Judge, jury and wine executioner…I mean enthusiast.

I received a desperate e-mail earlier this week — why was I no longer blogging? Had I fallen in a ditch? Turned to climate change denial? Dropped out of science writing and joined a convent?

No, nothing so dramatic. I just had jury duty. Actually, I still have jury duty. For weeks. And there is nothing that drains all of your creative juices as much as being sequestered into a stuffy courtroom listening to a case on…well, I can’t say what the case is on. I’m not allowed to talk about the case or where it is or who is involved or anything interesting. But I can tell you that jury duty can often involve a lot of waiting while lawyers and judges hash out information that the jury is not allowed to hear.

This leaves you, the juror, with a lot of extra time on your hands. You could start that new novel you’ve been planning, try to do some work, plan world domination. But the bailiff might return at any moment, in five minutes, in ten minutes, or three hours. You just don’t know. So what do you do for hours on end of continuously interrupted waiting? Puzzles! Large puzzles. 1,000 piece puzzles of things like clowns or flowers or puppies.

In my case it was a puzzle of Monticello, Thomas Jefferson’s house. So I had a lot of time to stare of TJ’s lovely estate — its brick facade, the gardens, the lush green yards. And as I pieced together the small windows on the second story of his manor, I contemplated not the house itself, but his vineyards or really the lack thereof.

There is much lore about good old Thomas Jefferson, but my favorite is his many failed attempts to grow wine grapes in the new world. As the story goes, he was supposedly never able to grow European stocks of wine grapes because they were susceptible to Phylloxera, a sapsucking insect that infiltrates the roots of grapevines in the US. American grapes are resistant to Phylloxera having had to contend with them for many years, but this was a new ailment to the alien European vines and they severely suffered.

You are probably thinking that this is all a little ridiculous; if we had American grape varieties, why bring over European varieties at all? Why not make wine from those well-adapted American grapes? What were early Americans, total snobs or something?

It turns out that American grapes are just fine for eating, but they make a foxy wine – and I don’t mean this kind, I mean a foxy flavor. What is a foxy flavor? I have no idea, but apparently it’s a thing with wines, and American grapes make wines that are much like American women…foxy as hell!

Finally grape growers in America figured out that you could just graft the European vines onto American rootstock and avoid the Phylloxera trap all together. In fact, American fruit growers in general have done a pretty valiant job of identifying pests and using all sorts of tools to manage these little critters. From grafting to planting cover crops to conventional pesticide-use to integrated-pest-management to organics to GMOs to crop rotation; there isn’t anything farmers won’t try to manage the many pests that can come in and mangle their crops.

Independent of your opinion on how they do it, they have certainly done an amazing job of keeping those pests at bay given the sheer amount of produce available to us in grocery stores across the US. All of this could be greatly disrupted though by climate change as the temperature heats up (1), but probably not necessarily in the way that you think.

When most of us think about warmer temperature, we think about summer heat and wildfires and droughts. Sometimes we also talk about snow and lack thereof, or sometimes an overabundance of snow, because that is related as well. But we don’t really talk about winter weather in terms of its usefulness in killing insects, and keeping their populations down.

Winter, though, really icy, terribly bitter cold winters, are an important part of insect control, and there is nothing some insects love more than a nice, cozy unseasonably warm winter that they can just snooze right through. One excellent example for wine-grapes is the bitterly-hated glassy winged-sharpshooter (I didn’t make that name up, I promise). The sharpshooter is a vector that carries this gnarly bacteria to the vines resulting in something called Pierce’s disease(2).

Not only will the sharp-shooter enjoy a warmer winter, because hey, who doesn’t love a warm and mild winter? But, as temperature increases, the ability to pass on the disease from the sharpshooter goes up (3). So higher temperature means more disease transmission. Bad news for the vines, great news for the pathogen.

Can you imagine if warmer weather meant higher disease transmission for people? Well…sometimes it does…on Spring break, I guess….but that’s sort of different….

So as the climate continues to change, there will be a whole new host of challenges that growers will have to contend with. Just as farmers had started to figure out all the intricacies of protecting their crops from insects, people had to go and make things climatically interesting, and a little extra challenging for the farmers. Who knows, maybe in 100 years the terrain that farmers are dealing with will be as foreign to them due to climate change as the Phylloxera-infested land that Thomas Jefferson had to deal with.

Will we be as crafty then as we’ve been since Jefferson planted his first vineyard at Monticello? Maybe it will be for someone 100 years from now to contemplate as they sit in a court house waiting to be called in for jury duty. When it comes to climate change though, time, not people, will be the judge.

Further Reading

(1) A review of the potential climate change impacton insect populations – general and agricultural aspects
(2) Climate change associated effects on grape and wine quality and production
(3) Temperature mediates vector transmission efficiency: inoculum supply and plant infection dynamics

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