Quercus Research Articles

Analysis of Aroma Components of Enzymatic Hydrolysis Products of Oak Lignin from Different Producing Areas

The morphology and structure of lignin in French oak, American oak and Chinese Mongolian oak were observed and compared by scanning electron microscopy (SEM). The results showed that the surface of lignin after enzymatic hydrolysis was more irregular and the contact area was obviously increased. GC-MS detected 3 kinds of lignin, 4 kinds of components and 30 kinds of volatile substances. The lignin content of French oak was the highest (8911.5 ± 512.2 μg/L, 29 kinds), followed by that of American oak (8071.7 ±541.9 μg/L, 26 kinds), and that of Mongolian oak was the least (7903.3 ± 492.5 μg/L, 26 kinds). The results of aroma characteristics analysis, principal component analysis and heat map analysis showed that the aroma components of the three kinds of oak lignin were significantly different. French oak lignin could provide more volatile phenols, with obvious smoky, woody and sweet flavor. Mongolian oak lignin carries more phenolic and ester compounds, providing a relatively soft floral, fruity flavor. American oak lignin has a relatively average aroma substance content, which can bring strong and complex complex aroma characteristics.

Effects of four bolete species on ectomycorrhizae formation and development in Pinus thunbergii and Quercus acutissima

BackgroundBolete cultivation is economically and ecologically valuable. Ectomycorrhizae are advantageous for plant development and productivity. This study investigated how boletes affect the formation of Pinus thunbergii and Quercus acutissima ectomycorrhizae using greenhouse-based mycorrhizal experiments, inoculating P. thunbergii and Q. acutissima with four species of boletes (Suillus bovinus, Suillus luteus, Suillus grevillei, and Retiboletus sinensis).ResultsThree months after inoculation, morphological and molecular analyses identified S. bovinus, S. luteus, S. grevillei and R. sinensis ectomycorrhizae formation on the roots of both tree species. The mycorrhizal infection rate ranged from 40 to 55%. The host plant species determined the mycorrhiza morphology, which was independent of the bolete species. Differences in plant growth, photosynthesis, and endogenous hormone secretion primarily correlated with the host plant species. Infection with all four bolete species significantly promoted the host plants’ growth and photosynthesis rates; indole-3-acetic acid, zeatin, and gibberellic acid secretion increased, and the abscisic acid level significantly decreased. Indole-3-acetic acid was also detected in the fermentation broths of all bolete species.ConclusionsInoculation with bolete and subsequent mycorrhizae formation significantly altered the morphology and hormone content in the host seedlings, indicating growth promotion. These findings have practical implications for culturing pine and oak tree species.

Modelling of sap flux density of oak in a humid region in China

AbstractTranspiration plays a vital role in determining the watershed water cycle. However, we still have little knowledge of the characteristics of tree transpiration in the Hanjiang River Basin, which is the water source for the middle route of South‐to‐North water diversion project. Here, we measured sap flux density of oak trees (Quercus, the dominant species here) at the 10‐min resolution for 2 years and explored its response to the environmental conditions. The incoming short‐wave radiation and vapour pressure deficit well explained the variation of daytime sap flux density, and a statistical model was then proposed to calculate the daytime sap flux density correspondingly; then a nighttime sap flux density module was proposed based on the daytime sap flux density calculation. Sap flux density showed clear counter‐clockwise hysteresis response to incoming short‐wave radiation, and clockwise hysteresis response to vapour pressure deficit. Our sap flux density model can well reproduce the corresponding hysteresis response to incoming short‐wave radiation and vapour pressure deficit. This study unravelled the environmental controls of sap flux density of the oak trees in the Hanjiang River Basin, proposed an efficient model for the sap flux density simulation, provided important knowledge for understanding the corresponding forests' water use, which is of critical significance in determining the water availability for the middle route of the South‐to‐North water diversion project.

Post-fire regeneration of oak-pine forest across a chronosequence in western Mexico: key species for forest restoration

Background: High-severity fires are serious anthropogenic threats to forests, as they can cause forest degradation on unrecoverable scales. Therefore, understanding the patterns and drivers of post-fire regeneration is essential to designing restoration proposals.
 Hypotheses: After a high-severity fire, we expected greater species richness and abundance of individuals in flat sites than in hillside sites since seeds, nutrients, and organic matter accumulate in flat landforms. Compared to some Pinus species, Quercus species are more drought-tolerant after a forest fire and, therefore, they are expected to dominate post-fire chronosequences.
 Study site: The study was conducted in the “La Primavera” Flora and Fauna Protection Area.
 Methods: We sampled vegetation and microenvironmental variables from 2021 to 2022 at 18 sites located on flat and hillside areas, at 3, 9, and ≥ 20 years since the last high-severity forest fires (TSF).
 Results: The richness of woody and herbaceous species was higher at 3 TSF and 9 TSF. The topographic condition did not significantly drive the richness and abundance of woody species, but richness and abundance of herbaceous species were significantly greater in flat sites. The oak tree Quercus resinosa Liebm. was the dominant species throughout the chronosequence.
 Conclusions: Quercus resinosa represents a foundational species for recovering forest structure and composition. Flat sites may act as regeneration nuclei, but hillside sites require greater restoration efforts.

Cryopreservation of sessile oak (Quercus petraea (Matt.) Liebl.) plumules using aluminium cryo-plates: influence of cryoprotection and drying

Background Quercusseeds that are recalcitrant to desiccation and freezing temperatures cannot be stored in gene banks under conventional conditions. However, the germplasm of some recalcitrant seeded species can be stored in liquid nitrogen (–196 °C). Unfortunately, for many species, among them for almost the whole genus Quercus, an effective cryostorage method is still unknown. In this study, we propose a successful cryostorage protocol for Quercus petraea (Matt.) Liebl. germplasm using plumules (a shoot apical meristem of an embryo) frozen on aluminium cryo-plates.ResultsThe plumules isolated from the acorns of ten provenances were prestored in 0.5 M sucrose solution (for 18 h). To form alginate beads (one plumule per bead), the plumules were placed in the wells of a cryo-plate and embedded in calcium alginate gel. For cryoprotection, the encapsulated plumules were immersed in cryoprotectant solution containing 2.0 M glycerol and different concentrations of sucrose (0.8–1.2 M) for 40 min at 25 °C and desiccated under a laminar flow cabinet for 1.0–4.0 h. Cryo-plates with plumules were directly immersed in liquid nitrogen and then cryostored for 30 min. For rewarming, cryo-plates with plumules were immersed in 1.0 M sucrose solution and rehydrated for 15 min at 25 °C. Survival rates varied from 25.8 to 83.4 were achieved after cryoprotection in 1.0 M sucrose solution and the drying of plumules for 2 h. The in vitro regrowth rate of cryopreserved plumules varied among provenances and was 26–77%.ConclusionsThis study presents, for the first time, a successful, simple and effective protocol for the cryopreservation of Q. petraea germplasm that could be used in gene banks. The experiment was successfully repeated on seeds from various provenances, each yielding similar, good results. However, seed quality and storage time after harvesting are important factors in plumule regrowth after cryopreservation.

Detecting Pathogenic Phytophthora Species Using Volatile Organic Compounds.

There are several highly damaging Phytophthora species pathogenic to forest trees, many of which have been spread beyond their native range by the international trade of live plants and infested materials. Such introductions can be reduced through the development of better tools capable of the early, rapid, and high-throughput detection of contaminated plants. This study utilized a volatilomics approach (solid-phase microextraction coupled to gas chromatography-mass spectrometry) to differentiate between several Phytophthora species in culture and discriminate between healthy and Phytophthora-inoculated European beech and pedunculate oak trees. We tentatively identified 14 compounds that could differentiate eight Phytophthora species from each other in vitro. All of the Phytophthora species examined, except Phytophthora cambivora, uniquely produced at least one compound not observed in the other species; however, most detected compounds were shared between multiple species. Phytophthora polonica had the most unique compounds and was the least similar of all the species examined. The inoculated seedlings had qualitatively different volatile profiles and could be distinguished from the healthy controls by the presence of isokaurene, anisole, and a mix of three unknown compounds. This study supports the notion that volatiles are suitable for screening plant material, detecting tree pathogens, and differentiating between healthy and diseased material.

Urbanization exacerbates climate sensitivity of eastern United States broadleaf trees.

Tree growth is a key mechanism driving carbon sequestration in forest ecosystems. Environmental conditions are important regulators of tree growth that can vary considerably between nearby urban and rural forests. For example, trees growing in cities often experience hotter and drier conditions than their rural counterparts while also being exposed to higher levels of light, pollution, and nutrient inputs. However, the extent to which these intrinsic differences in the growing conditions of trees in urban versus rural forests influence tree growth response to climate is not well known. In this study, we tested for differences in the climate sensitivity of tree growth between urban and rural forests along a latitudinal transect in the eastern United States that included Boston, Massachusetts, New York City, New York, and Baltimore, Maryland. Using dendrochronology analyses of tree cores from 55 white oak trees (Quercus alba), 55 red maple trees (Acer rubrum), and 41 red oak trees (Quercus rubra) we investigated the impacts of heat stress and water stress on the radial growth of individual trees. Across our three-city study, we found that tree growth was more closely correlated with climate stress in the cooler climate cities of Boston and New York than in Baltimore. Furthermore, heat stress was a significant hindrance to tree growth in higher latitudes while the impacts of water stress appeared to be more evenly distributed across latitudes. We also found that the growth of oak trees, but not red maple trees, in the urban sites of Boston and New York City was more adversely impacted by heat stress than their rural counterparts, but we did not see these urban-rural differences in Maryland. Trees provide a wide range of important ecosystem services and increasing tree canopy cover was typically an important component of urban sustainability strategies. In light of our findings that urbanization can influence how tree growth responds to a warming climate, we suggest that municipalities consider these interactions when developing their tree-planting palettes and when estimating the capacity of urban forests to contribute to broader sustainability goals in the future.

The genus Quercus: metabolites, biological activity and mechanisms of action

The genus Quercus: metabolites, biological activity and mechanisms of action

Anatomical Characteristics and Assessment of Wood Fiber Quality of Mature Pedunculate Oak (Quercus robur L.) Trees Grown in Different Environmental Conditions

From productive and ecological point of view, Quercus robur L. is an extremely important species and the investigation of its anatomical properties is very significant in terms of its technical and technological utilization. The paper deals with the analysis of the wood fiber characteristics (fiber length, fiber lumen width, double-cell wall thickness, Runkel ratio) of mature pedunculate oak trees in the non-flooded (Management Unit "Vinična-Žeravinac-Puk") and flooded area (Management Unit "GVO 83 b"). One of the aims of the study is to determine the wood fiber quality and the possibility of use in paper and pulp production. When the mean values of the analysed anatomical characteristics are compared, the results show slightly higher values in the non-flooded area, except for the Runkel ratio. The radial pattern of the investigated characteristics depending on the age shows growth in the non-flooded area, while the same tendency in the flooded area was found for the fiber length only. It was recorded that fiber lumen width, double-cell wall thickness and Runkel ratio decreased in the final annual rings. The wood fiber quality for use in pulp and paper production is the greatest in the juvenile zone, unlike sapwood zone, regardless of the site conditions.

Sole Survivors: Using Tree-Trunk Wells from Archaeological Excavations to Inform Reconstructions of Medieval Deforestation, and Future Reforestation

Abstract This paper represents an attempt at a detailed analysis of woodland presence and dynamics during the Middle Ages (AD 500-1500), as a contribution to the current debate on large-scale reforestation in the Netherlands. Palynological data for this particular period are scarce and allow only global reconstructions. To widen our search for historical woodland proxies, we investigated the potential of archaeologically excavated tree-trunk wells. We carried out a nation-wide inventory of this type of well, in which the shaft is formed by hollowed-out tree trunks, typically large oak trees. Our suspicion that such trees indicate the local presence of (old) woodland in the past was confirmed by a marked positive correlation with spatial reconstructions based on other sources of information: archaeological (charcoal kilns) and non-archaeological (place names and historical references). The observed correlations suggest that mapping the distribution of precisely dated tree-trunk wells can indeed contribute to achieving fairly detailed reconstructions of medieval woodland cover.

A dendrochronological examination of a recent decline of chestnut oak across southern Indiana

Oak (Quercus) species are a major component of much of the eastern forest. Unfortunately, multiple species have experienced well-documented episodes of decline and mortality over the past century. A mortality event in chestnut oak (Q. prinus) across southern Indiana in 2016 sparked concern about the health of chestnut oak, leading to an effort to identify factors that triggered and contributed to the event. We evaluated stand conditions, tested for the presence of Phytophthora cinnamomi, and collected tree cores from chestnut oak trees within diseased stands and nearby healthy stands. We found no evidence that P. cinnamomi was associated with mortality. Instead, our dendrochronological analysis suggests that a series of dry June conditions followed by wet March conditions weakened vulnerable trees, allowing the exceptional drought in 2012 to incite decline. Greater basal area increment prior to growth decline, along with a higher probability of decline on mesic north-northeastern slopes, suggest that vulnerable individuals may have been those that preferentially allocated carbon into above ground growth at the expense of developing drought resilient root systems.

Differences between provenances and pedunculate oak (Quercus robur) trees after the lethal dose (LD50) of electrolyte leakage

The study conducted on pedunculate oak cultures of different provenances from the ,,Plaiul Fagului” Scientific Reserve evaluated the level of electrolyte leakage from leaves after the application of a lethal heat shock (DL50). The results indicate a significant physiological variation in the response of trees to heat stress. Analysis of variance revealed significant differences between pedunculate oak provenances, indicating a greater resistance to heat shock in the descendants of trees from more distant origins (Edineț and Baimaclia) compared to those from the central area (Plaiul Fagului and Hâncești), where the common arboretum is installed. It can be assumed that there is a significant variation in the physiological response of trees from different provenances to thermal stress, and descendants from more distant areas have exhibited a more pronounced adaptive response than those from areas closer to the common arboretum, which have similar environmental conditions to the cultivation area. The preliminary results of the study suggest that the selection of the best trees and provenances for afforestation can be made based on the resistance of oak trees to heat stress. In addition, the adaptation of trees to specific environmental conditions can be improved through the selection of these provenances, especially for future afforestation in the context of climate change.

Chromosome-scale genomes of Quercus sichourensis and Quercus rex provide insights into the evolution and adaptation of Fagaceae

The Fagaceae, a plant family with a wide distribution and diverse adaptability, has garnered significant interest as a subject of study in plant speciation and adaptation. Meanwhile, certain Fagaceae species are regarded as highly valuable wood resources due to the exceptional quality of their wood. In this study, we present two high-quality, chromosome-scale genome sequences for Quercus sichourensis (848.75 Mb) and Quercus rex (883.46 Mb). Comparative genomics analysis reveals that the difference in the number of plant disease resistance genes and the nonsynonymous and synonymous substitution ratio (Ka/Ks) of protein-coding genes among Fagaceae species are related to different environmental adaptations. Interestingly, most genes related to starch synthesis in the investigated Quercoideae species are located on a single chromosome, as compared to the outgroup species, Fagus sylvatica. Furthermore, resequencing and population analysis of Q. sichourensis and Q. rex reveal that Q. sichourensis has lower genetic diversity and higher deleterious mutations compared to Q. rex. The high-quality, chromosome-level genomes and the population genomic analysis of the critically endangered Q. sichourensis and Q. rex will provide an invaluable resource as well as insights for future study in these two species, even the genus Quercus, to facilitate their conservation.

Spicing up oak forest restoration: a preliminary report of the protective use of chili peppers in direct seeding of acorns

Direct sowing of acorns is a technique for oak forest restoration, however, high seed predation by mammals can occur and cost‐effective alternatives to protect acorns are therefore required. The present study evaluated the protection provided by chili peppers (Capsicum annuum and Capsicum pubescens) to acorns of Quercus germana, an endangered endemic oak tree of the cloud forests. Greenhouse and field experiments were established to evaluate the effect of chili peppers on acorn removal, germination, and seedling emergence. These processes were related to the prevalent microhabitat characteristics where the acorns were introduced, and the fauna that consumed chili peppers and acorns was identified using camera traps. In the greenhouse trial, more seedlings emerged from acorns covered by fruits of C. pubescens (65.71 ± 8.14) and C. annuum (57.14 ± 8.49%) compared to unprotected acorns (31.43 ± 7.96%). Contrary to expectation, acorn removal in the field was greater using C. pubescens than the unprotected acorns, particularly in microsites with lower tree cover and higher grass dominance. Acorn removal was similar among chili pepper treatments. These results are explained by the camera trap records, which showed bird species consuming Capsicum fruits, thus exposing the acorns to subsequent removal and/or consumption by rodents. The studied Capsicum fruits had no negative effect on acorn germination and seedling emergence under greenhouse conditions, and future practices could, therefore, involve the use of different techniques to prevent the discovery of chili peppers by birds; for example, using green chili peppers for camouflage, or hiding them under litter or herbaceous vegetation.

Phylogenetic relationships of Quercus species (Fagaceae) in Vietnam based on multiplexed inter simple sequence repeat genotyping by sequencing

Quercus is the largest genus of the family Fagaceae in the world and the second-largest in Vietnam, with approximately 50 species. However, the phylogeny study of the Quercus genus in Vietnam has yet to be thoroughly explored. In this study, we utilize the genome-wide single-nucleotide polymorphisms (SNPs) data obtained through Multiplexed Inter Simple Sequence Repeat Genotyping by sequencing (MIG-seq) to explore the phylogenetic relationships among Quercus species in Vietnam. The results of this study reveal that all Quercus species in Vietnam belong to subgenus Cerris and the phylogenetic analysis strongly supports the recognition of two infrageneric sections: Quercus and Ilex section for the Vietnamese Quercus. These results also confirm that the monophyly of Quercus in Vietnam is strongly supported by both morphological and molecular data. The results of this study also align entirely with previous research, indicating that Quercus species in Asia fall under the subgenus Cerris, comprising two sections: section Ilex and section Cyclobalanopsis.

Habitat Degradation Facilitates the Invasion of Neophytes: A Resurvey Study Based on Permanent Vegetation Plots in Oak Forests in Slovenia (Europe).

The spread of neophytes (non-native plant species) challenges the conservation status and ecological integrity of forests, especially in lowland areas. Long-term resurvey studies are needed to evaluate the temporal dynamics of neophytes in forests; however, such data are scarce. In 2023, we resampled a set of 45 permanent vegetation plots (established in 1992/93) in two forest vegetation types: oak-hornbeam forests dominated by Quercus robur and colline oak-beech forests dominated by Q. petraea. Over the last 30 years, oak forests have experienced extensive oak tree mortality, with the degree of habitat degradation being greater in Q. robur forests. In the early 1990s, only three neophytes with low abundance were recorded across all plots. In the 2023 resurvey, the total number of neophytes increased to 22 species (15 herbaceous and 7 woody species), comprising 6.9% of the total species pool in the understory layer. The increase in the plot-level number and cover of neophytes was significant in plots dominated by Q. robur but not in those with Q. petraea. The most frequent neophytes were Impatiens parviflora (present in 31% of plots), Solidago gigantea (27%), Erigeron annuus (16%) and Erechtites hieraciifolia (16%). The richness and cover of neophytes were significantly affected by the tree layer cover (negative correlation) and the degree of soil disturbance (positive correlation). All neophytes established in disturbed patches, whereas the occurrence of I. parviflora was exceptional as it was able to colonize less degraded, shaded understory environments. Habitat degradation (the mortality-induced loss of stand-forming oak trees resulting in extensive tree layer cover decrease) emerged as a key driver promoting neophyte proliferation, coupled with the impact of management-induced disturbances affecting overstory and soil conditions. The spread is expected to continue or even intensify in the future because novel light regimes and disturbances make forest habitats less resistant to neophyte proliferation.

Revealing legacy effects of extreme droughts on tree growth of oaks across the Northern Hemisphere

Forests are undergoing increasing risks of drought-induced tree mortality. Species replacement patterns following mortality may have a significant impact on the global carbon cycle. Among major hardwoods, deciduous oaks (Quercus spp.) are increasingly reported as replacing dying conifers across the Northern Hemisphere. Yet, our knowledge on the growth responses of these oaks to drought is incomplete, especially regarding post-drought legacy effects. The objectives of this study were to determine the occurrence, duration, and magnitude of legacy effects of extreme droughts and how that vary across species, sites, and drought characteristics. The legacy effects were quantified by the deviation of observed from expected radial growth indices in the period 1940–2016. We used stand-level chronologies from 458 sites and 21 oak species primarily from Europe, north-eastern America, and eastern Asia. We found that legacy effects of droughts could last from 1 to 5 years after the drought and were more prolonged in dry sites. Negative legacy effects (i.e., lower growth than expected) were more prevalent after repetitive droughts in dry sites. The effect of repetitive drought was stronger in Mediterranean oaks especially in Quercus faginea. Species-specific analyses revealed that Q. petraea and Q. macrocarpa from dry sites were more negatively affected by the droughts while growth of several oak species from mesic sites increased during post-drought years. Sites showing positive correlations to winter temperature showed little to no growth depression after drought, whereas sites with a positive correlation to previous summer water balance showed decreased growth. This may indicate that although winter warming favors tree growth during droughts, previous-year summer precipitation may predispose oak trees to current-year extreme droughts. Our results revealed a massive role of repetitive droughts in determining legacy effects and highlighted how growth sensitivity to climate, drought seasonality and species-specific traits drive the legacy effects in deciduous oak species.

Acorns as a Source of Valuable Compounds for Food and Medical Applications: A Review of Quercus Species Diversity and Laboratory Studies

Acorns, the fruit of oak trees of the genus Quercus, have been known to people for generations worldwide. In ancient times, they were an important part of culinary traditions and folk medicine. Their exploitation for food over the years has been significantly diminished, which may arise from the high content of tannins responsible for a bitter taste and anti-nutritional properties. However, more and more studies show acorns’ potential nutritional and health benefits. Furthermore, new reports are emphasizing the health-promoting properties of tannin-decomposition products. This review aims to present the available studies on the phytoconstituents variation in the acorns of different Quercus species and their possible significance for food and medical applications. In this study, the results of lab-scale food processing, as well as in vivo and in vitro experiments, are included. The literature data proved that acorn products (flour, oil, and extracts) are intensively examined due to their dietary, antioxidant, anti-microbial, anti-inflammatory, anti-cancer, and neuroprotective activities provided by their bioactive compounds. The general conclusion is that this raw material can be used more widely in the future as an ingredient in functional foods, supplements, and drugs.

Outdoor aeroallergen impacts on asthma exacerbation among sensitized and nonsensitized Philadelphia children

Outdoor aeroallergens, such as pollens and molds, are known triggers of asthma exacerbation; however, few studies have examined children's aeroallergen response based on sensitization. Our aim was to compare the relative impact of aeroallergen levels on asthma exacerbation between pediatric patients with asthma who tested positive or negative for sensitization to particular allergens. A case-crossover design study was conducted to examine associations between outdoor aeroallergen levels and asthma exacerbation events among children living in Philadelphia, Pennsylvania, who were treated within a large pediatric care network. Sensitization to common allergens was characterized in a subset of patients with asthma exacerbation who had undergone skin prick testing (5.5%). Odds ratios (ORs) and 95% CIs were estimated in all patients with asthma exacerbation and in those sensitized or not sensitized to aeroallergens. Children who were sensitized to a particular allergen had higher odds of asthma exacerbation with exposure to the allergen (ie, early-season tree pollen, oak tree pollen, early-season weed pollen, and late-season molds) than did all patients with asthma or nonsensitized patients. For example, the association between early-season tree pollen and asthma exacerbation among sensitized children (>90th percentile vs ≤25th, OR= 2.28 [95% CI= 1.23-4.22]) was considerably stronger than that estimated among all patients (OR= 1.34 [95% CI= 1.19-1.50]), and it was also substantially different from the lack of association seen among nonsensitized children (OR= 0.89 [95% CI= 0.51-1.55] [P value for heterogeneity= .03]). More prevalent allergy testing may be useful for prevention of asthma exacerbation by informing interventions targeted to sensitized children and tailored for particular aeroallergens.

Evaluation of the Root Rupture Method for Controlling Belowground Spread of the Oak Wilt Pathogen (Bretziella fagacearum) in Northeast Wisconsin, USA

Abstract Oak wilt, caused by the pathogen Bretziella fagacearum, is a destructive disease on oak (Quercus) species in the United States. Established methods to control the belowground spread of oak wilt are not appropriate in all circumstances; thus, forest health managers have a strong need for alternative methods for disease control. We evaluated the effectiveness of operational stump excavation treatments (i.e., “root rupture” method) applied between 2004 and 2014 to control belowground spread of oak wilt on two forests in northeast Wisconsin, USA. The root rupture method achieved a high level of disease control (≥85% of evaluated disease infection centers) for 5 years by harvesting red oak trees within infection centers and uprooting the stumps and associated root mass. The likelihood of disease control success depended on the initial size of the infection center that was treated, with larger infection centers being less likely to be contained with a single treatment than small infection centers. This study highlights the importance of early detection and prompt management in oak wilt suppression programs. Study Implications: Forest management agencies and organizations in the North Central United States continue to face oak wilt epidemics. No single tool or treatment method ensures complete containment of oak wilt; thus, most managers carefully consider all the tools and techniques available to them and determine what best suits their budget and land use priorities. Stump excavation (i.e., “root rupture” method) is a cost-effective treatment for halting belowground spread of the oak wilt fungus, Bretziella fagacearum, that can achieve a high level of disease control. In northern red oak (Quercus rubra) stands with high economic value, this treatment can be applied as a group selection, with the value of the timber potentially offsetting the cost of treatment. The opportunity for complete disease control decreases as oak wilt infection centers increase in size; thus, monitoring and early control actions are critical.