March 21, 2023 Sap Flow Report

Sap Flow Overview

Sap flows this week have been strong in the southern part of the province for those who tapped later, and slow for everyone else. In the southern region, there are signs that tapholes are closing, especially for those who tapped early. Bud swell has begun in both hard and soft maples. There is also a wide range of yield reported, most likely due to the different tapping times.

Further north and east in the coldest regions of the province, producers have barely begun collecting sap and a number are just getting tapped in this week. There is promising maple weather in the next week or two.

Taphole Reaming/Refreshing

I have received several questions from producers about the benefits of reaming or refreshing tapholes, especially those that have been in place since mid-January or early February.

The University of Vermont did some excellent studies on this and you can view an excellent overview of their research on taphole rejuvenation here. Essentially, there is a (non-statistically-significant) yield benefit of reaming an existing taphole wider and deeper later in the season; however, this practice will produce disproportionately more nonconductive wood in the tree. Taphole rejuvenation and re-tapping strategies are not recommended. I have attached some graphs from the presentation below to illustrate.

Most of you are inquiring about the scenario illustrated by the brown bar, which is essentially widening a hole that was drilled in spring at the “normal” time. In UVM’s study, this treatment produced 118% total syrup volume of the spring control, which is a hole that is drilled in spring at the normal time and which dries out “naturally” over the course of the season. (Keep in mind none of these numbers are absolute and universal figures. If we repeated this study where you are located, the numbers would almost certainly be different. What may be useful is looking at the relationship between the bars.)

Graph depicting total syrup yield as a % of spring control from 2018-2020. Different treatments are on the x axis and the total syrup volume as a % of spring control is on the y axis. Fall control yields 84%, fall ream and deep 97%, fall deeper 116%, fall second hold 103%, winter control 92%, winter ream and deep 120%, winter deeper 121%, and late-season ream 118% of the spring control, which is set at 100%.
Figure 1. Total syrup yield of different early tapping and taphole rejuvenation strategies.

Reaming the existing hole will produce a great deal more nonconductive wood than the control. Nonconductive wood is permanently plugged by the tree and no sap will flow through those cells again. Preserving sapwood is therefore a critical consideration for sustainable sugarbush management. The Where to Tap page gives a more detailed overview of this phenomenon.

Figure 2. Total stain volume of taphole rejuvenation or re-tapping strategies, compared to a 1-hole unrefreshed control. Source:

Reaming or refreshing tapholes, or even making new tapholes, is therefore not conducive to sustainable sugarbush management and operational longevity. This especially applies if you are a commercial maple syrup operation and either plan to produce in your sugarbush long-term, or if you use a sugarbush that has a long history of tapping. Again, taphole rejuvenation and re-tapping strategies are not recommended.

Links to research:

Early Tapping and Taphole Rejuvenation CDL 2021 Open House webinar

Wound Response to Taphole Rejuvenation Practices ( article)

Thanks to all who contributed their observations this week. I will send out another reminder to fill in the survey next Monday.

For the maple syrup production report below, find your region here.


Two producers in this region experienced excellent sap flows last Wednesday-Friday, but more are reporting that sap flow is slower this week than they would have expected given the weather. One producer drilled a fresh hole in a tree and found that sap was flowing well from the new hole, which is a good indication that the original tapholes are beginning to heal. One producer is considering pulling taps by the end of the week. Bud swell has been seen in soft maple and some hard maple, so it’s likely that the soft maple season will be done in the coming week, with a bit longer for sugar maple. Brix for hard maple sap was reported at 1.9-2.2 degrees, and soft maple at 1.7. Mostly golden and amber syrup are being made, with one report of dark syrup. Flavour is excellent with no filtration issues. Producers have made 60%-150% of an average year’s crop, and one producer has made over 200%.


Producers in this region are reporting similar sap flow to Southwestern, with slower flows than expected given the weather apart from last Wednesday to Friday. Some producers who tapped later are experiencing good flows, and are optimistic about the yield to come in the next few weeks. There is still a good snowpack in the woods. Sap Brix averaged 1.9-2 degrees, with amber syrup being made. Sugar sand is increasing for some producers but hasn’t yet affected filtration. Yield reports vary widely, likely due to the scattered first tappings throughout the season. Producers have made 25% to over 100% of an average year’s crop.

Grey-Bruce & District

Sap flow in this area was moderate, with some slow days and some great days. Sap Brix ranged from 2 to 2.4 degrees, and golden and amber and some dark syrup are being made. No filtration issues are being reported. A wide range of yields has also been reported from this district, ranging from 5% to 100%. Most producers are in the 15-65% range. Some folks are optimistic about the sugaring weather in the next few weeks, while others seem ready for it to be over!

Simcoe & District

Producers reported a few decent sap flows in the past week, but cold weather is keeping output slow in some bushes. Sap is reported at 2.2-3 degrees Brix, and golden and and amber syrup are being made. Several producers have notable quantities of sugar sand, making filtration difficult. Producers have made 20-80% of an average year’s crop.


Depending on location, some producers in this area experienced very good sap flow last Wednesday-Friday, while others had very little due to the cold weather. The number of boils this past week were limited, but those who did boil made golden and amber syrup. This weather of the coming week looks very good for sap flow. There is still lots of snow in many bushes. One producer has seen tree wells forming. Sap Brix is reported at 2.3-2.8. Those who have boiled are reporting some sugar sand but no filtration issues. Folks have made 5-40% of an average year’s crop.

Quinte & District

Most folks reported intermittent sap flows this week, with only one producer experiencing the best sap flows of the season. Brix ranged from 2.2-2.8, and mostly golden and amber syrup are bein made. Lots of sand is reported but it is filtering out easily. Folks have made 20 to 110% of an average year’s crop, with most around 50%.

Lanark & District

Sap flow reports range widely – from very slow to excellent in the past weekend and yesterday. Most sap reports range from 1.9-2.4% sugar content, but one producer on buckets reported 3.9%. Mostly amber syrup is being made, with some golden and some dark. Mostly minor filtration problems are reported, with one producer experiencing difficulties and some having no issues. Producers have made 10-30% of an average year’s crop. There is still significant snowpack in many sugar bushes.


Sap flows for this region were mostly slow early this week, and ramped up by the weekend. One producer reported harvesting 7L sap/tap on vacuum and just under 3L sap/tap on buckets. Sap Brix ranged from 2-2.9 degrees. Mostly amber syrup is being made, with some golden and dark and no filtration issues. Producers have made <5 to 20% of an average year’s yield. There is plenty of snow in the bush still.

Ottawa Valley District

A number of producers in this region began tapping this past week. One producer who was tapped earlier reports erratic flow. This producer measured 2.3 degrees sap Brix, making golden syrup. They also had issues with filtration, which is unusual for so early in the season. This producer has made 20% of an average year’s crop, while all other respondents remain at 0%.

Algonquin District

Respondents from this district unanimously reported no/low sap flow. One producer on buckets is just tapping this week. Sap Brix ranges from 2.2 to 3.2, with most reports clustering around 2.5. Mostly golden and amber syrup are being made, with some dark. Only one producer reported filtration issues. The majority of folks have made 0-10% of an average year’s crop, but two smaller bucket producers have made 25 and 50%.

Algoma & District

Sap flow in this region was low this week. One producer reported a light flow last Wed-Fri, but otherwise the cold weather has been hindering progress. Sap Brix ranges from 2 to 2.2, and amber and dark syrup are being made. Very few filtration issues. Like last week, producers are sitting at 0-20% of an average year’s yield.

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