Production of maple syrup and mushrooms

May 26, 2018

During our recent visit to the Bas-St-Laurent and Témiscouata regions, maple syrup producers informed us that maple syrup production was one-third of what it had been in previous years.For a good maple syrup harvest, two conditions are required:

-Favourable conditions for casting: nights under the freezing point and day temperature above the freezing point, without being too hot.

-The summer before the harvest should be favourable for the growth of the trees with good sunshine and regular rains maintaining a good level of water in the soil, the same conditions as those required to have a beautiful garden.

The syrup sugars are produced in the maple foliage during July and August; these sugars are accumulated in their roots throughout the summer. It is these sugars that go up in the trunks during the next spring to grow the foliage, add a new wooden ring to the trunk and give a sap flow to produce syrup.

During our visit, we receive several questions about the very disappointing harvest of spring 2018. However, during the summer of 2017, Témiscouata and Bas-St-Laurent experienced an exceptional drought that lasted until September, which greatly affected farmers in the production of fodder and grain. It is the same for maple trees; if forage production is good, we can expect a good maple syrup production the following spring. In the spring of 2018, maples could not give what they did not have. If we superimposed a map of poor crop yields in 2017 to a map of poor yields in maple syrup production in 2018, there would most likely be a strong correlation. The buds of the leaves are also formed during July and August. The poor conditions of the summer of 2017 will make the foliage of 2018 less luxuriant, resulting in lower sugar production, which will affect the  2019 production, which likely will be lower than average. Concerning the accumulation of reserves and the rise of the sap, we must consider the following factors:

- It is known that plants and trees accumulate in their roots significant reserves of nutrients for the coming season; the rise of the sap in the trunks is also made possible thanks to these two factors.

- The sap freezes (or thaws) at a temperature below the freezing point, which allows it to circulate in the wood tubes, even if the soil around the roots at the surface is still below the freezing point.

- In spring, the ground thaws partly thanks to the heat rising from the centre of the earth; thus, the deep thaw of the soil often starts before the surface thaw. In some places, this heat input from the centre of the earth is large enough that the soil never freezes.

The fruiting of forest fungi follows precisely the same pattern. Not only there is no fructification a year of drought, but the following years will see a weaker fructification, because mushrooms associated with tree roots must accumulate reserves, often over several years, to give abundant fruiting.

 Fernand Miron, biologist