Cercis Canadensis Research Articles

Habitat fragmentation influences genetic diversity and differentiation: Fine-scale population structure of Cercis canadensis (eastern redbud).

Forest fragmentation may negatively affect plants through reduced genetic diversity and increased population structure due to habitat isolation, decreased population size, and disturbance of pollen‐seed dispersal mechanisms. However, in the case of tree species, effective pollen‐seed dispersal, mating system, and ecological dynamics may help the species overcome the negative effect of forest fragmentation. A fine‐scale population genetics study can shed light on the postfragmentation genetic diversity and structure of a species. Here, we present the genetic diversity and population structure of Cercis canadensis L. (eastern redbud) wild populations on a fine scale within fragmented areas centered around the borders of Georgia–Tennessee, USA. We hypothesized high genetic diversity among the collections of C. canadensis distributed across smaller geographical ranges. Fifteen microsatellite loci were used to genotype 172 individuals from 18 unmanaged and naturally occurring collection sites. Our results indicated presence of population structure, overall high genetic diversity (H E = 0.63, H O = 0.34), and moderate genetic differentiation (F ST = 0.14) among the collection sites. Two major genetic clusters within the smaller geographical distribution were revealed by STRUCTURE. Our data suggest that native C. canadensis populations in the fragmented area around the Georgia–Tennessee border were able to maintain high levels of genetic diversity, despite the presence of considerable spatial genetic structure. As habitat isolation may negatively affect gene flow of outcrossing species across time, consequences of habitat fragmentation should be regularly monitored for this and other forest species. This study also has important implications for habitat management efforts and future breeding programs.

Long-Lasting Insecticide Netting for Protecting Tree Stems from Attack by Ambrosia Beetles (Coleoptera: Curculionidae: Scolytinae).

Ambrosia beetles (Coleoptera: Curculionidae: Scolytinae) are destructive wood-boring insects of horticultural trees. We evaluated long-lasting insecticide netting for protecting stems against ambrosia beetles. Container-grown eastern redbud, Cercis canadensis, trees were flood-stressed to induce ambrosia beetle attacks, and deltamethrin-treated netting was wrapped from the base of the stem vertically to the branch junction. Trees were deployed under field conditions in Ohio, Virginia, Tennessee, and Mississippi with the following treatments: (1) flooded tree; (2) flooded tree with untreated netting; (3) flooded tree with treated ‘standard mesh’ netting of 24 holes/cm2; (4) flooded tree with treated ‘fine mesh’ netting of 28 holes/cm2; and/or (5) non-flooded tree. Treated netting reduced attacks compared to untreated netting and/or unprotected trees in Mississippi in 2017, Ohio and Tennessee in 2018, and Virginia in 2017–2018. Inconsistent effects occurred in Mississippi in 2018. Fewer Anisandrus maiche, Xylosandrus germanus, and Xyleborinus saxesenii were dissected from trees deployed in Ohio protected with treated netting compared to untreated netting; trees deployed in other locations were not dissected. These results indicate long-lasting insecticide netting can provide some protection of trees from ambrosia beetle attacks.

Characterization and phylogenetic analysis of the complete chloroplast genome of Cercis canadensis ‘Forest Pansy’

Cercis canadensis ‘Forest Pansy’ is a tree species with high ornamental value, which complete chloroplast (cp) genome was sequenced, assembled, and annotated. The genome size is 158,960 bp with a total GC content of 36.17%. The cp genome is made up of a large single-copy region (88,114 bp), a small single-copy region (19,590 bp), and two inverted repeat regions (25,628 bp each). It contains 128 genes, including 84 protein-coding genes, 36 tRNA genes, and 8 rRNA genes. Eighteen genes were duplicated in IRs. The maximum-likelihood (ML) phylogenetic analysis indicated that the Leguminosae species are grouped together, and C. canadensis ‘Forest Pansy’ is closely related to C. canadensis. The result would provide valuable information for genetic studies on Cercis genus.

Investigations of the sensitivity of ornamental, fruit, and nut plant species to driftable rates of 2,4-D and dicamba

AbstractAn experiment was conducted in 2017 and 2018 to determine the sensitivity of driftable rates of 2,4-D and dicamba with or without glyphosate on common ornamental, fruit, and nut species. Three driftable rates corresponding to ½, 1/20th, and 1/200th of the manufacturer’s labeled rate (1 × rate) of 2,4-D (1.09 kg ae ha−1), 2,4-D plus glyphosate (1.09 kg ae ha−1 plus 1.10 kg ae ha−1), dicamba (0.56 kg ae ha−1), and dicamba plus glyphosate (0.56 kg ae ha−1 plus 1.10 kg ae ha−1) were applied to apple, crabapple, dogwood, American elderberry, American elm, grapevine, hydrangea, red maple, pin oak, peach, pecan, eastern redbud, rose, red raspberry, strawberry, sweetgum, nannyberry viburnum, and black walnut plants. Visible estimates of injury were recorded 28 and 56 days after treatment (DAT). Plant measurements included leaf malformation, tree trunk growth, and shoot length. Across all species, the ½ × rate of 2,4-D plus glyphosate resulted in 61% injury 28 DAT, whereas the ½ × rate of dicamba plus glyphosate resulted in 51% injury. Across plant species and herbicides, ½ ×, 1/20 ×, and 1/200 × rates caused injury ranging from 3% to 100%, 0% to 66%, and 0% to 19%, respectively. Hydrangea was the least sensitive species; grapevine was most sensitive. Changes in plant measurements were dependent on the species and herbicide applied. Treatments at the ½ × or 1/20 × rate resulted in shoot length, leaf malformation, and trunk tree diameter differences for 11, 10, and 7 species, respectively, compared with nontreated plants. Collectively, the measurements and visual injury assessments indicated apple, red maple, peach, and pin oak were more sensitive to treatments containing dicamba, whereas black walnut, grapevine, and American elm were more sensitive to 2,4-D. Although the 1/200 × rates of 2,4-D and dicamba did not result in changes to plant measurements, obvious injury symptoms were observed, which could render these plants unsalable.

Effects of Aggregation Lure and Tree Species on Halyomorpha halys (Hemiptera: Pentatomidae) Seasonal Oviposition.

The brown marmorated stink bug, Halyomorpha halys (Stål), is a polyphagous pest that feeds on a wide variety of agricultural commodities including tree fruits, berries, vegetables, field crops, and ornamental trees and shrubs. Accurate knowledge of where H. halys lays eggs is critical to optimize the potential release of Trissolcus japonicus (Ashmead), a scelionid egg parasitoid native to the same host region as H. halys. Ideally, parasitoids should be released in and around areas with high host density. In southwestern Virginia in 2017 and 2018, we searched trees for egg masses in an urban environment and nonmanaged wooded border environment. We also evaluated the effects of a commercial aggregation lure on the number of eggs being deposited. This aggregation lure, when combined with methyl (E,E,Z)-2,4,6-decatrienoate (MDT), has been shown to attract both adult and nymph H. halys and its effects on egg laying were not known. Results of this study showed no difference between the number of eggs laid on trees with and without lures. Catalpa trees, Catalpa bignonioides Walter, had the most egg masses throughout the course of the study; however, the redbud, Cercis canadensis L., had similar numbers in the late July and August. There was an overall trend with more eggs masses found on trees with fruiting structures present. This information can provide insight on where and when to make augmentative releases of egg parasitoids for H. halys.

Interaction of a Preventative Fungicide Treatment and Root Rot Pathogen on Ambrosia Beetle Attacks during a Simulated Flood Event.

Flooding can increase tree susceptibility to root rot pathogens as well as attacks by ambrosia beetles attracted to stress-induced ethanol emissions. The objective of this study was to investigate the interaction of a preventative fungicide treatment and root infection with Phytophthora cinnamomi on ambrosia beetle attacks in flood stressed trees. A fungicide (Pageant® Intrinsic®) was evaluated in two flood trials using Eastern redbud and tulip poplar trees with treatments including the fungicide with or without pathogen or no fungicide with or without pathogen. Fungicide treated trees had fewer ambrosia beetle attacks, particularly in trees without P. cinnamomi co-infection. In a follow-up experiment, ethanol content was evaluated in flooded redbuds to determine if the fungicide treatment reduced stress-induced compounds. All flood stressed trees began producing ethanol within 24 h post flooding, regardless of fungicide treatment or P. cinnamomi infection. We conclude that pre-treatments of a fungicide can provide protection from ambrosia beetle attacks during an extreme flood event, but that protection is reduced if a root rot pathogen is also present. Additionally, rejection of fungicide treated trees was not related to the absence of ethanol, as the fungicide-treated plants released ethanol in quantities similar to non-treated trees.

The tree vegetation of the Kherson State Agrarian University Arboretum

One of the largest objects of landscaping on the territory of the city of Kherson is the Arboretum of the Kherson State Agrarian University (further the arboretum of KSAU). The harsh natural conditions of southern Ukraine caused the poor species composition of aboriginal tree plants. Therefore, on the arboretum territory the process of introduction, adaptation and naturalization of various types of ornamental plants has been carrying out for 70 years. In 1983, the Arboretum was given the conservation status of a park-monument of landscape architecture of local significance. Throughout the history of its creation, experimental research has been conducted on the introduction decorative species of trees and shrubs into the culture. Therefore, a comprehensive analysis of tree plants at the KSAU Arboretum, as well as the development of proposals for the formation of a range of tree plants for inclusion in the investigated object and for greening the city of Kherson are relevant to date.During the inventory of the species composition of tree plants in the Arboretum of KSAU, 126 species belonging to 87 genera, 44 families, 21 orders, 2 classes and 2 divisions have been identified. The Magnoliophyta division (120 species; 95.2%) prevails in the taxonomic structure of the arboretum dendroflor. The division of Pinophyta is represented by only six species (4.8%). The leading families of the given dendroflora are Rosaceae Juss. (32 species; 25.4% of the total species numnber), Salicaceae Lindl. (10 species; 7.9%), Caprifoliaceae Juss. (6 species; 4.8%), Oleaceae Lindl. (6 species; 4.8%), Ranunculaceae Juss. (5 species; 4.0%). The Families of Cupressaceae Bartl. and Fabaceae Lindl. are presented by four species each (3.2%). Other families are represented by fewer species. There have been discovered 10 life forms of tree and semi-tree plants in the Arboretum. The most numerous is a group of single-stranded deciduous trees (51 species; 40.5%) and erect deciduous shrubs (39 species; 31.0%). Most plants are erect and deciduous.The vast majority of species (111 species; 88.1%) are introduced from different parts of the world (Europe, Asia, and North America). Only 15 species of tree plants are aboriginal ones: Betula borysthenica Klok, Populus nigra L., P. alba L., P. tremula L., Quercus robur L., Corylus avellana L., Ephedra distachya L., Amygdalus nana L. and others. The analysis of the ecological structure showed that the groups of scioheliophytes (49 species; 38.9%) and heliophytes (44 species; 34.9%) predominate among the heliomorphs, xeromesophytes (56 species; 43.8%) are quantitatively predominant in the hygromorphs. Thermomorphs are represented by megathermophytes (68 species; 53.1%) and mesothermophytes (60 species; 46.9%). In relation to the trophy of the substrate, plants that grow on poor substrates – oligotrophy (86 species; 67.2%) dominate. Sozological analysis showed that in the KSAU Arboretum has plants from the Red Book of Ukraine: Betula borysthenica Klokov, the endemic of the Northern Black Sea and Syringa josikaea J.Jacq. ex Rchb., as well as species included in the List of Protected Plants in the Kherson Region: Clematis integrifolia L., Ephedra distachya L. and Quercus robur L. The dominant of formation of Amygdalieta nanae – Amygdalus nana L. grows on the territory of the Arboretum.Taking into account the climatic conditions of the city of Kherson, high solar activity during the summer period, low rainfall, temperature fluctuations during the year and seasons, as well as the microclimatic conditions of the Arboretum location, we propose to expand its range of tree plants in the future by including plants that combine decorative qualities with resistance to the environmental conditions: Magnolia soulangeana Soul.-Bod., Liriodendron tulipiferum L., Cornus alba L., Cotoneaster horizontalis Dcne. and C . multiflorus Bunge, Prunus serrulata Lindl., Cercis canadensis L., Picea pungens f. glauca , Acer ginnala (Maxim.) Maxim. and Acer platanoides L., Cotinus coggygria Scop., as well as to expand the range of glacial plants of Metasequoia glyptostroboides Hu et Cheng, Pseudotsuga menziesii (Mirb.) Franco, decorative forms of the genera Taxus L., Buxus L., Quercus L., Tilia L., Berberis L., Thuja L., Juniperus L., Chamaecyparis Spach and others. Decorative species that will grow successfully on the territory of the Kherson State Agrarian University Arboretum can be planted in other landscaping facilities of Kherson City.

Converting Lawn to Restored Forest on a Midwest College Campus: A Seven Year Assessment of Herbaceous Plant Establishment

Human development has resulted in significant loss of forested areas and associated biodiversity. Preserving and restoring woodland habitats is critical for recovering this biodiversity and the ecosystem services it provides. While forest restoration projects typically focus on improving degraded woodlands, fewer studies have investigated the conversion of suburban, lawn-dominated landscapes back into healthy forest ecosystems. In this study, we evaluated different strategies for establishing a forest ecosystem on land that for over 20 years had been maintained as turf grass. Five native, herbaceous woodland plants (Arisaema triphyllum, Carex pensylvanica, Diarrhena americana, Geranium maculatum , and Podophyllum peltatum ) were planted around five nurse trees (Acer rubrum, Amelanchier arborea, Cercis canadensis, Tsuga canadensis , and Viburnum opulus var. americanum ) in four soil treatments: bare soil; 5 cm of leaf mulch; rototilling and 5 cm of leaf mulch; and 10 cm of leaf mulch. We assessed the prevalence of weeds in each soil treatment two years after planting. We also analyzed survivorship and performance data seven years after planting to evaluate how nurse tree species and soil treatment affect herbaceous species. We found that mulching decreased the prevalence of weedy species and did not affect survivorship or performance of herbaceous transplants. Overall survivorship varied significantly, with P. peltatum having the highest survivorship and C. pensylvanica the lowest. Survivorship was influenced by nurse tree species, and was lowest around T. canadensis . Similar restoration projects should consider using species that were successful in this project, avoid planting near T. canadensis , and consider leaf mulch for weed control.

SSR Markers Reveal the Genetic Diversity of Asian Cercis Taxa at the U.S. National Arboretum

The redbud (Cercis L. species) is a popular landscape plant grown widely in the United States. There are more than 20 cultivars of eastern redbud (Cercis canadensis L.) and at least three cultivars of Asian taxa (primarily Cercis chinensis Bunge) in the trade. The U.S. National Arboretum (USNA) has a diverse collection of Cercis germplasm collected in North America and Asia. Fourteen genomic simple sequence repeat (genomic-SSR) markers were used to analyze the genetic diversity of 53 accessions of Asian Cercis taxa from our collection, including C. chinensis, Cercis chingii Chun, Cercis gigantea ined., Cercis glabra Pamp., Cercis racemosa Oliv., and Cercis yunnanensis Hu and W. C. Cheng. SSR markers detected an average of 5.7 alleles per locus with a range of two to nine alleles. A dendrogram was generated by unweighted pair group method with arithmetic mean (UPGMA) cluster analysis using the Jaccard similarity coefficient. Four major clusters were identified. Accessions tended to group by taxa or provenance, but with some notable exceptions caused either by misidentification or nomenclatural confusion in the species. This information will be used for collection management and for making decisions in the breeding program to maximize genetic diversity of cultivated Cercis.

Anthocyanin Pigments in Redbud (Cercis spp) Flowers

Redbud (Cercis spp.) is used as a spring flowering ornamental tree and is found wild in much of North America. Typically flowers are light purple although there are selected cultigens that are white, rose, or red-purple. Flowers from cultigens common to the eastern U.S. and from wild Eastern redbud (C. canadensis) were collected and tested for color and anthocyanin pigment composition. The anthocyanins cyanidin 3-glucoside, petunidin 3-glucoside, peonidin 3-glucoside, and malvidin 3-glucoside were most aboundant in purple, rose, and red-purple redbud flowers and total anthocyanin content was 2263 to 8730 mg•kg DW-1. Small amounts of delphinidin, cyanidin, and petunidin 3, diglucosides were also present. Most of the typical purple-flowered redbuds contained cyanidin 3-glucoside as the dominant pigment, while the red-purple flowered 'Appalachian Red' and 'Crosswicks Red' contained malvidin 3,5-diglucoside as the dominant anthocyanin. An unknown anthocyanin was present in all redbud flowers, and was higher in the red-purple flowered phenotypes.

Integrating Kaolin Clay for Ambrosia Beetle Management in Ornamental Crops of Eastern Redbud

Invasive ambrosia beetles (Coleoptera: Curculionidae) are an important pest problem at ornamental tree nurseries. Available chemical treatments are not completely effective and, due to the length of the beetle dispersal period and insecticide breakdown, repeated treatments can become costly in terms of application expense and nontarget impacts. Additional options are needed to reduce application frequency and to provide an acceptable level of crop protection. Four treatments were tested using ethanol-injected eastern redbud trees at research sites in Mississippi (MS) and Tennessee (TN) over 2 years (2014–15), with the number of new ambrosia beetle galleries compared over time on 1) nontreated control trees, 2) kaolin-treated trees, 3) bifenthrin-treated trees, and 4) kaolin + bifenthrin (k + b)-treated trees. Kaolin-treated trees rapidly lost their coating after rain events and, at 6 days after treatment (DAT) in TN, no differences were detected in the number of beetle galleries between kaolin and nontreated control trees. Kaolin + bifenthrin-treated trees appeared to retain treatment residue longer, but were not better-protected than bifenthrin-treated trees at any time. Further research is needed to determine whether an adjuvant, such as a surfactant, spreader, or sticker, may enhance the modest impact offered by kaolin in our test, or if a reduction in rates of bifenthrin may be allowable.

Effect of Simulated Anthonomus signatus (Coleoptera: Curculionidae) Injury on Strawberries (Fragaria × ananassa) Grown in Southeastern Plasticulture Production.

Female strawberry bud weevils (Anthonomus signatus Say) oviposit in developing flower buds of strawberries (Fragaria spp.), caneberries (Rubus spp.), and red bud (Cercis canadensis). After laying a single egg, weevils will girdle or "clip" the buds at the pedicel, killing the bud and preventing fruit development. This injury is of concern to commercial strawberry growers, who typically assume the loss of one clipped bud is the loss of one average sized fruit, causing the economic threshold to be set extremely low. There is evidence of compensation in some cultivars of strawberries, but research has previously only been conducted in perennial strawberry production. The majority of strawberries in the southeastern United States are grown in annual plasticulture systems. We assessed the ability of five strawberry cultivars commonly grown in annual plasticulture to compensate for A. signatus injury by removing buds at different growth stages. There was no effect of bud removal on total yield in any of the cultivars tested. Harvest timing was affected by simulated A. signatus damage in some cultivars, which may be an important consideration for direct market strawberry growers.

Patterns of tree mortality in a temperate deciduous forest derived from a large forest dynamics plot

AbstractTree mortality is one of the most influential drivers of forest dynamics, and characterizing patterns of tree mortality is critical to understanding forest dynamics and ecosystem function in the present era of global change. Here, we use a unique data set of mortality in a temperate deciduous forest to characterize rates and drivers of mortality. At the 25.6‐ha Center for Tropical Forest Science—Forest Global Earth Observatory forest dynamics plot at the Smithsonian Conservation Biology Institute (Virginia, USA), we conducted two full tree censuses in 2008 and 2013 and then tracked mortality over the next 2 years (2014 and 2015). Overall, the mortality rate, m, of stems ≥10 cm diameter was 1.3–2.1%/yr. Biomass mortality, M, was 1.9–3.4 Mg·ha−1·yr−1 at the stand level (0.6–1.1%/yr of biomass), less than biomass gains from growth and recruitment, resulting in net live biomass accumulation. Small stems died at the highest rate; however, contributions to M increased toward larger size classes. Most species had m < 2%/yr and M < 0.25 Mg·ha−1·yr−1 (<3%/yr of biomass), whereas two to four species had anomalously high mortality rates during each census period, accounting for 15–24% of m (n = 2, Cercis canadensis, Ulmus species) and 39–75% of M (n = 4 Quercus species). Stems that died, whether or not in association with mechanical damage, tended to grow more slowly in preceding years than surviving stems and, for certain shade‐intolerant species, tended to be in neighborhoods with higher basal area. These findings show how relatively fine‐scale mortality processes contribute to stand‐level compositional change and carbon cycling. The mortality patterns reported here will provide a valuable basis for understanding future disturbance events within eastern deciduous forests and for comparing across forest types.

Cloud forests on rock outcrop and volcanic soil differ in indicator tree species in Veracruz, Mexico

The tropical montane cloud forest (TMCF) of central Veracruz, Mexico, predominantly grows on volcanic substrate from the Quaternary (2–0.08Mya), but in very small areas it grows on shallow soils over limestone rock outcrops from the Cretaceous (90Mya). Our objective was to contrast the vegetation structure and tree species composition of forest communities growing on rock outcrops (FOR) with nearby forests on prevalent volcanic soil (FOV). Results show that species richness and vegetation structure were similar between FOR and FOV. However, a clear difference was revealed by indicator species analysis (ISA), and multinomial classification model (CLAM). ISA and CLAM, respectively, identified 14 indicators and 13 specialists in FOR, whereas, they identified 7 indicators and 14 specialists in FOV. Some FOR indicators were Cercis canadensis, Clusia guatemalensis, Garrya laurifolia, Ostrya virginiana and Quercus pinnativenulosa. Some FOV indicators were Carpinus tropicalis, Clethra macrophylla, Liquidambar styraciflua and Quercus xalapensis; these species are also common in several Mexican TMCF. Our study demonstrates that the tree community on rock outcrops differs from the surrounding forest on volcanic soils; this is of particular interest because of its different species assemblage and contribution to the high beta diversity of the region.

Flood Stress as a Technique to Assess Preventive Insecticide and Fungicide Treatments for Protecting Trees against Ambrosia Beetles.

Ambrosia beetles tunnel into the heartwood of trees where they cultivate and feed upon a symbiotic fungus. We assessed the effectiveness of flood stress for making Cercis canadensis L. and Cornus florida L. trees attractive to attack as part of insecticide and fungicide efficacy trials conducted in Ohio and Virginia. Since female ambrosia beetles will not begin ovipositing until their symbiotic fungus is established within the host, we also assessed pre-treatment of trees with permethrin, azoxystrobin, and potassium phosphite on fungal establishment and beetle colonization success. Permethrin reduced attacks on flooded trees, yet no attacks occurred on any of the non-flooded trees. Fewer galleries created within flooded trees pre-treated with permethrin, azoxystrobin, and potassium phosphite contained the purported symbiotic fungus; foundress’ eggs were only detected in flooded but untreated trees. While pre-treatment with permethrin, azoxystrobin, and potassium phosphite can disrupt colonization success, maintaining tree health continues to be the most effective and sustainable management strategy.

Inheritance and allelism of morphological traits in eastern redbud (Cercis canadensis L.).

Inheritance of purple, gold, and variegated foliage types, weeping architecture, and double flower was explored in F1, F2, and backcross families resulting from controlled hybridization of eastern redbud (Cercis canadensis L.). Potential allelic relationships were explored when possible. Inheritance analysis in families derived from controlled hybridization of ‘Covey’ (green leaf) and ‘Forest Pansy’ (purple leaf) suggest that purple leaf color and weeping architecture are both controlled by single recessive genes, for which the symbols pl1 and wp1 are proposed, respectively. Inheritance of gold leaf was explored in families of ‘Covey’ (green leaf) × ‘Hearts of Gold’ (gold leaf). Interpretation of inheritance of gold leaf in these families was confounded by the recovery of a leaf color phenotype in the F2 family unlike either parent. However, data suggested the action of a single locus controlling gold leaf color in ‘Hearts of Gold’, and that instability of gold leaf expression may be based on transposable element activity. Segregation of gold leaf in the F2 families of ‘Texas White’ [green leaf (C. canadensis var. texensis)] × ‘JN2’ [gold leaf (The Rising Sun)] did not fit a Mendelian ratio. Analysis of progeny of ‘Silver Cloud’ and ‘Floating Clouds’ (both showing white/green leaf variegation) with non-variegated cultivars demonstrated that variegation in ‘Silver Cloud’ is controlled by a single recessive nuclear gene, while variegation in ‘Floating Clouds’ is controlled by cytoplasmic factors. The symbol var1 is proposed for the gene controlling variegation in ‘Silver Cloud’. Double flower in progeny derived from ‘Flame’ (double flower) suggested that double flower is dominant to single flower, and that ‘Flame’ is heterozygous at the double-flower locus, for which the symbol Df1 is proposed. Allelism studies showed that the gene controlling purple leaf in ‘Forest Pansy’ is allelic to the purple leaf gene in ‘Greswan’ and that the gene controlling weeping phenotype in ‘Traveller’ (C. canadensis var. texensis) is non-allelic to the weeping gene found in ‘Covey’. Allelism of the gold leaf trait in ‘Hearts of Gold’ and ‘JN2’ was investigated, but no clear conclusions regarding allelism could be made due to recovery of leaf color phenotypes unlike either parent.

First record of the psyllid Cacopsylla pulchella (Löw, 1877) (Hemiptera, Psyllidae) from Krasnodar Territory

The invasive psyllid Cacopsylla pulchella (Low) is recorded for the first time from Krasnodar Territory, southern Russia. Cercis canadensis is recorded as a new host for C. pulchella. Feeding of Harmonia axyridis (Pall.) (Coccinellidae) on the nymphs of C. pulchella is reported.

Advancement of tree species across ecotonal borders into non-forested ecosystems

Woody species are increasing in density, causing transition to more densely wooded vegetation states, and encroaching across ecotonal borders into non-forested ecosystems. We examined USDA Forest Service Forest Inventory and Analysis data to identify tree species that have expanded longitudinally in range, particularly into the central United States. We analyzed compositional differences within ecological regions (i.e., subsections) in eastern and western ranges of species using repeated measures ANOVA. We considered differences in outer ranges to indicate range expansion or contraction. We also estimated the shift in forest area and basal area relative to the center of the US and compared change in deciduous forest land cover. Out of 80 candidate species, 22 species expanded to the west, seven species expanded to the east, and five species expanded in both directions. During the survey interval, eastern tree species advanced into the predominantly non-forested ecosystems of central United States. Eastern cottonwood, eastern hophornbeam, eastern redbud, honeylocust, Osage–orange, pecan, red mulberry, and Shumard oak represent some of the species that are advancing eastern forest boundaries across forest-grassland ecotones into the central United States. Forest land has shifted towards the center of the continent, as has the center of mean tree basal area, and a simple comparison of deciduous cover change also displayed forest advancement into the central United States from eastern forests. The expanding species may spread along riparian migration corridors that provide protection from drought. Humans use the advancing tree species for windbreaks, fencerows, and ornamental landscaping, while wildlife spread fruit seeds, which results in unintentional assisted migration, or translocation, to drier sites across the region.

Evaluation of Polymerase Chain Reaction (PCR)-Based Methods for Rapid, Accurate Detection and Monitoring of Verticillium dahliae in Woody Hosts by Real-Time PCR.

Verticillium wilt, caused by Verticillium dahliae, is one of the most economically important diseases of woody hosts such as ash (Fraxinus spp.), sugar maple (Acer saccharum), and redbud (Cercis canadensis). The causal agent has a broad host range, including not only woody hosts but also important vegetable and field crops, and it is distributed worldwide. Diagnosis of V. dahliae in infected woody hosts is often based on the occurrence of vascular discoloration and time-consuming isolation. However, not all woody hosts exhibit vascular discoloration, and not all vascular discoloration symptoms are due to infection by V. dahliae. In this study, real-time polymerase chain reaction (PCR)-based assays were evaluated and employed for rapid and accurate detection of V. dahliae in different woody hosts. High-quality DNA was extracted in large quantities from presumptively infected woody hosts by collecting drill-press shavings from sample tissue, bead beating, and extracting using a cetyltrimethylammonium bromide method. Six published primer sets were evaluated against genomic DNA of V. dahliae as well as selected negative controls, and two sets (VertBt-F/VertBt-R and VDS1/VDS2) showed promise for further evaluation using DNA extracts from field samples. The VertBt primers amplified a species-specific 115-bp fragment of the expected size, while the VDS primers amplified the expected specific 540-bp fragment. However, the VertBt primer set exhibited higher sensitivity in detection of V. dahliae even in asymptomatic trees. The PCR-based methods developed here could be used as rapid tools for pathogen detection and monitoring, thus informing plant pathogen management decisions.

Allelopathic potential of invasive species is determined by plant and soil community context

The search for mechanisms to explain the competitive dominance of invasive species has generated much interest in testing for allelopathy as a major mechanism of plant invasion. The Novel Weapons Hypothesis postulates that invasive plants disproportionally impact native plants by producing novel allelochemicals. We studied the allelopathic potential of three invasive and three native species on twelve co-occurring plant species in the Eastern Deciduous Forest of Indiana, USA, using foliar leachate and soil with an intact microbial community. Our bioassay was a full factorial test of two soil treatments and six foliar leachates on the germination and growth of 12 species (2 × 6 × 12 full factorial). The strength of allelopathic impacts were context dependent, with significant 3-way and 2-way interactions between leachate species, target species, and soil microbial communities (live vs. sterilized). Allelopathic potential was different between life stages of the target species. Ligustrum vulgare’s and Lonicera maackii’s impacts on some native species supported the Novel Weapons Hypothesis; however, the invasives as a group did not significantly affect growth and had a weaker effect on germination than the effect of certain invasive species individually. For example, native Cercis canadensis reduced germination and growth in some conditions. Our results in the live soil treatment indicate that some natives, such as Elymus hystrix, should be resistant to Lonicera maackii and Ligustrum vulgare, but these shrubs’ allelopathy could contribute to the decline of susceptible native species.