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Herbicide flashback is an undesirable response that results in damage or mortality of non-target plants near chemically treated plants. In severe instances, crop trees can be injured resulting in financial loss or inability to capture management objectives. Land managers need to know the potential limitations of using triclopyr acid (50% solution in water) and what quantity can cause damage to non-target trees (trees not aimed at for control via herbicide). Three naturally regenerated (previously clearcut) bottomland hardwood sites, ranging from 14–20 years of age, received partial overstory deadening using Trycera® herbicide. Residual "leave" trees experienced indirect herbicide uptake resulting in some trees either experiencing mortality or partial mortality with top dieback/epicormic branching. An increased probability of damage occurred as tree diameter decreased and the number of treated stems around the non-target stems increased. American sycamore, green ash, and sweetgum were most susceptible to flashback. This study examines the unanticipated chemical effect of deadening adjacent stems surrounding residual leave trees in poorly drained soils. [ABSTRACT FROM AUTHOR]

Because invasive tree species are being suppressed all over the world, there is a lack of basic information needed for their use in the processing industry. One piece of important information for woodworking applications is the air-dry density, which is 653 kg/m3 in the case of tree of heaven (Ailanthus altissima), 536 kg/m3 for box elder (Acer negundo), and 702 kg/m3 for green ash (Fraxinus pennsylvanica). The order of the 3 species is the same for oven-dry and basic density. In terms of compression and bending, tree of heaven has higher values than green ash. Because the strength of the tree of heaven and the green ash are largely the same as the common ash (Fraxinus excelsior), it can be replaced by these tree species. The properties of box elder wood are significantly different from those of

Because invasive tree species are being suppressed all over the world, there is a lack of basic information needed for their use in the processing industry. One piece of important information for woodworking applications is the air-dry density, which is 653 kg/m3 in the case of tree of heaven (Ailanthus altissima), 536 kg/m3 for box elder (Acer negundo), and 702 kg/m3 for green ash (Fraxinus pennsylvanica). The order of the 3 species is the same for oven-dry and basic density. In terms of compression and bending, tree of heaven has higher values than green ash. Because the strength of the tree of heaven and the green ash are largely the same as the common ash (Fraxinus excelsior), it can be replaced by these tree species. The properties of box elder wood are significantly different from those of sycamore (Acer pseudoplatanus), so this tree species is not suitable for replacement. [ABSTRACT FROM AUTHOR]

Emerald ash borer (EAB) (Agrilus planipennis), first identified near Detroit, Michigan, U.S., in 2002, has killed millions of ash trees (Fraxinus spp.) in 28 states and two Canadian provinces to date. Trunk injections of insecticide products containing emamectin benzoate (EB) (e.g., TREE-äge®) are often used to protect ash trees in landscapes from EAB, but wounds and potential injury resulting from injections are a concern. Researchers examined 507 injection sites on 61 trees and recorded evidence of secondary wounding (e.g., external bark cracks, internal xylem necrosis and pathogen infection). Researchers assessed 233 injection sites on 22 green ash and 24 white ash trees macro-injected with a low or a medium-high rate of EB in 2008 only, or in both 2008 and 2009. Only 12 of 233 injection sites (5%) were associated with external bark cracks and there was no evidence of pathogen infection. On 39 of the 46 trees (85%), new xylem was growing over injection sites. Researchers assessed 274 injection sites on 15 green ash trees injected annually with EB from 2008 to 2013 or injected in 2008 and again in 2011. Bark cracks were associated with four injection sites on three trees, but no evidence of injury was found on the other 12 trees. All 15 trees had new xylem laid over injection sites. Confocal laser scanning and polarizing digital microscopy were used to assess the integrity of discolored xylem tissue removed from the immediate area surrounding 140 injection sites on 61 trees. Researchers found no evidence of decay associated with discoloration. [ABSTRACT FROM AUTHOR]

We investigated growth, water relations, and water use of bare root (BR) and balled-burlapped (BB) Patmore green ash following transplanting into an irrigated landscape setting in a high desert climate. Treatments were green ash harvested as larger (40 mm caliper) BB and BR trees, and smaller BR stock (25 mm caliper). During establishment, we measured canopy growth for 3 years, and for 2 years plant water relations [predawn water potential and midday stomatal conductance (gS)] and water depletion within the root zone. All treatments expressed varying degrees of isohydric responses to root loss by reducing gS that maintained water potential nearly constant, but least so for the smaller BR trees. gS was greater than that of all larger trees, meaning that for the same cost in water potential as the larger trees, BR-Small benefitted from more open stomates and presumably greater carbon gain. Greater initial conductance apparently translated into more growth. Year 1, BR-Small trees had the least total leaf area, but by Year 3 total leaf area was not different among all treatments. Also during Year 1, the ratio of water use to local reference evapotranspiration [plant factor (PF)] was 0.36 for large BR trees vs. 0.56 for BB trees, similar to the recommended PF of 0.5 for trees in dry climates. These results suggest smaller BR trees are a cheaper alternative for high desert landscapes while reaching nearly equivalent growth to BB trees after 3 years. Achieving high growth of BR trees would need careful scheduling of irrigation amount and frequency based on leaf area, root zone size, and local reference evapotranspiration. [ABSTRACT FROM AUTHOR]

Background: To develop a set of transcriptome sequences to support research on environmental stress responses in green ash (Fraxinus pennsylvanica), we undertook deep RNA sequencing of green ash tissues under various stress treatments. The treatments, including emerald ash borer (EAB) feeding, heat, drought, cold and ozone, were selected to mimic the increasing threats of climate change and invasive pests faced by green ash across its native habitat. Results: We report the generation and assembly of RNA sequences from 55 green ash samples into 107,611 putative unique transcripts (PUTs). 52,899 open reading frames were identified. Functional annotation of the PUTs by comparison to the Uniprot protein database identified matches for 63 % of transcripts and for 98 % of transcripts with ORFs. Further functional annotation identified conserved protein domains and assigned gene ontology terms to the PUTs. Examination of transcript expression across different RNA libraries revealed that expression patterns clustered based on tissues regardless of stress treatment. The transcripts from stress treatments were further examined to identify differential expression. Tens to hundreds of differentially expressed PUTs were identified for each stress treatment. A set of 109 PUTs were found to be consistently up or down regulated across three or more different stress treatments, representing basal stress response candidate genes in green ash. In addition, 1956 simple sequence repeats were identified in the PUTs, of which we identified 465 high quality DNA markers and designed flanking PCR primers. Conclusions: North American native ash trees have suffered extensive mortality due to EAB infestation, creating a need to breed or select for resistant green ash genotypes. Stress from climate change is an additional concern for longevity of native ash populations. The use of genomics could accelerate management efforts. The green ash transcriptome we have developed provides important sequence information, genetic markers and stress-response candidate genes. [ABSTRACT FROM AUTHOR]

This study was carried out in Hungary, in an old unmanaged riparian poplar-willow forest during the breeding seasons of 2014 and 2015. The occurrence of two invasive tree species, the green ash and boxelder, is significant in the study area, which influences negatively the populations of native riparian tree species in Central Europe. We studied Great-spotted Woodpecker nest sites in the presence of these invasive species. Throughout the study period, eight and twelve nesting cavity trees were mapped. Trees were recorded in 20-20 circular plots of 0.05 ha both for each mapped nest trees and random plots as well. Species, diameter at breast height and condition were recorded for each tree. Composition and diversity of nest site and random plots were compared. Distributions and preferences were calculated for nest tree use. Most of the recorded trees were invasive. Nest site plots had more native trees compared to random plots. Nest site showed higher diversity in terms of all three variables. Decayed and dead willow and white poplar hybrid trees were preferred for nesting. Diameter at breast height of nest trees was between 30-90 cm. Studies about cavity excavators in transformed habitats have high importance for nature conservation of riparian forests. [ABSTRACT FROM AUTHOR]

Transcription factors play a key role to enable plants to cope with abiotic stresses. DREB2 regulates the expression of several stress-inducible genes and constitutes major hubs in the water stress signalling webs. We cloned and characterized a novel gene encoding the Fp DREB2A transcription factor from Fraxinus pennsylvanica, and a yeast activity assay confirmed its DRE binding and transcription activation. Overexpression of Fp DREB2A in R. pseudoacacia showed enhanced resistance to drought stress. The transgenic plant survival rate was significantly higher than that of WT in soil drying and re-watering treatments. Transgenic lines showed a dramatic change in root architecture, and horizontal and vertical roots were found in transgenic plants compared to WT. The vertical roots penetrated in the field soil to more than 60 cm deep, while horizontal roots expanded within the top 20-30 cm of the soil. A physiological test demonstrated that chlorophyll contents were more gradually reduced and that soluble sugars and proline levels elevated more sharply but malondialdehyde level stayed the same ( P < 0.05). Plant hormone levels of abscisic acid and IAA were higher than that of WT, while gibberellins and zeatin riboside were found to be lower. The root transcriptomes were sequenced and annotated into 2011 differential expression genes ( DEGs). The DEGs were categorized in 149 pathways and were found to be involved in plant hormone signalling, transcription factors, stimulus responses, phenylalanine, carbohydrate and other metabolic pathways. The modified pathways in plant hormone signalling are thought to be the main cause of greater horizontal and vertical root development, in particular. [ABSTRACT FROM AUTHOR]

In settled areas, electrical line safety is maintained by pruning encroaching trees. Identifying key predictors of branch elongation growth rate following pruning would assist in developing predictive models and optimizing pruning cycles. However, measuring branches in trees near electrical lines is complex and challenging. This paper describes an innovative approach using a handheld laser rangefinder to safely and accurately estimate growth from the ground. In-tree and ground-based laser measurements were highly correlated. This was followed by testing for correlations between branch growth response over a number of years after pruning and many biotic and abiotic factors for Fraxinus pennsylvanica, Acer platanoides, and Acer saccharinum, in the city of Montréal, Canada. In a sample of 59 trees, A. saccharinum had the greatest branch growth, followed by F. pennsylvanica, and finally A. platanoides. Branch growth increased following pruning and subsequently strongly declined, with A. platanoides declining the fastest. Branch inclination angle was positively correlated with growth rate for two species, but not for A. saccharinum. Among the types of pruning used, directional pruning techniques resulted in the least branch regrowth rate. Tree diameter was weakly related to branch growth rates. These results suggest that while growth conditions for street trees may be perceived as homogenous, there is substantial variation in branch growth response. This variation may be related to pruning history, or unmeasured abiotic or biotic variables. Estimating pruning cycle duration is a complex task and further work is needed to develop a predictive model for more accurate estimation of return times. [ABSTRACT FROM AUTHOR]

Invasive insects and pathogens have had major impacts on many forest tree species in North America that often affect forest structure and composition. Despite these effects, variation exists in the likelihood that some native species may persist following outbreaks and establishment of exotic insects and pathogens. Emerald ash borer ( EAB; Agrilus planipennis) has killed millions of trees near its introduction point in southeastern Michigan, and several recent studies in the area have predicted functional elimination of green ash ( Fraxinus pennsylvanica) from the landscape. Intensive management in yet unaffected stands that results from such predictions, however, demands data that examine the potential for persistence of the host species in the presence of the invasive. This study examined the potential for persistence of green ash in the presence of EAB by measuring surviving trees, regeneration, and seed rain characteristics in 17 small, near-pure stands of green ash in five consecutive growing seasons. Live trees experienced 58% mortality due to EAB, significantly less than that reported for ash in mixed stands. Approximately 20% of surviving trees exhibited signs of EAB, confirming that EAB mortality has slowed significantly but is ongoing. Sprouting was the dominant mode of ash regeneration in every year, and 27% of large sprouts produced seeds during a mast year in 2011. Advanced regeneration and new seedling establishment resulted in a sizable level of ash regeneration over the five years of the study even when sapling and seedling mortality was taken into account. Seed production was reduced considerably following EAB-caused mortality, but there was no evidence that seed dispersal limited seedling recruitment. These results suggest that the seed-producing ability of small trees and basal sprouts, as well as continued low-level mortality that will retain reduced host density, may allow green ash to persist in the presence of EAB. Although green ash populations and individual trees are unlikely to ever resemble the stature of those prior to EAB, their presence will continue to be an important component of forests on the landscape. [ABSTRACT FROM AUTHOR]

Emerald ash borer (EAB), Agrilus planipennis (Coleoptera: Buprestidae), is a devastating buprestid beetle introduced to North America from Asia. Asian ash trees exhibit resistance to EAB, likely due to a shared co-evolutionary history. Resistance to one pest, however, does not necessarily confer resistance to others. Should Asian ash be highly susceptible to North American herbivores, the utility of such species for hybridization, breeding programs, and establishment in managed landscapes could be compromised. Common urban problems, such as drought stress, can increase borer attack and survival and may further complicate the search for resistant plant material. The objectives of this study were to examine the relative susceptibility of green (Fraxinus pennsylvanica) and Manchurian (F. mandshurica) ash to EAB and indigenous borers and whether that susceptibility changed with drought stress. In a common garden experiment, EAB occurred more frequently and reached higher abundances in green than Manchurian ash. The frequency and abundance of bark beetles (Curculionidae), North American native clearwing borers (Sesiidae), and longhorn beetles (Cerambycidae) were similar in the two ash species. Generation time of EAB was uniformly one year and did not depend on ash species or water stress. Although borers increased as expected in stressed trees, the relative susceptibility of green and Manchurian ash to borers did not change. The findings suggest Manchurian ash may be resistant to several classes of borers, regardless of insect geographic origin, although these conclusions should be viewed with some caution until the results can be verified in larger trees. [ABSTRACT FROM AUTHOR]

Management strategies to control invasive species need information about dispersal distances to predict establishment potential. Fraxinus pennsylvanica is a North American anemochorous tree species that is invasive in many Central European floodplain forests. To predict seed-dispersal potential, the stochastic model WaldStat was used, which enables different options for directionality (isotropic and anisotropic) to be simulated. In this article, we (1) show empirical results of fructification and seed dispersal for this tree species. The model predicts approximately 250,000 seeds for one F. pennsylvanica tree. These results were used to (2) calculate species-specific dispersal distances and effects of wind direction. To consider the influence of wind on dispersal potential of the tree species, long-distance dispersal (LDD [95th percentile dispersal distance]) was calculated. Mean dispersal distances varied between 47 and 66 m. LDD values modelled along the main wind direction ranged from 60 to 150 m. Seed production, dispersal distance, and direction data were (3) incorporated into theoretical management scenarios for forest ecosystems. Finally (4), we discuss management options and the practical relevance of model scenarios in relation to the accuracy of spatial dispersal predictions. Further analyses should be focused on possible, well-adapted management concepts at stand level that could restrict the potential spread of invasive species. [ABSTRACT FROM AUTHOR]

Plants alter soil characteristics causing changes in their subsequent growth resulting in positive or negative feedback on both their own fitness and that of other plants. In a greenhouse study, we investigated whether the sign and strength of feedback changed across two distinct soil types, and whether effects were due to shifts in biotic or abiotic soil traits. Using soils from two different locations, we examined growth of the exotic invasive shrub, Lonicera maackii and the related native shrub, Diervilla lonicera, in unconditioned soils and in soils conditioned by previous growth of L. maackii, D. lonicera, and Fraxinus pennsylvanica. In a sandy acidic soil, L. maackii showed positive feedback in unsterilized soils, but its growth decreased and positive feedback became negative with sterilization in this soil. In a loamy circumneutral soil, L. maackii displayed neutral to negative feedback in unsterilized soils, but sterilization significantly increased growth in all conditioning treatments and caused feedback to become strongly negative. Native D. lonicera displayed negative feedback in unsterilized soil of both the sandy and loamy types, but sterilization either eliminated or reversed feedback relationships. Soil conditioning by L. maackii and F. pennsylvanica had very similar feedbacks on L. maackii and D. lonicera. While some abiotic soil traits varied across soil types and were affected by conditioning, soil biota sensitive to sterilization were apparently important mediators of both positive and negative feedback effects. [ABSTRACT FROM AUTHOR]

Comparative inventories in 1969 and 1970 and in 2008 of vegetation from 30 forest stands downstream of Garrison Dam on the Missouri River in central North Dakota showed (a) a sharp decline in cottonwood regeneration; (b) a strong compositional shift toward dominance by green ash; and (c) large increases in invasive understory species, such as smooth brome, reed canary grass, and Canada thistle. These changes, and others discovered during remeasurement, have been caused by a complex of factors, some related to damming (altered hydrologic and sediment regimes, delta formation, and associated wet-dry cycles) and some not (diseases and expansion of invasive plants). Dominance of green ash, however, may be short lived, given the likelihood that the emerald ash borer will arrive in the Dakotas in 5-10 years, with potentially devastating effects. The prospects for recovery of this valuable ecosystem, rich in ecosystem goods and services and in American history, are daunting. [ABSTRACT FROM AUTHOR]

The article discusses a study on the effects of planting depth on tree stability and growth for various species of trees including Whitesphire birch, green ash, snowdrift crabapple and bicolor oak. Of the four species, birch demonstrated the greatest instability when not planted deep enough. Perceived benefits of planting deep in containers to improve stability was observed only in birch and at the expense of significantly reduced root volume increase.

Multi-elemental profiles in bark of green ash trees collected in three representative areas of Buenos Aires, Argentina and Montevideo, Uruguay, were assessed as potential air pollution indicators. Ten elements: Al, Ba, Cr, Cu, Fe, Mg, Mn, Ni, Pb, and Zn, were measured using inductively coupled plasma optical emissions spectrometry from 70 samples collected in different environments: central, residential and rural (reference site), in order to compare spatial patterns of metal concentration. The samples used as a control were collected from a nature reserve situated far away from any significant influences, not even a nearby road. The reference site (RF) exhibited the lowest concentrations of Al, Cr, Fe, Ni, Pb, and Zn. However, Ba and Mn showed similar concentrations in all measured sites. Magnesium is the only element that had a greater concentration in RF than at the other sites. Copper did not show any clear pattern. The Centre of Montevideo (MVD) showed higher concentrations of Al, Ba, Cr, Fe, Pb and Zn than the Centre of Buenos Aires (BA). In the A sectors, Montevideo (SAMVD) showed higher concentrations of Al, Cu, Mg, Ni, and Zn and lower concentrations of Ba, Cr, Fe, Mn, and Pb than Buenos Aires (SABA). In the B sectors, Montevideo (SBMVD) showed higher concentrations of Al, Ba, Cu, Fe, Pb, and Zn and lower concentrations of Cr and Mg than Buenos Aires (SBBA), but similar concentrations of Mn and Ni. The use of bark for biomonitoring metals allowed us to detect concentration differences related to the urban fabric and the different kinds of vehicles and their fuels. In the cities, the differences in metal concentrations detected in bark were more striking between the sectors than between centers, despite CBA being much larger than CMVD in population, extension and vehicular traffic. [ABSTRACT FROM AUTHOR]

Abstract: Accounting for agroforestry contributions to carbon sequestration and cellulosic feedstock production requires biomass equations that accurately estimate biomass in open-grown trees. Since equations for open-grown trees are rare and developing these is expensive, existing forest-based equations are an attractive alternative for open-grown trees in carbon accounting and biomass modeling. How accurate this alternative is depends on how similar the key attributes, such as specific gravity, trunk shape, and crown architecture, are between open- and forest-grown trees. We evaluated the use of forest-derived specific gravity for conversion of volume to biomass for morphologically distinct open-grown species: green ash, ponderosa pine, and eastern redcedar. Trunk biomass was consistently and significantly underestimated from 6.3% to 16.6% depending on species, indicating open-grown trees have greater trunk specific gravity than forest-grown counterparts within the same geographic region; however a conclusive difference in branch specific gravity was not found between open- and forest-grown trees. Open-grown trees have greater trunk specific gravity, sharper trunk taper, and larger crown. When forest-based equations are used for trunk biomass of open-grown trees, the greater trunk specific gravity results in underestimation; however, the sharper trunk taper results in overestimation. Studies are needed to examine whether the underestimation could be offset by the overestimation and how the larger crown affects biomass estimation when forest-based equations are used for open-grown trees. Our results provide an essential understanding to interpret the biometric relationship of open- to forest-grown trees and to develop an efficient means how forest-based equations might be best modified for open-grown trees. [Copyright &y& Elsevier]

The article discusses the survey conducted to gather data on ash density in the states of Illinois, Indiana, Michigan, and Wisconsin and to project potential economic losses in the event of the establishment of emerald ash borer (EAB) in the communities. With the assumption of complete loss of ash attributed to EAB, landscape value losses for ash trees in the community boundaries was estimated to be between median-based 7.7 billion U.S. dollars and mean-based 15 billion U.S. dollars.

Abstract: Multielemental profiles in bark suber of green ash trees and road dust collected in three representative areas of Buenos Aires, Argentina were assessed as potential air pollution indicators. Ten elements: Al, Ba, Cr, Cu, Fe, Mg, Mn, Ni, Pb and Zn, were measured by inductively coupled plasma optical emissions spectrometry and their concentrations in the Buenos Aires road dust are reported for the first time. Measured concentrations and enrichment factors were used to characterize the environmental signatures of air pollution sources with impact in the studied areas. The analysis based on enrichment factors provided a common framework for the comparison of our results on tree bark and road dust with PM10 concentrations measured in previous studies. This unified analysis proved to be a valuable tool showing the consistency of our findings. The analysis based on either concentration profiles or enrichment factors showed that bark clearly differentiated sampling areas, resulting to be a better air pollution indicator than road dust. Road dust did not provide a clear differentiation between areas; this might be indicative of a certain degree of spatial mixture on street surfaces. [ABSTRACT FROM AUTHOR]

The article discusses a research study on how healthy and compromised green ash trees respond to wounds caused by standard trunk injection treatments. Two green ash trees were randomly selected from each of seven trunk-injection treatments that were chosen to represent a range of efficacy based on the active ingredient and the insecticide was injected in relationship to the borer infestation. It suggests that tree injections are tolerated in healthy green ash and have the potential as a tool to protect trees against exotic and destructive pests.

The article discusses research on green ash street trees whose trunks were injected with emamectin benzoate for emerald ash borer protection in Michigan in 2005 or 2006. The health of the trees was observed by yearly canopy thinning and dieback ratings for up to four years following a single treatment. For 2-3 years, a single trunk injection treatment of emamectin benzoate offered complete control of emerald ash borer larvae in 98 of 99 treated trees. Canopy ratings for treated trees remained the same for 2-4 years after trunk injection.

The article discusses the results of research on the effect of broadcast nitrogen fertilization rates and placement on the growth of green ash trees. The author reports that tree responses to slow-release nitrogen fertilization treatments were limited but the application of fertilizer to the inner half of the root zone helped improve caliper growth and relative chlorophyll content. The author concludes that the pre-existing level of fertility maybe a factor in the limited growth response.

Odonates are vulnerable during emergence, when they shed their larval skin (exuvia) to take flight as adults. Emergence-site selection should adapt to the local mortality risks. Here, l characterized emergence-site selection of Epitheca spinosa (Robust Baskettails) by noting the substrate, height, and distance from water of exuviae in a 300 m x 5 m plot at Weston Lake, Congaree National Park, Hopkins, SC. Of the 82 Robust Baskettail exuviae sampled, 52 (63.4%) were found on trees with corky bark (Nyssa aquatica [Water Tupelo], Nyssa biflora [Swamp Tupelo], Fraxinus pennsylvanica [Green Ash]), while no exuviae were found on the peeling, flaky trunks of Taxodium distichum (Bald Cypress) or the smooth, platy trunks of Acer rubrum (Red Maple). However, 26 (31.7%) exuviae were on T. distichum pneumatophores. This pattern was significantly different from the relative abundances of these substrate types (χ² = 19.8, df = 3, P < 0.001). Most exuviae (93.9%) were on substrates touching the water, suggesting that larvae climb directly from the water to their emergence site. The mean height of exuviae on trees was 3.3 ± 1.37 m, with a range from 1.8-7.7 m. High-climbing by Robust Baskettail larvae may be an adaptation to flooding at Weston Lake; major flood events (>3 m) are common (5 of the last 10 years) during their March-April emergence period. [ABSTRACT FROM AUTHOR]

Forty-five green ash (Fraxinus pennsylvanica) street trees in Toledo, Ohio were photographed, measured, and visually rated for conditions related to emerald ash borer (Agrilus planipennis)(EAB) attacks. These trees were later removed, and sections were examined from each tree to determine the length of time that growth rates had been impacted. A classification system was developed to discern the health of the trees along with a proposed method for early detection of a declining state of vigor. The classification is not an indicator of the degree of infestation, but rather tree health, which may be linked to the degree of EAB infestation. An evaluation of the tree sections places the EAB establishment no later than the 2004 growing season. A three-class system formulated from the evaluation of epicormic shoots, canopy light transmission, and EAB exit holes can be used to monitor the health of ash trees during EAB outbreaks. The classification system could potentially give homeowners, property managers, and agencies a way to detect and treat this problem earlier, especially in urban and park settings, and before trees are fully infested and exhibiting later-stage signs of decline. It is probably not practical for forest applications. Early detection and treatment not only can save selected trees, but it also might slow the spread of the insect, thereby giving additional trees a chance to survive the initial invasion. [ABSTRACT FROM AUTHOR]

1. Non-native plants can alter both native microbe communities and ecosystem processes. These changes may indirectly affect native plant communities. We tested whether an invasive plant influences other plant species through above- and below-ground microbial associations. These factors have received less attention than direct competition for resources in research on plant invasions. 2. Previous work in the mid-western US revealed that the above-ground fungal endophyte ( Neotyphodium coenophialum) in non-native tall fescue grass ( Lolium arundinaceum) reduced establishment of native tree species, slowing plant succession from grassland to forest relative to communities lacking the symbiont. Here, we examined potential soil-mediated mechanisms underlying these negative impacts on trees. 3. We challenged nine tree species with soil conditioned by tall fescue grass either with (E+) or without (E–) the symbiotic endophyte. We collected field soil from replicated, experimental E+ and E– field plots, sterilized half to eliminate soil microbes, then conditioned the soil in the greenhouse with either E+ or E– tall fescue. Individual tree seeds received one of five soil treatments: E– live, E– sterile, E+ live, E+ sterile, or no tall fescue conditioning (control). Tree survival and biomass were assessed after approximately 80 days. 4. Soil conditioning by E+ tall fescue reduced the biomass of three tree species ( Elaeagnus umbellata, Fraxinus pennsylvanica, Platanus occidentalis) and the survival of P. occidentalis relative to conditioning by E– tall fescue. However, decreased biomass occurred only in live soil, suggesting indirect effects of the endophyte via altered soil microbes. In addition, two species ( F. pennsylvanica, Prunus serotina) grew larger in both unconditioned soils and E– live soil relative to all other soil treatments, and two species ( Ailanthus altissima, P. occidentalis) performed poorly in all soil treatments relative to unconditioned soil. Finally, three species did not significantly respond to any soil treatment ( Acer negundo, Quercus palustris, Cercis canadensis). 5. Synthesis. Our results show that negative impacts of a non-native grass on native trees can depend on both above- and below-ground microbial associations. Because tree species responded divergently to soil conditioning, the endophyte symbiosis has the potential to alter plant succession and the future composition of forest communities. [ABSTRACT FROM AUTHOR]

The article offers information about a survey of the residents' perceptions towards their street trees on four streets in Toledo, Ohio, including Ash Trees, prior to their removal due to the attack of emerald ash borer. The survey suggests that the residents will be contented with a combination of tree species rather than planting a single tree species. On the other hand, the residents are worried due to the potential damages in sidewalks these trees can bring.

The article presents a study on emerald ash borer (Agrilus planipennis), which was identified in 2002 as the cause of widespread ash mortality in the U.S. and Canada. Emerald ash borers' density and canopy condition on green ash, white ash, and blue ash trees was monitored. It was found that the density increased by two to four times in white ash trees and green ash trees over a 3-year period. Focusing on the relatively preferred species is recommended to detect populations of A. planipennis.

The article presents a study to assess the risks of emerald ash borer to communities in North America by monitoring the street trees. It mentions that the stressors have the potential to alter the forest landscape. The South Dakota Division of Resource and Conversation and Forestry have categorized the communities based on the percentage of street tree population. Majority of the communities are in the low stability category due to the dominance of green ash in the street tree populations.

The article presents arboriculture and urban forestry research into temperature fluctuation in an eighteen-year-old Fraxinus pennsylvanica variant subintegerrima and its surrounding environment at the Lisle, Illinois-based Morton Arboretum. Temperature fluctuation measurements were made in the soil, sod, canopy, mulch, and soil surface with HOBO Pro temperature sensors.

The article investigates the potential economic impacts of emerald ash borer (Agrilus planipennis), a plant pest, on communities in Ohio. Assuming the complete loss of ash trees resulting from the emerald ash borer, losses in landscape value for these trees were estimated to be between $0.8 billion and $3.4 billion. Tree removal costs would range between $0.7 billion and $2.9 billion based on reported medians and means, respectively.

Most available information on the effects of planting depths for trees is anecdotal. Testing of interactions with other important cultural practices implemented during landscape establishment is lacking. Green ash (Fraxinus pennsylvanica H. Marshall), a hypoxia-tolerant species, and bougainvillea goldenraintree (Koelreuteria bipinnata A.R. Franchet), a hypoxia-intolerant species, were grown from seed in 2.3 L (#1) containers, which were later transplanted to 9.3 L (#3) black plastic containers and grown to a marketable size. Root collars of the plants were maintained level with the surface of the substrate. Green ash (1 May 2001) and bougainvillea goldenraintrees (27 April 2001) were transplanted to clay soil field plots with the root collars at 7.6 cm (3 in.) above soil grade, at grade, or 7.6 cm (3 in.) below grade. Planting depths for each species were in factorial combinations with 0, 7.6, 15.2, or 22.9 cm (0, 3, 6, or 9 in.), respectively, of pine bark mulch covering 0.74 m² (8 ft²) of soil beneath each tree. After 2 years, survival of bougainvillea goldenraintrees planted below grade was one-third that of those planted at or above grade. Survival and trunk diameter responses interacted with planting depth and mulch thickness for green ash. Planting below grade in combination with mulching reduced survival of green ash 25% to 50% after 3 years. Mulch applications reduced trunk diameters of green ash trees planted at or above grade. Mean soil water potentials were less negative with 7.6 cm (3 in.) of mulch (-5.8 kPa) compared to bare soil (-9.1 kPa), but increasing the mulch thickness to 22.9 cm (9 in.) inhibited penetration of irrigation water/rainfall (-16.2 kPa). These data suggest that planting with the root collar at or above grade enhances survival and growth potential of green ash and bougainvillea goldenraintree relative to planting below grade and that mulch applications should be only at thin layers sufficient to inhibit weeds. Bougainvillea goldenraintrees were more susceptible to the adverse effects of below-grade installation and excess mulch applications than were green ash trees. [ABSTRACT FROM AUTHOR]

Examines the effects of wildfire on recruitment of Fraxinus pennsylvanica in Eastern Montana woodlands. Significant negative effect of fire on Fraxinus pennsylvanica regeneration; Reasons for recommending controlled burning for regenerating trees; Description of the trees.

Growth parameters and carbohydrate contents were determined for Fraxinus pennsylvanica Marsh. seedlings inoculated with Glomus macrocarpum Tul. and Tul. or Glomus fasciculatum (Thaxt.) Gerd. and Trappe, and for uninoculated controls that were grown in a greenhouse for 16 weeks at root temperatures of 15, 25 or 35 °C. Seedling growth responded rapidly to mycorrhizal inoculation when root temperatures were 25 or 35 °C. Response to inoculation at 15 °C was delayed but seedlings at this temperature finally attained the size of those grown at 25 and 35 °C. Growth of noninoculated plants was best at 15 and 25 °C. Inoculation with mycorrhizal fungi moderated the adverse effect of higher root temperature. Infection of roots by both fungal species was greater at 25 °C than at 15 or 35 °C. Sugar content increased as root temperature increased whereas starch content was inversely related. Both soluble sugar and starch content were less in mycorrhizal than in nonmycorrhizal seedlings. [ABSTRACT FROM AUTHOR]

Green ash (Fraxinus pennsylvanica Marsh.) was either inoculated or not with Glomus etunicatum Becker and Gerd. and grown for 37 d to permit root colonization. Root hydraulic conductivity (Lp) per unit length was measured on excised root systems to examine the influence of vesicular-arbuscular (VA) mycorrhiza inoculation, seedling size, phosphorus (P) nutrition, and biomass distribution. Fertilization with P eliminated significant differences in seedling size and dry matter distribution between mycorrhizal (M) and non-mycorrhizal (NM) seedlings, but VA mycorrhizas increased root and leaf P concentration. Root Lp was similar in M and NM seedlings of similar size, and was lower in M seedlings for a given root P concentration. Root Lp decreased with age and weight, and increased as the proportion of dry weight in the leaves increased in both M and NM seedlings. Mycorrhizal colonization had no significant effect on root Lp in the absence of a significant growth response. [ABSTRACT FROM AUTHOR]

Inoculation of seedlings of green ash (Fraxinus pennsylvanica Marsh.) with vesicular-arbuscular (VA) mycorrhizal fungi, significantly increased seedling heights, root collar diameters, dry matter accumulations and phosphorus (P) nutrition relative to control seedlings. The ability of these VA mycorrhizal fungis, which were isolated form low P forest soils (5-7 mg kg-1), to enhance seedling growth in a high-P (148 mg kg-1) nursery soil provides evidence for the occurrence of VA mycorrhizal fungi which may be effective under both high and low soil P conditions. There was a significant positive correlation between foliar P concentration and percentage infection. Despite significant differences in tissue P concentrations among seedlings receiving different inoculum treatments, the degree of growth enhancement was the same. Growth increase due to enhanced P nutrition in seedlings with higher concentration of foliar P may have been offset by an increased drain on host photosynthate via production and maintenance of greater amounts of fungal biomass, or may have been limited by the low K fertility of the nursery soil. Colonization percentages in roots of seedlings of green ash were high despite high soil P concentrations. The pattern of infection development was unique for each VA mycorrhizal fungal species. A modification of the gridline intercept technique was used to assess intensity of infection. Infection for all endophytes during the period of most rapid vegetative host growth was predominantly arbuscular. However, arbuscular intensity fluctuated during this period. Vesicles increased in number with time but always made up a small percentage of total infection. [ABSTRACT FROM AUTHOR]

The effects of Glomus macrocarpum and a high rate of nutrient addition upon growth, root carbohydrate and P content, and mycorrhizal development in green ash (Fraxinus pennsylvanica) seedlings were studied over two growing seasons. Mycorrhizal and similarly growing non-mycorrhizal seedlings had similar seasonal patterns in growth and in root carbohydrate and P content. No clear difference in mycorrhizal development as as result of nutrient treatment occurred until the middle of the second growing season when the percent root infection of seedlings that received low nutrient increased and that of seedlings that received high nutrient decreased. A seasonal cycle with two phases in the interaction of the VA mycorrhiza and host growth, root: shoot ratios, root infection, root content of soluble sugars, starch and P, arbuscule and vesicle numbers, and spore population is proposed. [ABSTRACT FROM AUTHOR]

The relationship between seed weight, embryo weight, ash content and maximum size attained by seedlings dependent on their own food reserves was investigated in 24 species of Compositae. The fraction of total seed weight contributed by the seed coat increased with seed weight from 15% in Erigeron canadensis to 61% in Tragopogon pratensis. Seedling weight was proportional to embryo weight raised to the power of ⅔. That is, the larger the embryo the less carbon it assimilated per unit weight of embryo. The relative growth rate of the seedlings during the first 3 weeks was inversely proportional to ln embryo weight. The root weight ratios of the seedlings were inversely proportional to ln embryo weight. The ash content of the seeds was negatively correlated with their weight but absolute mineral content per seed was directly proportional to maximum seedling size attained, regardless of seed size. It is postulated that the relatively larger seed coats of big seeds are a defence against increased risk of predation. The ash contents and root weight ratios of the seedlings suggest that the growth of small seedlings is limited by soil nutrients and that of large seedlings by light. [ABSTRACT FROM AUTHOR]

The relationship between the growth of the host, and development and morphology of a vesicular-arbuscular mycorrhizal fungus was studied in green ash (Fraxinus pennsylvanica Marsh.). A yearly cycle with three phases is suggested. Phase I is a period of fast shoot growth, slow root growth, rapid colonization of the root system by the mycorrhizal fungus and greater numbers of fungal arbuscles than vesicles. Phase II is a period of fast root growth and a decline in the percentage of root length infected. Phase III is. characterized by senescing leaves, infection percentages increasing to a static level, and greater numbers of vesicles than arbuscles. Mycorrhizal green ash seedlings generally had greater heights, weights and root collar diameters and lower root: shoot ratios than non-mycorrhizal seedlings. [ABSTRACT FROM AUTHOR]

Radioautographs by light and electron microscopy of callus cells of green ash (Fraxinus pennsylvanica Marsh.) that had been fed low levels of the growth factor [SUP3]H myo-inositol indicated an almost exclusive incorporation of the label into the cytoplasmic constituents. These results contrast with those from most other studies of incorporation in higher plants. The incorporation here of myo-inositol suggests that its prime function is the synthesis of cytoplasmic membrane systems of the cell rather than in the polysaccharide component of the primary wall. [ABSTRACT FROM AUTHOR]

Effects of short-term (32 days) flooding on photosynthesis, stomatal conductance, relative growth rate and tissue starch concentrations of flood-intolerant Quercus alba L. (white oak), bottomland Quercus nigra L. (water oak), bottomland Fraxinus pennsylvanica Marshall. (green ash) and flood-tolerant Nyssa aquatica L. (water tupelo) seedlings were studied under controlled conditions. Net photosynthetic rates of flooded N. aquatica seedlings were reduced by 25% throughout the 32-day flooding period. Net photosynthetic rates of flooded Q. alba seedlings fell rapidly to 25% of those of the control seedlings by Day 4 of the flooding treatment and to 5% by Day 16. In F. pennsylvanica and Q. nigra, net photosynthetic rates were reduced to 50% of control values by Day 8 but remained at approximately 30 and 23%, respectively, of control values by Day 32. Leaves of flooded Q. alba seedlings accumulated approximately twice as much starch as leaves of non-flooded control plants, whereas root starch concentrations decreased to 67% of those of control plants by the end of the 32-day flooding treatment. In contrast, flooding caused only a small increase in leaf starch concentrations of N. aquatica plants, but it increased root starch concentrations to 119% of those of the control plants by the end of the experiment. The co-occurring bottomland species, Fraxinus pennsylvanica and Q. nigra, differed from each other in their patterns of stomatal conductance and root starch concentrations. We conclude that the maintenance of low leaf starch concentrations, and high pre-flood root tissue starch concentrations are important characteristics allowing flood-tolerant species to survive in flooded soils. [ABSTRACT FROM PUBLISHER]

In Fraxinus pennsylvanica seedlings which were injured by epidermal scraping, wound periderm was initiated before callus formation. Wound periderm was formed before normal periderm and stimulated formation of normal periderm in uninjured tissue near the wound. [ABSTRACT FROM AUTHOR]

Seedlings of Fraxinus pennsylvanica, Robinia pseudoacacia, and Ailanthus altissima were grown from seed for 30 days in different daylengths and used to investigate early periderm and xylem formation. Periderm and secondary xylem did not develop in dark-grown seedlings. Xylem increments of Fraxinus pennsylvanica and Robinia pseudoacacia seedlings increased significantly with each increase in daylength from 8 to 24 hours. Xylem increment in seedlings of Ailanthus altissima showed a slight but non-significant response to daylength. Phellogen formation and activity were stimulated in all three species as daylength was increased. Periderm was not present in 30-day-old Ailanthus altissima seedlings grown on 8-hour days, but phellem increased significantly as daylength was increased from 16 to 24 hours. In Fraxinus pennsylvanica seedlings periderm was formed earlier and phellem increment was greater in seedlings grown on 24-hour daylengths than in those grown on 16-hour daylengths. In the latter regime phellogen was formed sooner and was more active than in seedlings grown on 8-hour daylengths. Periderm increment in Robinia pseudoacacia seedlings could not be measured because of crushing of phellem, but it formed sooner and appeared to proliferate faster in seedlings grown on or 24 hour days than on shorter daylengths. Differences in time to formation of the vascular cambium and phellogen and in production of xylem and phellem indicated differences in physiological controls. [ABSTRACT FROM AUTHOR]

Seedlings of Fraxinus pennsylvanica were grown from seed and subjected to various treatments which removed leaves, cotyledons, stem apices or buds at periods up to 35 days after cotyledon emergence. In addition, portions of the stems of several seedlings were kept in darkness during the experiments. Periderm did not form in seedlings from which all foliage was removed as it emerged. Seedlings with any foliage developed periderm, but periderm-stimulatory substances were not released from foliage until it reached a certain stage of development. Both cotyledons and leaves exported periderm-stimulatory substances, but leaves appeared to export more. Substances produced in the apical meristem or actively growing buds had no effect on phellogen formation and activity, but appeared to regulate the kind of periderm cells produced, their differentiation, and their anticlinal divisions. The stimuli for periderm formation and subsequent development were strongly basipetal and only weakly acropetal. However, darkening the stem below the foliage appeared to moderate the polar transport of periderm-stimulatory substances. Foliar products increased wound-periderm formation and were essential for wound-stimulated formation of normal periderm. [ABSTRACT FROM AUTHOR]