Dispatch from the Sugarwoods, 3/24/20

As I write this, about 4 inches of fresh snow are glowing bluely in the predawn light.

The season continues for us. The mid-week freeze last week brought a nice color back to the syrup, and the flavor was as good as any we’d made all year. The warmth last Friday definitely took its toll – the sap flow has slowed. But it ran decent this past weekend; it even ran during Monday’s storm. “Sugar snow,” the old-timers called these March runs, when the thermometer hovers around 30°, and big wet snowflakes dapple and droop tree limbs, and defying all physics the sap flows anyway.

We’re at about ¾ of a crop, and it’s taken us 63 gallons of sap to make each gallon so far. As a comparison, last year was 51:1, which is closer to our long-term average. So things this year are significantly less sweet.

Why do trees vary in sugar content from year to year? There are so many variables that no one can say for sure. Two years ago our sugar content also averaged 63:1, and I decided then that it related to a drought in 2016, which produced a stress crop of seeds in 2017, which depleted the tree’s sugar reserves in the spring of 2018. Intuitively this kind of makes sense. You can test the starch reserves in a tree’s root system in the fall, and it’s documented that the reserves vary from year to year based on stress. (Testing of this sort is not standard practice in the industry – it’s mostly done in conjunction with an insect-related defoliating event, as it can give a sugarmaker an idea of tree health before the season so they can make the decision to tap or not.) You can read some work here from Harvard forest where they looked into the relationship between seed years and syrup yields.

We had a heavy seed year last summer, too. So maybe the same thing’s at play again. But I have a new theory this year I’m toying with, and it involves nighttime low temperatures. What we’re noticing, and it’s backed up by another producer I know with a high-vacuum system, is that when you spot check the sugar content of the sap after a hard freeze, it spikes up to 2-plus percent, where it should be. But then as days go by without a freeze, the sap gets progressively less sweet. If we look at the last two weeks, which were the heart of this season, we had a hard freeze (below 25°) on the 8th, followed by 6 nights where it either didn’t freeze or just touched freezing. If froze hard on the nights of the 15th and 16th, recharging the trees, but then it didn’t freeze hard again until the 22nd. So only three out of fourteen nights. When averaged, the low temperatures in that two-week window came out to 30.4°. Last year had consistently lower low temps. Nine of out fourteen nights in the 2-week heart of the season dropped below 25°, and the overall average was 26.7°.

So now I’m wondering if these middling low temps might be a contributing factor to the low sugar content as well. I talked with my friend Mark Isselhardt, the UVM extension maple specialist and a respected maple scientist, and asked his thoughts. He was buying the idea that the lack of hard freezes had an effect. He was skeptical of the seed theory.

Dispatch from the Sugarwoods, 3/17/20

The weather cooperated yesterday – the hard freeze in the morning felt like the sort of freeze you’d get in mid-February. The sap didn’t start running until around noon, which let us catch up a little. We acid washed the pans to remove the scale on the bottom. We canned and moved syrup which had backed up in the finishing pan.

We’re in this weird place, mentally, because the calendar and the cool weather says we should be in the thick of things, but our guts, and much of what we’re seeing outside, say the end is near. Last year we were just getting going in mid-March. But this winter and early spring have been very different. The snow’s gone here. The red maple and popple buds are bordering on breaking. There were reports last week of wood frogs in town. The syrup we’re making is still on flavor, but it’s very dark. The high temperatures forecast for Friday are in the 60s. It feels like early April.

There are always swings in where the season ends from year to year. Last year we ended on 4/7. The year before that on 4/4. The year before that on 4/2. The year before that on 3/26. The year before that on 4/14. The only time in our records that we’ve ever ended in mid-March was 2012, which was a truly bizarre year when late March felt like May.

And so we hold out hope. And we’ll wait and see.

Dispatch from the Sugarwoods – 3/13/20

It’s 4 a.m. on the 13th of March. A hard rain on the roof. The house is quiet otherwise, save for the woodstove – it ticks comfortingly as it heats up and the metal expands. I’m drinking coffee and building momentum to get out there again. A small radio in the kitchen had been broadcasting news about the COVID-19 microbe that’s terrorizing the world, but I shut it off to hear the rain and the woodstove ping.

The 1,600-gallon sap tank at the bottom of the hill will be close to overflowing; the 2,500-gallon tank across town probably already has. And it’s warm – too warm. The sap will soon begin to spoil. It looks clear when the weather is cold and the season is fresh. Then it goes to a sort of bluish-gray as ambient temperatures rise. When temperatures get above 60, the sap begins to look like watered-down milk. In the bottom of the tank there are handfuls of white precipitate – I suppose that gunk is yeast.

There’s so much to tell you about this season, and I will. But for now I’ll leave you with the idea that time is of the essence, and the image of milky sap. Microbial colonizers – harmless to humans but brutal to syrup quality – have inundated our sap collection system and their populations are exploding. In cool sap, microbial concentrations are less than 1,000/ml. In this weather, concentrations can be in the billions, or even trillions, per milliliter.

They feast.