Improving profits for maple producers through tubing sanitation

Data for the primary study comparing sap yields from spout/dropline replacement and cleaning were collected over the 2014 and 2015 seasons.  Technical issues precluded repeating the main study in 2016, however ancillary research data was collected during the 2016 and 2017.  In general, replacement strategies (spout replacement, use of Check-valve spouts or adapters, or dropline replacement) produced the highest sap yields and higher net profits (gross profits minus costs of strategy implementation).  Cleaning methods produced an intermediate level of net profit.  Cleaning with spout replacement resulted in the lowest net profit due to higher costs.  None of the chemical sanitizers tested were clearly more advantageous than the others in terms of efficacy, however cleaning results were greatly improved with longer contact time between the sanitizer and the material being cleaned.  However, the amount of sanitizer, the time required to complete cleaning, and the necessity to rinse after cleaning meant that most cleaning treatments were frequently not cost-effective when compared to simple replacement strategies. Short-contact time cleaning strategies such as sucking in a small amount of sanitizer under vacuum were considerably less effective due to inadequate sanitizer contact time, therefore producing reduced yields and lower net profit.

Throughout the course of this project, a total of 124 individual presentations were conducted within the NESARE region, resulting in 4,815 producer contacts (including repeat attendees), and 152 hours of instruction into methods to improve sanitation of maple tubing systems and achieve higher net profits.  In addition, eight individual publications were made in maple producer journals or newsletters, and a video was produced.  

Although not part of the original project, the introduction and adoption of 3/16″ tubing during the time of the project period resulted in the investigators doing additional research work to examine the effects of sanitation practices with this tubing and communicate those results to maple producers.  This research builds upon and extends the NESARE sanitation study.  Early results indicate that 3/16″ tubing is more susceptible to sanitation-induced sap yield losses over time.  Work to determine the most appropriate remediation approach in 3/16″ tubing systems is still ongoing.

Introduction:

Sanitation is a critically important component of achieving high yields from maple trees.  A multi-year field study across two sites (NY and VT) was used to examine the impact of various replacement and cleaning strategies of spouts and droplines on sap yield and net profit (gross profit from sap collected minus the cost of implementing the sanitation strategy) and to recommend approaches maple producers could take to achieve their desired objective.  The information gained in this study was communicated to maple producers via presentations at meetings and conferences, through publications in maple industry journals and newsletters, and in an online video.  A majority of producers adopted one or more recommended strategy to increase their sap yields and net profits.

Annual sap yields in most maple operations are reduced by 10% or more annually due to microbial contamination of the tubing collection system (1). Microbes present in the system infect the new taphole and accelerate the rate of taphole drying, the slowdown and cessation of sapflow (2). Consequently, these yield losses result in significant reductions in net profits of maple operations. To counter taphole drying, maple producers employ two general types of sanitation strategies: cleaning/sanitizing the tubing system after each production season, or annual replacement of various parts of the tubing and spout system. 

Replacement strategies are aimed at improving sanitation in the immediate vicinity of the taphole by replacing system components such as spouts or droplines. This has been shown to result in sap yield and net profit increases ranging from $1.02 to $3.09 per tap (3-5). Cleaning/sanitizing (“cleaning”) strategies are aimed at reducing microbial populations throughout the tubing system by washing, which is attempted through a variety of methods (such as pressurized air and water rinsing), and/or by rinsing the system with food-grade sanitizers such as bleach or alcohol. However, the effectiveness, if any, of cleaning strategies in bolstering sap yields and net profits is unknown.  

A 2011 survey of 178 maple producers conducted by UVM PMRC indicates that 89% of producers in New England and New York with operations of all sizes annually clean their tubing systems (6). However, it is possible that many of the currently used cleaning strategies either do not result in profit increases comparable to those of replacement strategies, or may even actually result in net profit losses (due to cost of materials and labor required  to clean). Thus many producers – up to 89% of the over 4,000 producers who tap 7.8 million trees in NE/NY (7,8) – are likely not using a strategy that successfully combats yield losses from microbial contamination and results in the best possible outcome (the largest increase in annual profits). This means that the majority of maple producers could significantly increase their net profits, by at least $1-3 per tap annually, by adopting a more beneficial strategy.