Sap flow and syrup processing update

A few maple syrup producers in early areas of Southwestern Ontario and Prince Edward County have completed tapping their sugar bush now, many are in the process of installing taps.  One or two sap flows are reported earlier this week and new syrup has been processed .  The sap sugar content ranges from 2.0 to 2.5 ⁰Brix and appears to be starting higher than average.  Later regions have also begun tapping trees.

Remember not to drill tap holes or install spiles while tree trunks are frozen below -5 ⁰C.  Wait until thawing conditions allow safe tapping.  The forecast days ahead will be ideal tapping weather in many southern areas.  Forecast conditions may not be cold enough at night to induce heavy sap flow however, for producers who are tapped and ready, some sap can be expected to run.  Hopefully the warm spell won’t last long.

Many producers discard the first significant sap run because of potential off-flavours in syrup that frequently occurs in the first sap.  The discarded sap will also serve to effectively rinse vacuum tubing before larger volumes of sap begins to flow.

It is not possible to predict what the approaching syrup season will be like in any given year. The results will be known for sure by the end of April.  The long drought that occurred last summer in most southern Ontario regions suggests that the maple trees will not contain as much stored starch and sugar, compared to a summer having normal precipitation.  Sugar bushes that were affected by drought and by excessive defoliation from Eastern Tent Caterpillar larvae or by Gypsy Moth larvae population upsurge will be stressed to various amounts.  It is a good idea to be extra gentle with the sugar bush this year.

Tapping guidelines

The following tapping guidelines have been developed by maple researchers and industry leaders and are based on the health status of sugar bush trees, site quality and average annual wood growth.  Since the trees endured a long summer drought in 2016, conservative tapping is recommended.  Trees that also endured significant defoliation by Eastern Tent Caterpillar or Gypsy Moth can be considered low in energy level.

The final decision on how trees are tapped for sap harvest is the responsibility of each producer.  New vacuum tube technology and resulting high sap yield has helped reduce the temptation to over-tap trees in the sugar bush.

Managing a sugar bush

The long-term health of a sugar bush will be significantly improved where regular monitoring and visual inspections can identify defective trees that can be removed as the need arises.  Removing problem trees at convenient times will free up space in the canopy and in the soil to allow better quality crop trees to grow as the future sugar bush.

Defective trees

A top priority should be to protect regenerating seedling and sapling trees from logging activities.  Older trees can be marked for removal due to infection by naturally occurring diseases, insect pests, injury to trunks from previous logging activities or breakage and weakening of trees by ice storms and high winds.

Be careful not to remove too many trees in one operation, no more than one-third of the basal area, including all ages and sizes of trees.  Over-harvesting could leave the sugar bush vulnerable to wind damage or allow invasive weeds and shrubs to invade the bush due to excessive sunlight, such as buckthorn.  If in doubt, seek advice from knowledgeable forest or sugar bush industry workers.

It is important to be able to identify symptoms of maple tree diseases and other defects.  Most of the following photos are graciously provided by Laurie Thompson RPF, Forestry Professor at Sault College, Ontario.

Thinning

As young trees grow, they can become overcrowded within an area, which can severely slow the growth of competing future trees.  Periodic marking and thinning of the sugar bush will release the best trees, that is, give the remaining trees more space for roots and canopies to grow, by systematically removing a percentage of the competing trees every few years.