Originally Posted by
DrTimPerkins
The transition from above freezing to below freezing creates a vacuum in the wood which induces water uptake. If the freeze happens too quickly, water uptake will be incomplete.
During a warm spell if the trees are not tapped, there will be a pressure within the stem of the tree (proportional to the height of the tree above the point in question). This pressure develops naturally as a way for the tree to refill wood vessels that have cavitated (filled with air) during the winter. Vessels (pipes) that are filled with air don't work very well to transmit sap -- kind of like getting air into your plumbing at home....it reduces their functionality. The pressure serves to dissolve the gas into the liquid and "repair" the pipe to full functionality. Different tree species get rid of the air in different ways...maples do it by stem pressure. The sap does NOT go back into the soil...there is a structure in the roots (the 'endodermis') which prevents this from happening. Some of the water in the branches may transpire (evaporate out) through the bark, but this is only a relatively minor amount.
Hi Dr Tim,
I wondered if there are any ways to predict how long the trees will run sap during an extended warm
spell, like we have in central MA the last few days. It hasn’t been below freezing since Sunday I think, and sap still ran well in some trees yesterday. Today and tomorrow are still above freezing at night. Can trees keep running that long without a re freeze? I’m trying to forecast how much boiling I’ll be doing the rest of this week. Thank you.
2022 is season 7
2016: 20 taps on buckets, 4 gallons on a borrowed 2x3.
2017: 32 taps on buckets, 8 gallons of syrup, on a "loaner" Lapierre 19x48.
2018: 80 taps. First time tubing. New 10x12 sugar shack, Lapierre 2x5. Made 17 gallons
2019: 100 taps. 22 gallons. Added a small RO 50 gph.
2020: 145 taps, 30 gallons, sold half. Murphy cup is a great addition.
2021: tapped Feb 23, 150 taps, 35 gallons.
2022: 200 taps. I lost 50, added 100. Having fun but short season?