Unusually warm weather affecting Michigan maple syrup season

Winter’s unusually warm temperatures have caused sap in maple trees to run earlier than usual. Producers are concerned about tapping early and hope severe winter weather does not return to Michigan for a prolonged period after starting the tapping process.

The unusually warm temperatures that many areas of Michigan have been experiencing this winter has caused the maple syrup season to start much earlier than expected – which has caught some producers off guard.  Typically, the maple syrup season starts in the southern Lower Peninsula in mid- to late-February and proceeds northward until reaching the Upper Peninsula after eight to 10 weeks.  So starting the season in the first week of February (as some producers have) is cause for concern.  While the thermometer says it’s time to tap, producers have been reluctant to start too early for fear that winter will return for a prolonged period after tapping.

The danger in tapping too early is that the tap hole might “dry out” while there’s still sap to collect in late February or March.  Tap holes generally “dry up” because micro-organisms grow inside the tap hole (wood) surfaces during the course of the sap season and clog up the vessels in the tree through which sap flows. It is possible to re-bore the tap holes with a larger diameter drill bit in order to cut through that layer of blockage and to get the sap flowing again.  However, it’s something commercial operators do not want to do as it drastically increases labor costs and makes a bigger hole that must heal before the next syrup season.

Maple sap runs best when it freezes at night (e.g. in the high 20-degrees Farenheit range) and then warms up above freezing the next day (in the range of 40-degrees Farenheit and hotter).  If it stays warm at night and warm during the day or if it freezes at night but barely goes above freezing the next day, sap does not flow as well or hardly at all.

The other danger of a too quick warm-up is the effect on maple tree bud development as it begins to break out of winter dormancy. Unfortunately, once maple tree buds begin to swell and break open, the sweet-tasting maple sap turns into a green and bitter-tasting sap (called buddy-flavor) that results from chemical changes inside the sap of the tree.  Even if the weather returns to the “normal” freeze-thaw temperatures that encourage sap flow, the sap will not go back to its sweet taste, instead staying buddy flavored.  Boiling down buddy-flavored sap will only concentrate the off-taste and result in bitter-tasting maple syrup that cannot be sold to consumers.

Typically, the earliest sap runs of the season produce the more desirable— and in some states more expensive— lighter, golden-color syrup.  As the season progresses, temperatures warm even more, snow cover disappears and the tree is in danger of budding out.  All of this means sap can’t be kept as fresh as before and the chemicals in sap begin to increase - which means batches of syrup start coming out darker than before.

While darker syrup is usually considered lower grade it can taste just fine, but capturing early sap is always most desirable. Plus, as unpredictable as the weather is you want capture what you can, while you can in case the season comes to a quick end.

While it’s too early to predict the outcome of the 2012 maple syrup season in Michigan, the maple syrup industry has experienced poor yielding maple syrup seasons before in the state. In 2000, the maple syrup season was terribly brief.  It warmed up quickly and stayed warm enough that maple trees budded out early and the season was over very quickly.  That year, Michigan produced about 44,000 gallons of maple syrup statewide as compared to its annual average of about 75,000 to 80,000 gallons. For a good maple syrup season, it’s all about the right weather (i.e. experiencing diurnal freeze-thaw cycles called sap runs).  However, sometimes it seems that maple syrup producers are more at the vagaries of the weather than any other types of farmers.

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