Sapling sugar maple (Acer saccharum Marsh.) trees were defoliated artificially at 10-day intervals beginning May 27 and ending August 5, 1981. Refoliation, terminal bud and shoot development, and xylem starch and sap sugar concentration were observed in defoliated and control trees. All defoliated trees refoliated, but decreasingly with later defoliation. Defoliation caused an acceleration in the rate of primordia initiation in terminal shoot apices. After early season defoliations, the developing buds in the axils of the removed leaves abscissed, but axillary and terminal buds on the refoliated terminal shoots survived through winter. In late season defoliation, most buds of refoliated shoots did not survive and the next year’s growth depended on axillary buds formed prior to defoliation. Thus, when progressing from early to late defoliations, the next year’s shoot growth depended decreasingly on the last-formed and increasingly on the first-formed portions of the previous year’s shoot. Early October starch concentration in xylem decreased with later defoliation and was nearly absent in shoots and roots of trees defoliated in late July. There was not, however, a corresponding decrease in sap sugar concentration. Mortality occurred only in late defoliated trees and was associated with starch depletion.
Showing 341 – 350 of 361 resources
The advent of plastic tubing systems to collect sap has eliminated several problems associated with the traditional bucket system. However, plastic tubing systems also present some problems of their own. Sap quality problems arise if the lines sag and the sap lingers within the tubings or the large conduits. In addition, the warming effect of the sun increases the tem perature within the tubing to optimum levels for microbial growth and sap flow may decrease because of “organic buildup” on the internal tubing walls. This buildup is a result of the adhesion of microorganisms to the tubing walls.
In March and April 1983, 289 and 196 young grafted sugar maple trees were tapped and evaluated for sap-sugar content. In April, sap was collected from taps both above and below the graft union. Diameter of all tapped trees at 18 inches above the ground was measured. Analysis of the data revealed that: (1) trees selected for high sugar yield cannot be reproduced by grafting on rootstock of unknown but varying sugar content without encountering large fluctuations in sap sweetness of the trees produced; (2) diameter is not correlated with sap sweetness of young grafted trees; (3) numerous sap-sugar readings over time may be necessary to identify the sap sugar characteristics of a candidate sweet tree; and (4) the cause of the variation in sap-sugar content of trees over time needs to be investigated more fully.
Our objectives were to develop time series of maple production costs and to observe the effects of changing technology, fuel price, interest rate, and sap sugar content on production cost. In addition, the relationships between major production cost items were examined.
A study of how sap moves in maple trees
The purpose of this chapter is to describe a conceptual framework for understanding how trees grow and how they and other perennial plants defend themselves. The concept of compartmentalization has developed over many years, a synthesis of ideas from a number of investigators. It is founded on observations of trees injured in the field by wind, snow, ice, fire, animals, and insects, as well as during pruning, coppicing, sugaring, and other forest and orchard management practices. It is based on experimental studies of natural and artificial wounds with and without controlled inoculations with selected pathogenic and saprophytic microorganisms.
We initiated a controlled test of the effect of in-line UV light on the microorganisms in free-flowing sugar maple sap that had not been treated by PFA pellets at the taphole. We also wanted to test the effect of temperature-controlled sap storage for five intervals up to 7 days (167 h) prior to processing to syrup.
A cost analysis of processing maple sap to syrup for three fuel types, oil-, wood-, and LP gas-fired evaporators, indicates that: (1) fuel, capital, and labor are the major cost components of processing sap to syrup; (2) woodfired evaporators show a slight cost advantage over oil- and LP gas-fired evaporators; however, as the cost of wood approaches $50 per cord, wood as a fuel would no longer have this cost advantage; (3) economies of scale exist in processing maple sap to syrup; (4) in 1977 the total cost of production, including both sap production costs and processing costs, for a medium-size (750) gallons of syrup) operation was $8.36 per gallon of syrup for oil-fired evaporators, $7.97 per gallon of syrup for wood-fired evaporators, and $8.37 per gallon for LP gas-fired evaporators.
Maple syrup production starts by drilling a taphole in the tree. This process injures the wood, which may become discolored or decayed as a result. If trees are to be tapped, every effort must be made to minimize injury while obtaining the desired amount of sap. Information about tapholes is given here for the benefit of the producer. Some important points discussed are: how trees compartmentalize discolored and decayed wood associated with tapholes, how some tapping procedures lead to cambial dieback around the hole, the problem of overtapping related to increased use of mechanical tappers, and new information on the use of para formaldehyde pills, which can lead to more decay in trees.
The three grades of maple syrup and a commercial table syrup containing artificial flavor and 3 percent pure maple syrup were evaluated by 1,018 women in four cities. The results indicate that differences in preference for flavor are related to how close the respondents are to a maple syrup-production region. Differences in preference among grades of pure maple syrup were slight and in reverse order of the quality implied by the Federal grading standard. Outside of the region of maple syrup production, differences in preference between pure maple syrup and the commercial table syrup were marked, and favored the commercial syrup.