On April 12, 2020. the snow was gone, but it was still freezing at night and the sap was running. The weather forecast for the next 10 days indicated more freezing nights but very warm days, as high as 14°C. We looked at the buds on the trees and listened for spring peepers down by the stream. These are signs that the season is nearing its end.
If it gets too warm, we pull the taps and stop collecting sap even it it could run for another week or two. Sap collected too late in the season makes maple syrup taste like burnt industrial chocolate with a lingering unpleasant aftertaste. That defect is called buddy, named for the buds that start to turn red and fat just before they open into leaves. The flavor isn't from the buds. That is just how we know when to stop.
Buddy syrup flavor actually comes from leaves on the ground from last season. They decay and release nitrogen and sulphur, which seep slowly into the ground. As those elements permeate the roots and into the sap, syrup quality drops from excellent to acceptable, and then down to defective.
We stop collecting sap while we are still making excellent syrup. There is no point to make anything that we are not proud of, that does not represent our craftsmanship, passion, and desire to make people happy when they taste our syrup.