Sugar Maple Wood Research Articles

CHARACTERIZATION OF LIGNIN DISSOLVED DURING ALKALINE SODIUM BOROHYDRIDE AND HYDROGEN PEROXIDE PRETREATMENTS OF SUGAR MAPLE (ACER SACCHARUM)

Sugar maple (Acer saccharum) wood chips were pretreated with aqueous sodium hydroxide, sodium borohydride, and hydrogen peroxide pretreatments, and the characterization (i.e., amount, molar masses, and molar mass distributions) of the lignin dissolved during the pretreatments was performed. Of the applied pretreatments, especially borohydride pretreatments were efficient in dissolving lignin from this feedstock, as 20% to 28% of the dissolved organics were found to consist of dissolved lignin, contributing to 3.4% to 9.0% of the initial wood lignin. Corresponding values for 2.5% and 5.0% alkaline peroxide pretreatments were from 5.9% to 9.2% dissolved lignin of the total dissolved organics and from 1.1% to 3.2% of the initial wood lignin. Additionally, determined molar masses and molar mass distributions indicated that borohydride pretreatments generally led to the formation of smaller-molar-mass lignin fragments when compared to reference pretreatments and to pretreatments conducted with alkaline peroxide process, indicating more efficient lignin degradation caused by borohydride addition. For example, Mn and Mw values of the analyzed reference effluents were 54%-62% and 66%-71% higher when compared to the corresponding borohydride effluents, respectively.

Effects of helix angle and feed per knife on the surface quality of sugar maple and black spruce boards produced by planing

ABSTRACT A conventional straight knife cutterhead and three helical knife cutterheads were tested for planing sugar maple (Acer saccharum Marsh.) and black spruce (Picea mariana (Mill.) B.S.P.) woods. The effects of helix angle and feed per knife (FK) on roughness, tactical perception, and anatomical features of the planed surfaces were evaluated. Rk and Rpk parameters were found to be more descriptive in evaluating the roughness of these woods and proved to be good indicators of tactile perception. Roughness increased as the helix angle and feed per knife increased for both wood species. Sugar maple showed smoother surface than black spruce. Surfaces planed with helical knives showed a fuzzy texture resulting from cell-wall fibrillation. For sugar maple wood, the differences in roughness between straight and 40° helical knives were small. Therefore, the latter must be preferred for planing this species. Roughness of planed black spruce also increased as helix angle increased and in this case its effect depended on FK. The straight knife produced the lowest roughness, for all studied FKs. Planing with helical knives produced higher roughness as a result of cell-wall fibrillation. This defect was more pronounced than that of sugar maple, and by far more present with helical knives of 50° and 60°. Therefore, straight knives working at low FK (1.3 mm) should be preferred for planing black spruce wood when roughness is a critical concern. Possible benefits provided by rougher surfaces planed by helical knives are discussed.

Effects of helix angle and feed per knife on cutting forces, noise, and power consumption produced during helical planing of sugar maple wood

A conventional straight knife cutterhead and three helical knife cutterheads were tested for planing sugar maple wood (Acer saccharum Marsh.). Effects of helix angle and feed per knife (FK) on maximum cutting forces, sound level, and power consumption were evaluated. A 3-axis dynamometer, an array microphone, and a watt transducer were used to simultaneously record the forces, sound level, and power consumption during machining, respectively. Parallel (FP), positive and negative normal (FNP and FNN), lateral (FL), resultant (FR) forces, and sound level increased as FK increased. Helical tools produced lower FP, FNP, FNN, and FR. Parallel forces tended to decrease as helical angle increased. Differences among helical tools were not significant for normal forces. Helical tools produced higher FL at medium (2.9 mm) and high (4.7 mm) feeds per knife. FR decreased as helix angle increased. The impacts of these cutting forces on the appearance of surface defects and ways to reduce them were discussed. Helical cutterheads considerably generated lower sound pressure level, with a maximum difference of up to 8 dB(A). At low FK (1.3 mm), helical tools required slightly lower cutting power.

Surface creation and cutting characteristics during sugar maple wood scratching with spherical cone grit

A series of single-grit cutting tests were performed with spherical cone tools on sugar maple (Acer saccharum) wood to investigate its surface creation and cutting behavior. The tools with apex angles 2 $$\alpha$$ = 84 $$^\circ$$ and 2 $$\alpha$$ = 108 $$^\circ$$ were selected to clarify the effect of negative rake angles. It was found that there was no discernable pile-up on both sides of the scratches. Grit with 2 $$\alpha$$ = 108 $$^\circ$$ made less fractured fibers protrude from the top surface. The affluent porosity of wood was emphasized, and an analytical model of elastic deformation for single-grit cutting has been established. There seems to be a transitional depth of grit penetration, after which the elastic recovery keeps a constant value. The average cutting force ratio of grit with 2 $$\alpha$$ = 84 $$^\circ$$ was visibly higher, referring to better cutting performance. The size effect of grit with 2 $$\alpha$$ = 84 $$^\circ$$ was more pronounced in the two cutting directions. Compared with research on metal materials, the evident energy absorption capacity of sugar maple accounts for the relatively high overall specific energy.

Decay of birdseye sugar maple (Acer Saccharum) and curly red maple (Acer Rubrum)

Two figured woods, commonly known as birdseye maple ( Acer saccharum , sugar maple) and curly maple ( Acer rubrum , red maple), were exposed to brown rot and white rot fungi in a standard laboratory decay test and compared with unfigured wood of each species, respectively. For the birdseye maple, two levels of figure intensity were used: wood with heavy figure and wood with light figure. Heavily figured birdseye maple wood was decayed significantly less by the brown rot fungus Rhodonia placenta than unfigured maple wood or lightly figured maple wood. However, heavily figured birdseye maple wood was decayed significantly more by two white rot fungi, Trametes versicolor and Irpex lacteus , than unfigured maple wood but was not decayed significantly more than lightly figured wood. For both brown rot and white rot fungi, lightly figured birdseye maple wood did not decay significantly differently compared with unfigured wood. Likewise, there was no significant difference in decay between curly red maple wood and unfigured red maple wood for either brown rot or white rot fungi. Results suggest chemical or anatomical differences in the heavily figured birdseye sugar maple wood affect decay by brown rot and white rot fungi. These findings may be useful to hobbyists and woodworkers needing to protect wood or who partially decay wood to produce spalted wood for decorative purposes.

Incorporation of ligno-cellulose nanofibrils and bark extractives in water-based coatings for improved wood protection

CNFs (cellulose nanofibrils) and BEs (bark extractives) are low-cost, sustainable, and biodegradable materials, which had potential to be used in numerous applications, including biomass composites, food packaging, and polymer materials. In this study, CNFs with high lignin content (LCNFs) and BEs were prepared from western red cedar and lodgepole pine bark, respectively. These were then homogeneously dispersed in water-based acrylic coatings to paint on the surfaces of spruce and sugar maple wood samples. The results showed that the distribution of LCNFs and BEs in the coatings was homogeneous and uniform. The LCNFs had a significant effect on improving the hardness (2–3 levels higher than neat coating) and abrasive resistance (40% higher wear-out rotations), and a content of 2% was sufficient to realize these optimum coating properties. Moreover, the incorporation of LCNFs and BEs increased the aging resistance of the water-based acrylic paints due to an effective inhibitory effect on crack formation and extension conferred by the LCNFs and the free radical scavenger activity provided by the BEs during the aging process. The optimum content of 2% for LCNFs (2% in primer and 2% in top coating) and BEs (in top coating) substantially increased the effectiveness of water-based acrylic coatings in regard to wood protection.

Surface Chemical Changes of Sugar Maple Wood Induced by Thermo-Hygromechanical (THM) Treatment

The aim of this study was to investigate the effects of heat and steam on the chemical properties of thermo-hygromechanical (THM)-densified sugar maple wood. The THM densification process was performed at two different temperatures (180 °C and 200 °C) with and without steam. The functional groups, surface chemical composition and internal structure and components of the control and densified samples were investigated using attenuated total reflection Fourier transform infrared (ATR-FTIR), X-ray photoelectron (XPS) spectroscopy and pyrolysis gas chromatography-mass spectrometry (Py-GC/MS). The obtained results suggest that the THM densification treatment resulted in significant chemical changes on the wood surface. The results of the ATR-FTIR spectra confirmed the decomposition of hemicelluloses and the relative increase of cellulose and lignin contents on the wood surface. The Py-GC/MS and XPS results show an increase of the oxygen/carbon atomic (O/C) ratio, which indicated that chemical substances containing oxygenated functionality were formed through the densification process. The densification treatment favored the depolymerization of hemicelluloses and cellulose as indicated by an increased anhydrous sugar (levoglucosan) release during the pyrolysis process. Densification also facilitated the cleavage of the lignin side chains, resulting in increased phenyl units with short chains released during the pyrolysis process.

Heat and Mass Transfer Properties of Sugar Maple Wood Treated by the Thermo-Hygro-Mechanical Densification Process

This study investigated the evolution of the density, gas permeability, and thermal conductivity of sugar maple wood during the thermo-hygro-mechanical densification process. The results suggested that the oven-dry average density of densified samples was significantly higher than that of the control samples. However, the oven-dry density did not show a linear increase with the decrease of wood samples thickness. The radial intrinsic gas permeability of the control samples was 5 to 40 times higher than that of densified samples, which indicated that the void volume of wood was reduced notably after the densification process. The thermal conductivity increased by 0.5–1.5 percent for an increase of one percent moisture content for densified samples. The thermal conductivity of densified wood was lower than that of the control samples. The densification time had significant effects on the oven-dry density and gas permeability. Both densification time and moisture content had significant effects on thermal conductivity but their interaction effect was not significant.

Effects of heat and steam on the mechanical properties and dimensional stability of thermo-hygromechanically-densified sugar maple wood

Effects of heat and steam were investigated relative to the mechanical properties and dimensional stability of thermo-hygromechanically-densified sugar maple wood (Acer saccharum Marsh.). The densification process was performed at four temperatures (180 °C, 190 °C, 200 °C, and 210 °C) with and without steam. The hardness, bending strength, bending stiffness, and compression set recovery of the control and densified samples were determined. The effects of heat and steam on the density profile of the samples across thickness were also investigated. The results suggested that the effects of steam on the mechanical properties and dimensional stability of sugar maple wood were more important than that of heat’s influence. Compared to the samples densified without steam, the samples densified with steam showed higher values for hardness, bending strength, bending stiffness, compression set, and density, but much lower compression set recovery when treatment temperature was below 200 °C. High temperature combined with steam contributed to decreased compression set recovery. The lowest compression set recovery was obtained after the first swelling/drying cycle for all of the treatments. A higher weight loss occurred at 210 °C, which resulted in a noticeable decrease of wood density.

Deposition of fluorocarbon groups on wood surfaces using the jet of an atmospheric-pressure dielectric barrier discharge

This work reports the functionalization of sugar maple (Acer saccharum) wood surfaces following their exposure to the jet of an atmospheric-pressure dielectric barrier discharge operated in either Ar or N2 with C3F8 (octafluoropropane) as the growth precursor for plasma-enhanced chemical vapour deposition. Analysis of the current–voltage characteristics (I–V) revealed a filamentary behaviour in all conditions. While more intense current peaks were observed after addition of C3F8 in Ar, a decrease in the discharge current was seen in N2/C3F8 plasmas. Optical emission spectroscopy showed the apparition of a CF2 + continuum and CF2 rovibrational bands between 225 and 350 nm with increasing applied voltage and precursor concentration in the Ar plasmas; a feature ascribed to the presence of plasma-generated C3F8 fragments. In such conditions, water contact angle (WCA) measurements indicated that freshly sanded wood samples became highly hydrophobic, with WCAs in the 140° range and excellent dimensional stability for a period of up to 125 days. X-ray photoelectron spectroscopy revealed that such behaviours result from the deposition of highly hydrophobic CF x groups on the surface. On the other hand, no increase in surface hydrophobicity was observed following exposure to the jet of N2/C3F8 plasmas, probably due to their much lower precursor fragmentation levels.

An Investigation into Capacitive Performances and Impedance Contributions Due to Structural Differences of Biochar Thin Film and Monolith Supercapacitor Electrodes

Supercapacitors are an upcoming, high power density energy storage technology. Unlike in batteries, energy is stored physically through the adsorption of oppositely charged ions to a surface. Electrode materials that facilitate this process have high conductivity, extensive porosity, and high specific surface area. Porous carbon powders are used commercially, being pressed into thin films and held together with a binder material [1]. While carbon nanotubes and graphene are the focus of many researchers in this field, our group is investigating a unique alternative: biochar. Biochar is pyrolyzed biomass, and our group uses different types of wood as precursor materials. Through a controlled pyrolysis process, it is possible to preserve the internal macrostructures of wood, creating pathways throughout the carbon structure that should facilitate ion transport. By creating large, continuous monolithic pieces of carbon, devices can be constructed differently from the status quo. Using monolithic slices as electrodes simplifies the manufacturing process, reduces the number of ancillary components required per device, eliminates the need for a non-conductive binder material, and enables the construction of larger electrodes. Currently there is a lack of understanding regarding the relationships between biochar macrostructures and capacitive performance. While monolithic biochar electrodes were found to show similar capacitive performance to their thin film counterparts in [2], the study did not include an evaluation from a structural point of view. Additionally, although it was found that increasing electrode thickness of thin films resulted in an increase in device resistance [3], this relationship has not been explored for monolithic electrodes nor at a relevant scale, as it becomes possible to make electrodes hundreds of times thicker than those currently used [1]. Competitive capacitive performance of powdered biochar thin film electrodes compared to thin film alternatives has been demonstrated in [4] and [5]. The overall goal of this project is to determine if monolithic biochar electrodes can compete with the capacitive performance of powdered biochar thin film electrodes. By constructing monolithic slices and powdered thin films from the same biochar, electrochemical influences of the macrostructure are investigated. Capacitive performance metrics such as charge/discharge rate capability and self-discharge rates are explored for the two electrode structures, as well as for different electrode thicknesses. Frequency-dependent resistances and their respective contributions to total device resistance are analyzed through Electrical Impedance Spectroscopy (EIS). Mass transfer and diffusional resistances, which are believed to be highly dependent on both electrode geometry and structure will be reported. Characterization of the electrode materials using N2 and CO2 physisorption; helium pycnometry; and SEM imaging coincides with the electrochemical testing methods to help resolve the causes of performance differences and evaluate their significance. Preliminary results show that monolithic biochar electrodes up to 1mm thick have comparable specific capacitance performance to the thin films at 100mA/g, which was the highest current density employed thus far. Upcoming work will apply larger current densities to determine if the channels of the macrostructures contribute to high power performance or reduce volumetric capacitance. Monolithic electrodes up to 5mm thick are able to achieve similar specific capacitances to the thin films at a low current density (5mA/g), but their performance degrades significantly with charge rate. The experiments mentioned in the preceding paragraphs were all conducted on biochar from sugar maple wood. Research direction for early 2017 will involve analysis on biochar from different types of precursor wood. Soft and hard woods, and the variety of species within these categories have vastly different types and sizes of internal structures (Figure) [6]. The effects of these macrostructures on capacitive performance and ion transport will be assessed, and these results will be available for presentation.

Study of Organosolv Lignins as Adhesives in Wood Panel Production.

Organosolv lignins obtained from sugar maple bark and wood were studied as adhesives for wood particleboard production. Organosolv pulping of sugar maple wood and bark was carried out in the presence of Lewis acid FeCl3 as a catalyst. The organosolv lignins recovered from this process were investigated by determination of Klason plus acid-soluble lignin content, of sugars by HPLC analysis, and of ash content. Structural characterizations of these lignins were performed by Fourier-transform infrared (FT-IR) and by 31P NMR. The results of the latter studies indicate that the content of free phenolic groups was more important in bark than in wood lignin. The gel permeation chromatography (GPC) analyses results suggested that the weight-average molecular mass of wood lignin was higher than that of bark lignin. The studied organosolv lignins were used for the preparation of particleboards as recovered and in combination with glyoxal or isocyanate. It was found that sugar maple bark lignin, as such or modified with isocyanate, was a more efficient adhesive than its wood counterpart. On the contrary, it was the organosolv wood lignin combined with glyoxal which was a more efficient adhesive than its bark counterpart. In combination with isocyanate, it was the sugar maple bark organosolv lignin which was determined to have the best adhesive performance of all studied lignins.

Optimization of the Thermo-Hygromechanical (THM) Process for Sugar Maple Wood Densification

Densified wood is a promising engineered wood product, especially for heavy-duty applications. This study optimized the temperature and duration of the thermo-hygromechanical (THM) densification process applied to sugar maple (Acer saccharum Marsh.) wood. The response variables studied were compression set recovery and hardness. The THM densification process was performed at three temperatures (180°C, 200 °C, and 220 °C), densification times (450 s, 900 s, and 1350 s), and post-treatment times (900 s, 1350 s, and 1800 s). Response surface methodology was used to analyze the impact of the three parameters. The effect of temperature on the density profile across thickness was also determined. The results suggested that the optimum densification conditions resulting in high hardness and low compression set recovery were obtained at a temperature of 180 °C, a densification time of 1004 s, and a post-treatment time of 1445 s. Additionally, the density of the densified samples was relatively homogeneous across thickness, although it was dramatically increased compared with control samples. However, density did not increase linearly with temperature. A much higher weight loss occurred at 220 °C, resulting in a significant decrease in density and hardness, whereas little compression set recovery was observed for sugar maple densified at this temperature.

Biochar amendment altered the molecular-level composition of native soil organic matter in a temperate forest soil

Environmental contextBiochar amendment in soil can sequester carbon but may also stimulate microbial activity, potentially enhancing soil organic matter degradation. We incubated biochar in a temperate forest soil and characterised the soil organic matter composition using molecular-level biomarker and nuclear magnetic resonance techniques. Biochar amendment altered the native soil organic matter composition and decreased the concentration of easily degradable soil organic matter components. AbstractBiochar amendment in soil can sequester carbon and improve soil water and nutrient retention, fertility and plant productivity. However, biochar may stimulate microbial activity, leading to priming or accelerated soil organic matter (OM) degradation, which could alter the native soil OM molecular composition. To investigate this, we amended sugar maple wood biochar (pyrolysed at 500°C) at four concentrations (0, 5, 10 and 20 metric tons per hectare) in a temperate forest soil for 32 weeks. Solvent extraction and CuO oxidation were used to characterise free compounds and lignin-derived phenols respectively at 8 week intervals, while base hydrolysis was used to examine plant wax, cutin and suberin components at the end of the incubation. Stimulated soil microbial activity following an adaptation period (16 weeks) resulted in increased inputs of microbial- and plant-derived soil OM components including solvent-extractable short-chain n-alkanols and n-alkanoic acids, long-chain n-alkanes and n-alkanols, and sugars. Degradation parameters for base-hydrolysable cutin- and suberin-derived compounds did not show any significant degradation of these plant biopolymers. Analysis of lignin-derived phenols revealed lower concentrations of extractable phenols and progressive oxidation of syringyl and vanillyl phenols at higher biochar application rates over time. Solution-state 1H nuclear magnetic resonance analysis of base-extractable soil OM after 32 weeks showed a decrease in the proportion of labile OM components such as carbohydrates and peptides and a relative increase in more recalcitrant polymethylene OM constituents in the amended soils. The biochar-mediated shifts in soil OM composition and reduction in labile carbon may reduce soil fertility in biochar-amended systems with long-term amendment.

Kinetic Modeling of Ethanol Batch Fermentation by Escherichia Coli FBWHR Using Hot-Water Sugar Maple Wood Extract Hydrolyzate as Substrate

A recombinant strain of Escherichia coli FBWHR was used for ethanol fermentation from hot-water sugar maple wood extract hydrolyzate in batch experiments. Kinetic studies of cell growth, sugar utilization and ethanol production were investigated at different initial total sugar concentrations of wood extract hydrolyzate. The highest ethanol concentration of 24.05 g/L was obtained using an initial total sugar concentration of 70.30 g/L. Unstructured models were developed to describe cell growth, sugar utilization and ethanol production and validated by comparing the predictions of model and experimental data. The results from this study could be expected to provide insights into the process performance, optimize the process and aid in the design of processes for large-scale production of ethanol fermentation from woody biomass.

Shifts in microbial community and water-extractable organic matter composition with biochar amendment in a temperate forest soil

Biochar amendment in soil has been proposed as a carbon sequestration strategy which may also enhance soil physical and chemical properties such as nutrient and water holding capacity as well as soil fertility and plant productivity. However, biochar may also stimulate microbial activity which may lead to increased soil CO2 respiration and accelerated soil organic matter (OM) degradation which could partially negate these intended benefits. To investigate short-term soil microbial responses to biochar addition, we conducted a 24 week laboratory incubation study. Biochar produced from the pyrolysis of sugar maple wood at 500 °C was amended at concentrations of 5, 10 and 20 t/ha in a phosphorus-limited forest soil which is under investigation as a site for biochar amendment. The cumulative soil CO2 respired was higher for biochar-amended samples relative to controls. At 10 and 20 t/ha biochar application rates, the concentration of phospholipid fatty acids (PLFAs) specific to Gram-positive and Gram-negative bacteria as well as actinomycetes were lower than controls for the first 16 weeks, then increased between weeks 16–24, suggesting a gradual microbial adaptation to altered soil conditions. Increases in the ratio of bacteria/fungi and lower ratios of Gram-negative/Gram-positive bacteria suggest a microbial community shift in favour of Gram-positive bacteria. In addition, decreasing ratios of cy17:0/16:1ω7 PLFAs, a proxy used to examine bacterial substrate limitation, suggest that bacteria adapted to the new conditions in biochar-amended soil over time. Concentrations of water-extractable organic matter (WEOM) increased in all samples after 24 weeks and were higher than controls for two of the biochar application rates. Solution-state 1H NMR analysis of WEOM revealed an increase in microbial-derived short-chain carboxylic acids, lower concentrations of labile carbohydrate and peptide components of soil OM and potential accumulation of more recalcitrant polymethylene carbon during the incubation. Our results collectively suggest that biochar amendment increases the activity of specific microorganisms in soil, leading to increased CO2 fluxes and degradation of labile soil OM constituents.

3D numerical analysis of the thermal effect and dielectric anisotropy on thawing frozen wood using microwave energy

This paper addresses the thawing of frozen wood by microwave. The effect of thermal and dielectric anisotropy on thawing wood is considered. The nonlinear heat conduction problem involving phase changes such as wood freezing is solved using three-dimensional volumetric specific enthalpy based on finite-element analysis. The dielectric and thermophysical properties are a function of temperature, moisture content and structural orientation. The specific volumetric enthalpy approach is validated by analytical, numerical and experimental testing. Finally, we studied the thermal effect and dielectric anisotropy on thawing frozen sugar maple wood (Acer saccharum) at 2466 MHz.

Determining the Linear Viscoelastic Region of Sugar Maple Wood by Dynamic Mechanical Analysis

Dynamic mechanical analysis (DMA) is a powerful analytical technique to study wood structure and properties. In order to draw firm conclusions from results obtained by DMA, strain rate of tests conducted by DMA should be within the linear viscoelastic region (LVR) of the tested material. In this study, the LVR limit of sugar maple (Acer saccharum Marsh.) wood specimens was determined in the three directions under a range of temperature and relative humidity (RH) conditions. The results demonstrated that wood had very different LVR limits in the different directions. The longitudinal direction had much lower LVR limits than the radial and tangential directions. While LVR limits were not strongly affected by changes in temperature and RH in the longitudinal direction, they proved very sensitive to these factors in the tangential direction. The results of this study showed the importance of determining LVR limits before running any test by DMA.

Modification of cellulose nanocrystals as reinforcement derivatives for wood coatings

Abstract Cellulose nanocrystal (CNC), an emerging renewable nanomaterial, was subjected to carbon chains grafting in order to improve its dispersion and its ability to transfer its rigidity properties into less polar matrixes, especially acrylic wood coatings. Chemical modifications used to this purpose are required to be simple, not affecting the CNC main structure and compatible or synergistic to oligomer reticulation inside the targeted UV-waterborne formulation. Those modifications were carried out using either alkyl quaternary ammonium bromides or acryloyl chloride. These new chemical functionalities, not inducing deep structural changes in modified CNCs, were highlighted through nuclear magnetic resonance, infrared and nitrogen content analyses. CNC derivatives were better dispersed in aqueous acrylic coating as suggested by atomic force microscopy, with a mean surface roughness falling from 9 to 6 nm on the coatings containing unmodified and treated CNCs, respectively. For mechanical evaluations, the coatings including various CNC derivatives were applied on sugar maple wood, a much appreciated material as indoor timber or wooden furniture which requires an efficient surface protection. The abrasion tests indicated that the modified CNCs confer a higher scratch resistance, with an improvement from 24% to 38% for coatings containing CNC derivatives over those with unmodified CNC.

The Relationship of the Sapstreak Fungus, <i>Ceratocystis virescens</i>, to Sugar Maple Dieback and Decay in Northern Michigan

Unusually high levels of dieback have recently been reported in sugar maple, Acer saccharum Marsh., in Upper Michigan, and a network of plots was established to determine the extent and factors associated with the dieback. A possible contributor to this dieback is sapstreak disease caused by Ceratocystis virescens (Davidson) Moreau. Unhealthy trees with considerable crown dieback were evaluated across the western Upper Peninsula, MI to determine the prevalence of the sapstreak fungus using a minimally destructive sampling technique. Approximately 8% of 90 trees sampled were sapstreak positive and approximately 10% of trees were positive at one site that had recently been harvested. While the high levels of maple dieback present in these forests appear not to be directly caused by widespread sapstreak disease, the occurrence of sapstreak may be significantly impacting trees at some locations. However, even when present on a low number of trees, the biointeraction of sapstreak and decay rates from other fungi could be important for future tree mortality and value to the forest industry. Therefore, the effect of two sapstreak fungal isolates on the amount of decay caused by two common maple white rot fungi, Trametes versicolor (L.:Fr.) Pilat. And Irpex lacteus (Fr.:Fr.) Fr. was tested in the laboratory. Sugar maple wood blocks were precolonized by two native isolates of C. virescens followed by inoculation and incubation with decay fungi. Mean percent weight loss of blocks by white rot decay fungi ranged from 39% to 55%, but decay rates were not significantly affected by the presence of the sapstreak fungus.