How do maple producers collect sap?

For years, maple producers hung buckets on trees, and allowed the sap to drip into the buckets. Collecting the sap from hundreds, or even thousands, of buckets and transporting it to the sugar house was very hard work. In the 1950’s, maple producers experimented with a new way of collecting sap. They attached a plastic tube to each tree, which then led to a central collection container or tank (you can see the tubes in this photograph).

In the 1960’s, producers and scientists asked whether creating suction (or vacuum) on the tubes might allow them to collect more sap without harming the tree. They found that applying suction at the rate of 10 inches of Hg (Hg stands for mercury, a way of measuring the amount of vacuum) caused a 50% increase in the amount of sap per tap. Applying 15 in. Hg nearly doubled the production per tap. At 20 in. Hg, there was no further advantage over 15 in. Hg.

Trees have been tapped for over 25 years using vacuum tubing with no apparent damage to the tree. For more information visit the virtual tour on sap collection.