions should apply to them.
Among other things, I bet these individuals would be highly valued as public-facing employees in essential businesses. Given the rate of unemployement, and the (apparently) high percent of the population that could serve as our economy-reopening seed potatoes, I think this idea deserves some attention.
The end-game of this is to have the entire population in that state, but by artificial means (vaccine) rather than by natural immunity (by surviving the disease). I really don’t see the downside to starting that now.
As an economist, I’ll even go one further. Suppose you are young and unemployed. Suppose you realize your odds of dying from coronavirus are quite low. Supposed you’d be willing to risk that, in order to graduate to post-infection “seed potato” status, so that you could be free of coronavirus restrictions and go back to work.
In that case, if we’re so fired-up to get the economy re-started, why not arrange sites that would allow such low-risk individuals to choose to be exposed to coronavirus and placed in quarantine? Those that are infected and survive to a virus-free state would be issued their “seed potato” IDs, and then lead the re-opening of the economy.
Many of you will be appalled by that idea. But please refrain from judging me until you read the next post.
I have to get back to real gardening now.
Christopher Hogan, Ph.D., chogan@directresearch.com
