Welcome to the Ontario Maple Syrup Production Report for the 2019 sap harvest and syrup processing season.   The report will be posted once every two weeks and will continue throughout the syrup processing season.  Each message will include a summary of sap flow activity across the province, progress on syrup processing and crop yield, and highlights from producers on syrup colour class and syrup flavours as the season advances.

Tapping maple trees

The extended weather forecast indicates that thawing conditions will occur this coming weekend and may be suitable for installing taps in trees.  However, a sharp drop in temperature to deep freezing conditions will occur late in the weekend and will continue throughout much of the coming week.  Sap collected and not processed during the thawing conditions will freeze solid and remain frozen until the next thaw.  Producers with medium to large operations may decide to delay most of their tapping until after the forecasted deep freeze.

Strong potentially damaging wind is also forecast and may cause limb breakage and damage to sap collection tubing in the sugar bush.  Producers can be prepared for tubing repair if damage by limb breakage occurs.  Trees are more brittle and less flexible during winter due to their dehydrated dormant state, more susceptible to wind damage.

In early regions of southwestern Ontario where tapping is already underway or completed, sap will likely flow during the weekend.  Sap collected can be processed quickly into syrup prior to the expected deep freeze.  Sap that is frozen in storage tanks will remain in good condition, but it may be awhile before the next thaw.

Many producers utilize the first good flow of sap to rinse and clean vacuum tubing systems prior to collecting sap for processing.  The first good flow of sap is sometimes naturally off-flavour anyway, and can produce syrup that has an off-flavour that is described as ‘tree metabolism’.  Normally by the second sap flow, the metabolism off-flavour is purged out of the trees and good sap flow begins.

Drain sap and water from any processing equipment, reverse osmosis units, transfer tubing or sap storage equipment that could be damaged by expanding ice if frozen solid.

Trees that are frozen and where air temperatures are below – 5 ⁰C should not be drilled and tapped. Installing taps into frozen wood can cause splitting of the bark and xylem tissue above and below the tap hole.  Splitting will cause sap to leak down the tree instead of flowing into the spile.  Split bark and wood creates far more injury to the trees compared to proper tap holes.  Split bark requires an extra expenditure of energy by the trees to heal in spring once new growth commences.   For best results, tap trees only when they are in a thawed condition, near or above 0 ⁰C.

Sustainable tapping guidelines

The final decision on when and how maple trees are tapped resides with each producer. Long-term research and industry experience provide the following guidelines for tapping a sugar bush based on tree diameter.  The guideline applies only to sugar bushes that are in a healthy condition and have not been subjected to recent natural or induced stress.

*Many producers using modern vacuum tubing for sap harvest install no more than one tap per tree.  Limiting taps to one per tree each year significantly preserves healthy sapwood for future harvests.

Reduced tapping on stressed trees

The health of the sugar bush should be given top priority when decisions are made on tapping.  Maple trees that are under stress due to moderate to severe defoliation by insect pests during the 2018 spring and summer will benefit from reduced tapping or no tapping during the 2019 sap harvest.

Larvae of forest tent caterpillar, Gypsy moth and spring cankerworm caused severe defoliation in various locations last year and affected trees will benefit from reduced tapping this season.  Sap that is harvested from trees that were severely defoliated in June and July 2018 will have significantly reduced levels of sucrose sugar for one to two years.  The sugar may best be left for the trees to utilize for their recovery this spring.

Other causes of stress in sugar bushes include; excessive tapping practices, limb breakage due to high winds or heavy ice accumulation, nutrient deficiency in soil, for example, low calcium and magnesium levels in acidified soil on the Canadian Shield, drought, flooding.